For our fourth episode, we decided to try making a long, in-depth show about those squiggly word puzzles you find all over the internet, called CAPTCHAs. This is our first show that contains interviews, including of the happy fellow you see above, Dr. Andrei Broder, the Chief Scientist at Yahoo!. You’ll hear from him quite a bit in this episode.
This show is almost 50 minutes long. We hope you enjoy it. Right now we’re thinking about this as sort of a special occasion. Most of our shows will likely be shorter — mostly because they’re easier to make (Nat spent over 100 hours on this one). Unless you tell us long is the way to go!
And on that note, we’d love to get your feedback on this show in the comments below. Constructive criticism and gushing encouragement are all welcome!
If you want to learn more about the topics we discussed, here are some handy links.
The Interviewees
- Dr. Andrei Broder, Chief Scientist at Yahoo’s Advertising Technology Group
- Ben Maurer, co-founder of reCAPTCHA
- Dr. Kumar Chellapilla, Scientist at Microsoft Research
- Shaun Friedle, creator of the Megaupload autofill CAPTCHA greasemonkey script
CAPTCHA basics
- The official CAPTCHA website
- Alan Turing’s 1950 paper, Computer Machinery and Intelligence, wherein he poses the Turing Test
- A nice little summary of the history of CAPTCHA
- A long Wired article about CAPTCHA and Luis von Ahn’s GWAP project
- reCAPTCHA - solve spam, read books
- CyberLover – the bot that steals personal information
- The Photoshop Phriday competition to make funny pictures from reCAPTCHA word combinations
- A funny xkcd about CAPTCHA and turing tests
- The CAPTCHA patent
- Taylor Hayward’s work on 3D images as CAPTCHAs
Algorithmic attacks on CAPTCHA
- Kumar Chellapilla’s paper on breaking CAPTCHAs at Microsoft Research
- Shaun Friedle’s megaupload autofill CAPTCHA greasemonkey script as broken down in John Resig’s blog
Convolutional Neural Networks
- Video of the Hubel/Wiesel cat brain experiments. Amazing example of reverse engineering.
- Yann LeCun’s LeNet-5, a convolutional neural network. LeCun is one of the originators of the technique.
- A great paper introducing convolutional neural networks
- Convolutional Neural Networks best practices, a Microsoft Research paper from Patrice Simard
CAPTCHA bypass services (aka CAPTCHA farms)
- Inside India’s CAPTCHA solving economy, a ZDNet article
- Decaptcher
- Spyder CAPTCHA assist for myspace
This episode contains two songs from Eternal Jazz Project, a Swedish jazz band that released some of their music under the Creative Commons BY-NC-SA license on magnatune. This episode is distributed under the same license.
Transcript
00:00:00
Broder: There was a procedure called add URL, where you would come to a search engine and you would say, you know, here is the pages I just made. But anyway we had this problem and, of course, there was spammers and there were people that were adding the same page millions of times and wrote little scripts to add their pages. So we had somehow to slow the spammers. And this is how we came up with the idea that we need a test to distinguish between spammers and humans.
00:00:46
Nat: That was Dr. Andrei Broder, the Chief Scientist at Yahoo!, discussing his time at Altavista in 1997, when he led the team that invented a little thing called CAPTCHA.
Alex: And CAPTCHAs are the subject of our program today. We’re going to be exploring the state of the art in CAPTCHA generation and circumvention
Nat: I’m Nat Friedman, reporting from the Bavarian capital of Munich.
Alex: And I’m Alex Graveley, reporting from sunny, cloudy, cold San Francisco.
Nat: And this is Hacker Medley, the podcast for curious hackers.
00:01:28
Nat: Let’s see here. Word verification. Type the characters you see in the picture below. Okay. C-O, I think that’s a U.
Alex: Wait, is this supposed to be a word or is this just letters?
Nat: I think it says [coralia]. Is that a word?
Alex: I don’t know.
Nat: I think it’s just sort of just random letters that are pronounceable. Okay. I think it’s C-O-U, and I think there’s an R like tucked in there and that’s, wait that might not be an A actually. I think that, yeah, that’s an A. And then this is either a B or an LE.
00:02:02
Alex: And here Nat is trying to solve a CAPTCHA, one of those squiggly word puzzles that you see all over the internet, where you have to type in the words that you see in order to enter a blog, comment or create a new mail account or even participate in an online poll.
Nat: The estimates are that we are, human beings as a species, are solving over 200 million CAPTCHAs every single day, but the very first CAPTCHA was implemented at AltaVista back in 1997. I interviewed Dr. Broder at his office in Santa Clara and asked him to tell us how it happened.
Broder: I think from the very beginning we had kind of an idea that the problem has to be some kind of a pattern recognition problem because this is one area where humans are much better than machines. And at some point it sort of started from, I think some lunch discussion and we were pointing out, someone was pointing out machines are not yet incredibly good at playing chess. How come humans cannot make so much computation are good at chess and it’s all about pattern recognition. So we knew that we need a pattern recognition problem. And then we came with this one.
00:03:07
Nat: How did you come up with the algorithm for distorting text?
Broder: That one is a lot easier to tell you how we decided what things are because actually I had a scanner at home, and scanners were not so cheap as today, and I had a scanner, and I believe was made by Brothers but I’m not 100% sure, and the scanner came with a manual and they also had some OCR software, which came with the scanner. And pretty much I looked in the manual and everything in the manual that they said it’s bad for OCR.
Andrei: We decided why don’t we make it. So one of the things that we’re saying, well it’s bad if the letters are misaligned, so we said okay they should be misaligned. And it’s bad if you use multiple fonts, so we said okay use multiple fonts. So it was all there.
00:04:07
Nat: That’s a pretty interesting story, huh?
Alex: Yeah, I love those old stories of like hacker epiphanies that solve really complex problems. The funny thing is that search engines today don’t even use this scheme anymore, they just use PageRank, which crawls the whole web. But instead, CAPTCHAs have turned out to be incredibly valuable for locking out spammers from pretty much all aspects of the internet.
Nat: You know, what’s kind of amazing to me is that these guys, this little team at AltaVista 12 years ago, they came up with this human detection technique and it’s pretty much exactly what we’re using today.
Alex: Yeah, I mean it looks pretty much the same to us but it is somewhat different, like the state-of-the-art has pushed these things towards being much harder for computers to solve.
00:04:54
Nat: Yeah, that’s true. I mean pattern recognition techniques and AI and computer vision have advanced a lot since then. And actually, that’s a good point, that kind of brings us to why Alex and I think CAPTCHAs are so interesting. That little image, that little rectangle of distorted text on your web browser, that is kind of like a window into the world of artificial intelligence and how it relates to human capabilities.
Alex: Yeah, and specifically it’s just like this really interesting set of problems which are sort of described in that they’re tests that computers can generate and grade the answer to but which they can’t themselves solve very easily but that humans can solve really quickly.
Nat: So here are the criteria. In order to be a viable CAPTCHA, a test has to be something that’s beyond the frontier of current artificial intelligence, but well within the capabilities of even really, really average people. So in a certain way, the set of all viable CAPTCHAs describes the ways in which people are still better and more capable than computers.
00:05:53
Alex: Yeah, and it shows you sort of the places where AI still has to grow and the limitations of what we can do, at least with regards to image recognition.
Nat: That’s a good point. But, of course, bad news is that AI is getting smarter and we’re not. So, you know, for the time being, at least when it comes to recognizing distorted text, we’re still well beyond computers but there’s no reason it’s going to stay that way stay forever.
Nat: Actually, Alex, by the way, the idea of CAPTCHA goes back to an earlier concept called a Turing Test.
Alex: I’ve heard of Turing Tests but it’s funny, I didn’t know that CAPTCHA stood for a Completely Automated Public Turing Test to tell Computers and Humans Apart, which is a pretty long acronym, but the important thing in there is that it is a form of Turing Tests. Nat maybe you can explain what that is?
Nat: Sure. So back in 1950 Alan Turing, the father of computing, wrote this really amazing paper called Computer Machinery and Intelligence. And what you have to understand is, in 1950 the transistor was only 3 years old. So computers were like really big, they were room sized, they were really loud and they didnít do very much. So it was in this world of fairly limited computer capabilities that Turing asked an enormous question, and the question was: “Can machines think?” And this is like a philosophical question, and in order to answer it you’d have to define what thinking is.
00:07:13
Alex: But I mean it’s interesting because people are just sort of sitting around with this big old computers waiting for punch cards to be processed and they had their heads in the clouds of these sort of abstract questions.
Nat: Right. Now instead of going in a total abstract route though, Turing devised, he invented a game, a very concrete game, which he called “The Imitation Game.” And the way people usually describe the game is, you have a person who’s a judge, and he’s communicating with someone else who’s in another room, who could be a computer or a human being and they’re talking through little text messages, like IM or something, and the question is: can the judge tell if he’s talking to a computer or a person?
00:07:50
Alex: That’s sort of what’s become the Turing test, which has been around so long at this point that it actually represents sort of this like unachievable holy grail of artificial intelligence. And it represents, if it ever gets solved it represents the point at which computers can really convincingly simulate the interactions between humans.
Nat: Yeah. Actually when I was a little kid my friends and I used to talk about the Turing Test, as you said like a kind of major milestone in artificial intelligence that we figured would have been solved by now. But I hadn’t actually read the paper until we started doing the research for the show and what I discovered is that what Turing actually wrote is different from what we just described. See in Turing’s original paper there’s three people, there’s a man, and a woman, and the judge, and they’re all in separate rooms, and the judge is trying to guess which is the man and which is the woman. And then what you do is you take either the man or the woman and you replace them with a computer, and the question is, does that change the judge’s accuracy from when he was talking with two humans?
00:08:51
Alex: Kind of a weird twist. And the computer actor in that specific scenario is like trying to trick the judge into thinking that the human is lying and it’s all very confusing. I still don’t fully understand why that question is posed in such an obscure and specific way but, you know, it’s Turing so chances are good that he was thinking about something that I’m not.
Nat: No question about that.
Alex: You know, it’s interesting because I think the Turing test is only hard to pass if you suspect you’re talking to a computer.
Nat: Yeah. Actually there’s a whole bunch of examples of people spending hours talking to even like really poorly implemented chat bots that don’t even put a delay in before they respond to someone’s IM or something like that. So they respond in a tenth of a second. And actually I found a really funny screenshot online, it turns out there’s a Russian chat bot that’s called cyber lover, and what it does is it goes into chat rooms and on IM and it poses as an attractive female and it enters IM conversations with men, and it kind of gradually convinces them through these faked human interactions to give up their personal information. And so the screenshot is of the dashboard for this chat bot and you can see all the men that it’s talking to and it reports as it gets their full name and their address and their credit card numbers and that sort of thing. We’ll have to put that up on the website.
00:10:21
Alex: I’m just going to go call Visa real quickly.
Nat: Getting back to the Turing test, though, there’s a bet on the site longbets.org, one of my favorite websites, between Mitch Kapor, who’s the founder of Lotus, and Ray Kurzweil, as to whether a computer will be able to pass a Turing test by 2029.
Alex: Yeah, and that’s the commonly understood concept of the Turing test, not the sort of gender guessing, gender faking one. Mitch Kapor is betting that computers won’t do it, which seems kind of negative to me, and Ray Kurzweil is betting that they will because his sort of whole singularity concept depends on it. And it’s a real bet. There’s $20,000 on the line.
00:11:04
Nat: So Alex, Turing posed this big question back in 1950, and then for 46 years, the AI community worked like crazy to try to build algorithms that could imitate human capabilities and even really simple uncontrolled situations. And they haven’t really quite got there. Actually I have a little blast from the past for you, Alex. Let’s listen to this.
DR SBAITSO CLIP
Alex: Oh man, It’s my very first shrink.
Nat: I don’t know if you remember that from the sound blaster?
Alex: I totally do. It’s like one of those programs that were on the, it was one of the demos that came on the sound blaster install disc.
Nat: Yeah. And then they had one with the talking parrot. You remember that, too? It had a different voice?
Alex: I kind of remember the talking parrot. Can you simulate the voice for me?
00:11:52
Nat: I don’t think I could. So because computers were having so much trouble at even really simple human tasks, let alone actually imitating people in a human context, the conventional wisdom about AI has been, for decades, that AI is in a rut. But then in 1996, a researcher at the Weizmann Institute in Israel named Moni Naor, he looked at the situation and he saw an opportunity. He figured that the things that people could do that AI was still failing to do, he figured could be used by COMPUTERS to automatically tell computers and humans apart.
Alex: Moni’s paper is called “Verification of a human in the loop or Identification via the Turing Test.” And he had a bunch of really cool ideas, some kind of novel concepts for the kinds of puzzles that you could pose to humans to determine if they were in fact human.
Nat: Most of those puzzles you’ll see are kind of in the areas of like sensory processing, image recognition, that kind of thing. Actually I think we should just read a couple.
Alex: Alright, yeah. There’s one that was the Gender recognition, which is actually kind of difficult if you show a picture of a face determining whether or not it’s a male or a female.
00:12:56
Nat: I have trouble with that just in real life.
Alex: Me, too. I got hit the other day because of it. And there’s facial expression understanding, whether the person in the picture is happy or sad. And then there’s identifying body parts, which actually seems like a really difficult problem to me for computers to solve, being able to tell which, in a random picture, whether or not you can highlight the arm or the leg.
Nat: Hereís one I like, filling in words. Given a sentence where the subject has been deleted and a list of words, select one for the subject.
Alex: That’s kind of cool. Sort of text comprehension.
Nat: And he also here mentions handwriting understanding, which is actually pretty close to what CAPTCHAs ended up being.
Alex: And he mentions also speech recognition, which is used in audio CAPTCHAs today for blind people.
Nat: So I mean Moni’s paper gives us a pretty good inkling of what CAPTCHA could be, but he wrote the paper before CAPTCHA was actually invented. And a lot of these particular ideas, well they didn’t turn out to be that great.
00:13:54
Alex: Yeah, things like drawing a circle around a person in a scene or a person’s body part is actually kind of annoying to do in practice. And also things like guess the word that fits into the sentence you can do by, if you index a lot of web pages you can determine which sentences are common or which word structures are very common.
Nat: And actually whenever you have a test that doesn’t have very many choices, like for example a binary choice, like male or female, if you just write a script that guesses randomly you’re going to be right 50% of the time. So that’s a pretty good pass rate for a pretty short script. So you have to give the user like lots of binary choices, like five or ten or something like that, to make the random guessing pass rate low enough or whatever. But anyway, totally independently of this paper that Moni Naor’s wrote, you had the work that was going on at Altavista. So kind of industry and academia were converging on the same point.
00:14:48
Alex: Right. And a few years later at CMU, this totally awesome guy named Luis von Ahn and his professor Manuel Blum wrote a paper where they coined the term CAPTCHA and sort of formalized the whole concept. One thing that’s totally awesome in this paper and one of the reasons I like CAPTCHAs so much is that it points out that CAPTCHAs are pretty much a win-win situation, “either the CAPTCHA is not broken and there is a way to differentiate humans from computers, or the CAPTCHA is broken and a useful AI problem has been solved.”
Nat: Yeah, I love that, too. I think that’s really cool. So since 1996, 1997, the time when AltaVista invented CAPTCHA and thee papers, CAPTCHAs have become super wide spread. Millions are soles every day. And, by the way, the average CAPTCHA takes about 14 seconds to solve. So if you multiply that out that’s a lot of time that’s being spent by people solving CAPTCHAs every day. And with all this work being done, Luis von Ahn saw an opportunity, and with a couple of other people, founded a company called reCAPTCHA.
00:15:48
Ben Maurer: So my name is Ben Maurer. I’m one of the cofounders of reCAPTCHA and I’m responsible for the design of our API and for our infrastructure.
Ben: So people are solving 200 million CAPTCHAs a day, let’s say, and what they’re doing is they’re spending time doing something that by definition a computer can’t do. That’s automatically valuable because if we could give people a task that is useful then we’re getting something that we don’t otherwise have the ability to get. And so we said what can we do with all this, you know, with all this human computation power?
Alex: So just to cut in, in case you don’t know what reCAPTCHA is, you’ve probably seen these before: they’re the CAPTCHAs that have two words that you have to type, the words are usually in some kind of old or smudgy print face, and there’s maybe a line drawn through them.
Ben: And what we came up with is instead of having one word in the CAPTCHA we have two words and one of them is sort of a fake. It’s not part of the CAPTCHA it’s just a word that we don’t know what it is and we want you to tell us what it is and we do that to digitize books and newspapers and other content that computers can’t read.
00:17:00
Nat: So then what they do is they run two different OCRs over the text. Ben told me that they use a couple of commercial OCRs, and an open source one called Tesseract, which comes from Google, which is now considered pretty state of the art. And they identify words that the OCR software couldn’t recognize or doesn’t have a lot of confidence about. Ben explained it pretty well.
Ben: So OCRs are never 100% sure whether they’re right or not. But what we do is we take multiple OCR engines that use different algorithms and they tend to have failures that aren’t 100% correlated with each other. If they both agree then we sort of say we’re, it’s very likely that the word is correct. We use a few other signals such as, you know, does the word fit in this sentence? Like if you have, you know, one sentence we had in an old newspaper was that the motors ears were running down the street. And motor ears is something that just doesn’t occur in the English language and what happened is a C looked like an E to the OCR and we have the ability to say motor ears is a bigram that just doesn’t typically appear and it’s suspicious.
00:18:07
Nat: By the way, Alex, I thought it was nifty that they also use bigram probabilities to help identify which words the OCRs failed to recognize.
Alex: Yeah, I suspect that they’re using the one provided by Google where they have this huge bigram index, this big database you can download for a small fee, and it basically shows the occurrence of combination of words all over the web.
Nat: It makes sense actually also because Google ended up buying reCAPTCHA pretty recently.
Alex: Yeah. And reCAPTCHA has APIs in a whole bunch of languages. So it’s sort of a general-purpose CAPTCHA platform that you can just embed into your site. And these things are used everywhere, on Facebook, TicketMaster, Craigslist, wikipedia…everywhere..
Nat: Ben told, Alex, that reCAPTCHAs actually getting a whole lot of old books and newspapers transcribed.
00:18:55
Ben: We’ve done about, I think about 50 years worth of the New York Times already and currently reCAPTCHA users are solving 50 million CAPTCHAs a day
Nat: And by the way, Alex, The Times is paying reCAPTCHA for all that digitization work that they’re doing.
Alex: That’s pretty awesomely shrewd right there!
Nat: Definitely.
Alex: And they’re doing all this in pretty standard stuff with Python, nginx, and of a lot of intelligent hackery.
Nat: Actually with all that scale, solving 50 million CAPTCHAs a day, I asked Ben a little bit about the architecture, and specifically how do they store the CAPTCHAs on disk. Is it just on file per CAPTCHA image? And here’s what he saidÖ
Ben: Yeah, that was originally how things worked and that’s a pretty big disaster just because every time you serve a CAPTCHA then you end up doing a disk seek. And when you have a server that can serve a few thousand requests per second you can’t do a few thousand disk seeks per second. It’s just too slow.
Ben: And we found that one file per CAPTCHA, when we would get substantial load on the server the latency would become very high. So we actually use a custom file format to store the CAPTCHAs that allows us to load a bunch of CAPTCHAs into memory at once.
00:20:16
Alex: That’s great. That’s another one of those sort of problems that you only run into when you have really large amounts of scale.
Nat: Yeah, and it’s cool to peek under the covers of an operation like that..
Nat: Now, by the way, reCAPTCHA does just take the scanned word off the page and present it to you unmodified, they actually distort the word a little bit before you see it in the CAPTCHA.
Alex: Right, like I said, they maybe draw a line draw a line through it or they make it wavy. And recently they started using these like XOR blobs where they would sort of switch the foreground of the word with the background of the word for part of the word.
00:20:50
Nat: And the reason, Ben told me, that they do this is because, even though OCR software couldn’t recognize the word, you know, OCR software is not really designed to solve CAPTCHAs, it’s trying to get a balanced view of the document, so it might be possible to build an algorithm that could get enough CAPTCHAs right to be annoying. For example, Ben said that if you took a standard OCR software software and just tweaked it’s algorithm to use its second best guess for what the word could be instead of its best guess that might solve enough reCAPTCHAs to be a problem. So that’s why they add extra distortion just for extra safety.
Alex: Yeah, and everyone we’ve talked to has basically said the same thing, which is that reCAPTCHA is one of the toughest CAPTCHAs out there, which is important because you only need, say, 10% of CAPTCHAs solved by your bot to create thousands of fake Gmail accounts or get a lot of SPAM comments through. So the team at reCAPTCHA works really hard to make their CAPTCHAs as difficult to break as possible, while still trying to keep them easy for humans to solve.
Nat: And they’ve had a pretty good balance but CAPTCHA was not always as secure as it is now. And, Alex, there’s a funny story about that.
00:22:04
Nat: So back in the fall of 2004, Microsoft’s hotmail team, like most webmail services, one of their big concerns was SPAM, and specifically SPAMMERS using hotmail to send SPAM.
Alex: Yeah, and Nat, like every other webmail service on the planet, with the sort of first line of defense is to ask people that are creating a new account to solve a CAPTCHA.
Nat: So hotmail was depending on CAPTCHAs to protect them from SPAM. And they wanted to know: how safe are these things anyway? You know, hard would it really be to build an algorithm to break a CAPTCHA? So being Microsoft, of course, they have a really substantial research division right on campus. So they called up Microsoft Research and got in touch with a scientist in the division there named Kumar Chellapilla, who is a machine learning expert.
00:22:52
Kumar: Yeah, so my actual relationship with CAPTCHA comes from machine learning. So my actual PhD research work was on computational intelligence, and this is trying to build intelligent adversaries or agents that could act and train against humans.
Kumar: So these are models that you could train by giving it like input and output signal. And for some, for my PhD work I did mostly game playing like checkers and chess and so on.
Nat: When Kumar joined Microsoft Research, he did some work on OCR technology and handwriting recognition specifically for their tablet PC project.
Kumar: One of the common areas is signature analysis. How do you get a computer to look at two signatures and tell it to accept the signature or not? These are very, very hard problems.
Nat: And so Kumar sat down and he looked at the most prominent CAPTCHAs on the web from the biggest companies on the web at the time, and here’s what he found.
Kumar: And I was surprised. I have somewhat of an undergrad understanding of image processing, a doctorate level understanding in machine learning, and as I started applying some of these techniques, it was very easy to undo the challenges that were being put forth by the CAPTCHA. And I was so surprised at how quickly this happened, that we immediately, I think in November 2004, December 2004 there this famous machine learning conference called neural information processing systems then that was the first place where we presented a poster.
00:24:17
Kumar: And it was amazing. We had about half a dozen different CAPTCHAs that were provided by several different people in the industry and we could show that many of them you could break like one out of two, one out of four, two out of three.
Nat: Now, Alex, as it turns out, solving a CAPTCHA is something that actually breaks down into two separate problems: first is the problem of segmentation, and then comes the problem of recognition.
Alex: And I didn’t know this beforehand but segmentation is the process of breaking a picture of a word up into individual letters. And the recognition is then taking each one of those sort of subpictures and identifying which letter it represents.
Nat: And what Kumar quickly discovered was that recognizing the letters in most of the CAPTCHAs at the time was pretty easy.
[00:025:01]
Kumar: one of the problems we already solved by the time I started looking at CAPTCHAs was if you give me a single character, moderately distorted but not devastatingly distorted, then you sort of use your mouse or you point to the center of the character, I have techniques that can learn from that signal and basically give you the character that is there at that point.
Nat: The tool that Kumar was using was a special kind of neural network called a convolutional neural network.
Actually, why don’t we start off and tell people what neural networks are.
Alex: Yeah, sure. Neural networks are this sort of pretty widely-used technique in AI that’s been around for a really long time. And the basic idea is that you have these neuron-like elements that have inputs and outputs and the inputs and outputs are sort of arranged with inputs going into other neurons and outputs going into other neurons. So for a given neuron each input has its own weight, which multiplies the input value. The neuron adds up those weighted inputs, and if it’s greater than a certain threshold then the neuron fires, meaning that it sends a signal to its output. And the output signals of all these neurons sort of propagate through the network until you get the “answer” on a specific set of output neurons.
00:26:15
Nat: Exactly. So the basic idea for convolutional neural networks came from an experiment that was done back in 1959 by these two guys, David Hubel and Torsten Wiesel. What they did was they took a cat, and they put it under anesthesia. And then they inserted some electrodes directly into the cat’s visual cortex. And they opened its eyes and flashed different patterns of light and dark lines in front of the cat. And what they found was really interesting, they found that some neurons in the cats visual cortex fired rapidly in response to lines at one angle, and some neurons fired rapidly in response to lines at a different angle. So there was some angle sensitivity to different groups of neurons. And there were other neurons in the visual cortex that were totally angle-independent.
00:26:57
Nat: So what happened subsequent to that is, you know, this was obviously a pretty big result in neurology but some computer scientists got a hold of it and what they realized is they could take neural nets and they could arrange them like a cats visual cortex was arranged. So the lowest level you’d have neurons which are recognizing simple features in the image, like corners, edges at a certain angle or end points in certain regions of the image. And then there would be subsequent layers, which are usually called the hidden layers, in the neural network, and these subsequent layers would sort of combine those basic features to detect higher-order characteristics or features in the image. And if you have enough of those and the right kind you can start to recognize even really distorted letters or objects or things like that. So it turns out that this special type of network, this convolutional neural network, which is sort of roughly based on the way vision works in mammals, is really good at image recognition.
00:27:53
Nat: Specifically, these networks were really good at recognizing handwriting. And so when Kumar got assigned the whole CAPTCHA project he’d already been through Tablet PC and he had all this handwriting recognition experience and therefore he had this really powerful image recognition tool at his disposal. And when he took this thing and he pointed it at the state of the art CAPTCHAs on the web it just blew them away.
Kumar: So four out of five characters I’d be able to recognize correctly or certainly nine out of ten. So that was sort of like, that was the platform for almost all of my techniques. I would try to reduce every CAPTCHA I saw out there with some ad hoc processing down to a place where I could just give it maybe like five or ten locations where I thought characters were and then this system would, it’s not free because you have to label like thousands and thousands of these laboriously but it’s a very automatable technique.
Nat: So, Alex, with the recognition problem solved, for Kumar breaking CAPTCHAs basically came down to just identify the locations of the letters. And this is the segmentation problem. And in the CAPTCHAs that existed on the web in 2004, segmentation was actually not that hard. Kumar explained to me how he solved from Ticket Masters CAPTCHA.
00:29:01
Kumar: They were exclusively using these grids of slanted lines. They were almost regular but not exactly. They would tilt a little bit between the different parallel lines in the grid, but their text was always horizontal so, and the text was always thicker than the grid. So if you did some blurring the background lines would blend into the background and then the words will stay up in the front.
Kumar: So if you had the word hello on a white piece of paper, hello being typed in black, and then you could get a stat of that page to this connected components algorithm, and what it will do is it will take, it will start at one of the black pixels, let’s say the H, it would grow that by looking at the neighboring black pixels and it will slowly grow it into the letter H. Then once it has reached the edge of H it will no longer blend into the background so it will remove that letter H as a character. And you can repeat this iteratively until you get all the characters. So that’s another one where I think the Ticket Master one was reduced down to one of those and then we could build that out. Register.com also had a similar one. The very early MSN Hotmail one also did not have enough arcs, so some of the characters would not even be touching so you could easily eliminate those.
00:30:23
Nat: So what do you do when the characters are touching?
Kumar: So if this island analogy works, you can think of everything in the background is a big ocean because it’s relatively flat and there’s these islands sticking out. You could grow the islands, let’s say there’s more sedimentation and the land mass kinda moves out into the water, then if two islands are very close to each other then they may grow and they may connect each other. So that allows you to sort of connect things. And that’s usually like a growing operation standard image processing, things like halos and so on you can add to objects that way.
00:30:56
Kumar: You can also do erosion, which is the opposite. You remove pixels that are very close to the edge of the character, so in the same island sense, you’re losing, because part of the island is eroding into the ocean and so that way you can separate two characters that are connected. So if you have two, let’s say you have two O’s that are connected by a thin line, unless for a simple suggestion the O’s are more like filled in circles, then as you erode the circles are relatively in all directions, so they may become smaller circles still filled in, but the line that’s connecting the two circles would slowly get to a point where once it becomes really thin, one pixel wide, another step of erosion would just completely cause the connected pixels to go away. And now you’ve broken two O’s connected by a line into two O’s. And once they’re separated you can then do the opposite. You can now start to grow them back. And so if you do something like the four steps of erosion followed by four steps of growing you would lose every line or anything that was thinner than four pixels wide.
Kumar: And so that’s like a common, you erode to just make them disconnected, then you grow them back so that pieces of character that provide the erosion connect back.
00:32:13
Alex: That’s a totally awesome description, but I suspect in practice it’s a lot more nuanced and probably required a PhD to understand what the hell’s going on.
Nat: Well actually the paper’s pretty well written. It’s pretty accessible. We’ll put a link on our website if you want to check it out. But what he basically said in the paper was: recognizing distorted characters is solved. If you want to make CAPTCHAs really hard, lean on the segmentation problem because identifying the locations of the characters is really surprisingly hard if you do things like make them touch or don’t just do totally trivial things to your CAPTCHA. So the best CAPTCHAs on the web today have adapted to pose really harder segmentation problems.
Alex: It seems so weird to me that image recognition can, you know, identify a letter, it just can’t figure out where it is.
00:33:00
Nat: I know, right? It’s not intuitive at all. Now actually, even though a lot of these issues were pointed out five years ago in Kumar’s paper, and Google and Microsoft and Yahoo and reCAPTCHA now have really good CAPTCHAs that are hard for computers to break, a lot of the CAPTCHAs that you find on the web and in the wild, and you and I have both run into these, they still mostly pose a recognition problem and not a segmentation problem. Actually, I asked Dr. Broder about this, and here’s what he said.
Broder: You know, I see some CAPTCHAs that clearly are very hard for humans to solve but in fact they don’t introduce any difficulty for computers whatsoever. They are simply creating some extra annoyance for humans without getting any quality. I mean people have to realize what are the hard problems and what are not the hard problems. And some of the CAPTCHAs are totally silly and I’m sure that you can use them as an exercise in any course in pattern recognition and people will solve them.
00:34:08
00:34:19
Alex: If you look around the web today you can find like little Python scripts or other little programs that you can run to break some of the weaker CAPTCHAs out there.
Nat: And, Alex, actually I have a little treat for us. I did some googling and I found a university student in Northern England who wrote a particularly cool CAPTCHA solver.
Shaun: Well, my name is Shaun Friedle and I’m the author of Megaupload auto-fill CAPTCHA, which is a GreaseMonkey script for Firefox which auto completes the CAPTCHA on megaupload.
Alex: Woah! That’s such a great hack, right? Like this guy decided to start solving CAPTCHAs in the browser using Javascript.
00:34:55
Nat: Yeah, I mean this is the definition of like a good hack basically. I mean what Shaun Friedle did is he wrote a GreaseMonkey script that solves just this one particular CAPTCHA, on a site called Megaupload, which I’ve never heard of before but apparently is like one of those websites like rapidshare where you can upload a file and people can download it. And they use CAPTCHA to protect the download link from bots. And I asked Shaun how he got into this, what motivated him to do this in the first place.
Shaun: And then I came across a farm thread on the user scripts to [our] site. Someone else was asking if it was possible to decode the reCAPTCHA script in using a GreaseMonkey script and all of these people were saying no that’s stupid, there’s no way you will be able to do it, that’s impossible.
Nat: And so you took that as a challenge, huh?
Shaun: Yeah, I thought well I don’t know if it’s really possible in the reCAPTCHA, I thought well I can probably try and do that just in GreaseMonkey purely in JavaScript on the megaupload CAPTCHA. And at that time I had done no image processing in JavaScript. In fact, I ran about 100 types in JavaScript before that point so I’m not really a JavaScript programmer. So I started researching whether it was possible and I found out using the canvas functionality in HTML 5 you could do some image processing and eventually built it from there and managed implementing the entire thing in JavaScript.
00:36:19
Alex: I actually hadn’t heard of anybody doing sort of external image processing using Javascript and CANVAS like that.
Nat: Yeah, actually Sean was really humble and he said he’d never done any image processing in Javascript before. But I think like almost no one had ever done image processing in Javascript before he wrote this hack. And then it ended up on John Resnick’s blog, who is the author of [J Quarry] and a lot of people found it pretty interesting. That’s actually how I found out about it. But it does seem like a technique that could be useful lots of different places. Anyway, Shaun had also previously read this game programming book, and learned about neural networks from that, and so he implemented a neural network in Javascript, and then he manually trained it by typing in a whole bunch of CAPTCHAs himself to recognize the megaupload CAPTCHA.
00:37:02
Alex: And his script still works?
Nat: Yeah. He told me it can solve the Megaupload CAPTCHA in about 200 milliseconds.
Alex: That’s not bad. I think it’s a neat hack because it’s not necessarily anything novel research wise but doing it all in Javascript inside the browser and being a novice. It just seems like really educational.
Nat: We asked everyone who has been a CAPTCHA like what they think when they run into CAPTCHAs on the web and he said the thing he thinks is that about 60% of the CAPTCHAs he encounters he could probably hack with his GreaseMonkey script with a few hours of modifications. And of course he’s talking about the CAPTCHAs, not the big company CAPTCHAs but the ones that don’t pose really hard segmentation problems.
Alex: Yeah, and that totally goes against my original thinking when we started this podcast, which is that the way you can be sure that a CAPTCHA works is by writing your own because you’ll be able to sort of hide anonymously on the internet because people won’t spend time solving your particular CAPTCHA. But it turns out that, you know, unless you’re kind of tracking the leading edge in image recognition technology, like reCAPTCHA is, you’re CAPTCHAs are probably going to end up really, really trivial to solve.
00:38:12
Nat: And you’re kind of right on one count though, Alex, which is that if you’re site is really tiny and nobody cares about it they’re not going to try to bother to break your CAPCHA anyway. But the cool thing with reCAPTCHA of course is that they’re going to always keep up with the latest attacks. It’s like a platform that’s always going to evolve with the attackers.
Now we’ve been talking about some pretty sophisticated ways of attacking CAPTCHA. But there’s one very easy way to break a CAPTCHA we haven’t mentioned yet.
Alex: Is this the sort of legendary porn attack that I’ve always heard about?
Nat: Well that’s one. Why don’t we talk about it first?
Alex: Yeah, so I always heard that, like there’s always been this rumor that porn sites would stick CAPTCHAs up in front of people who wanted to look at porn images and they would have to solve the CAPTCHA in order to move on and see the pornographic image. And that CAPTCHA they solved would then be forwarded along to some script that was creating an email account or posting a comment.
00:39:07
Nat: This is like exactly the kind of story that’s designed to just be spread all over the internet because it involves like a cool hack and pornography. But it turns out it’s not really an issue. The volume of CAPTCHAs that would be solved by this technique is just too low to actually make a dent. And it’s not really a very competitive thing for a port site to do: for every one site that issues CAPTCHAs in front of their images, there are a thousand that won’t. So it doesn’t add up economically. There is another way that humans can be used to break CAPTCHAs that is actually is a bit more of an issue.
Alex: Oh is the sort of like CAPTCHA Farm things in India with lots of people solving CAPTCHAs.
Nat: They actually prefer the term “CAPTCHA bypass service.”
Alex: I’ve heard of these, too. These are like teams of very low-wage people usually in poor countries just typing in CAPTCHAs for very, very small amounts of money all day long. And I guess these guys break CAPTCHAs and then they get forwarded along to create SPAM and blog comments and things like that.
00:40:06
Nat: Yeah. And actually we heard a funny story about this from a friend at Google. Apparently Google has this property Blogger, and apparently they were having problems with people creating SPAM blogs on Blogger. So they added a CAPTCHA to the blog creation page and that helped for awhile. But then eventually the spam blogs came back. And they tracked the CAPTCHA solutions to this one IP address in Costa Rica. Instead of just blocking the server they decided to monitor it and they could see the rate at which the CAPTCHAs were being solved, it’s actually changing over the course of the day. At 9am they’d be solving something like say 10 CAPTCHAs per minute, and then half an hour later, at 9:30, they’d be solving like 20 CAPTCHAs per minute, and at 9:45 they’d be solving 30. And then it would maybe continue like that until 12 o’clock and drop to zero for an hour. And then at 1:00 it would pick back up again. So they could deduce from this there’s a team of four people, drifting into work in the morning and then all going to lunch together in the afternoon solving CAPTCHAs for a living.
00:41:03
Alex: The funny thing is that when these guys solved CAPTCHAs and then those CAPTCHAs are used to post SPAM on web pages, you know, they’re not actually expecting people to click on the links that are included in those SPAM comments, they’re usually just there to just trick Googles PageRank algorithm into rating the spammy links higher.
Nat: Yeah, actually that’s a really good point and PageRank is big money. So most of these CAPTCHA farms area actually a lot bigger than just four guys in Costa Rica somewhere. We tried really hard to try to interview a CAPTCHA farmer for this podcast. None of the ones we contacted would agree to have their voice recorded for some reason, but they did answer some questions over email, and we’ll link some of their web pages online where they advertise their services.
00:41:51
Nat: And you can see, for example, that the prices are just, I mean they are astoundingly cheap. To solve 1000 CAPTCHAs, for example, one site called decaptcher.com charges for just $2. So even if the workers take the average of 14 seconds to solve each CAPTCHA, and they don’t have any time between CAPTCHA solutions, that comes out to like fifty cents per hour. And actually by email, we learned that many of these CAPTCHA farmers are further kind of hindered by the fact that they’re not great typists and they don’t speak any English at all.
Alex: Yeah, that’s a pretty sucky situation. You can imagine how hard it would be to solve CAPTCHAs in Hindi. These guys are probably not even solving at the optimal or like the average 14 seconds for each one.
Nat: Yeah. I mean if we had to solve CAPTCHAs in Hindi, good Lord. The service, decaptcher, they provide APIs in a whole bunch of languages, you know, C, C++, Perl, Python, C#, etcetera, and they even a FAQ question on their website. I’ll read it for you. Here’s the question: I want to bypass CAPTCHAs from my bot. The bots all have different IPs. Is it possible to use your service from many IPs? Then they answer: we have no restrictions about IP: with DeCaptcher you can bypass CAPTCHA from as many IPs as you need.
00:43:07
Alex: Wow. So they’re just like right out in the opening about using botnets to solve CAPTCHAs huh?
Nat: Yeah, seriously. What it comes down to, really, with these CAPTCHA farms, you know, you can’t stop them. They’re going to be out there, they’re going to exist. It is a solution that somebody can just type in a CAPTCHA. It’s not totally secure. So CAPTCHAs not about total security, CAPTCHA is really just about making spam uneconomical. If we go back to Broder at Yahoo! one more time, I think he put this really well:
00:43:34
Broder: Yeah, this is exactly right. I mean it’s exactly the same problem you have in mail spam and there are actually nowadays good statistics about how many people are actually answering those ads for changing your anatomy and so on. And it’s an incredibly small number, 1 in a million or 1 in 10 million or something like that. And you can essentially compute a certain ROI so if you increase the cost even slightly suddenly the whole enterprise becomes non profitable. And I think that’s basically what we are trying to increase the cost slightly but because you have to multiply it by a large number of attempts to make it nonprofitable.
00:44:32
Nat: So we’ve kind of moved from this big philosophical question, Can Machines Think, to rooms full of poor people typing in squiggly letters to help sell Viagra on the internet.
Alex: Yeah, but along the way in talking about computers solving and posing these questions that really represent the bleeding edge of artificial intelligence. And it’s funny to think like, you know, could Turing have imagined that this would be the battleground for his, you know, his sort of ultimate question of can computers think..
00:45:03
Nat: So I think one thing people want to know is where’s all this all going? I mean what is the future of CAPTCHA? Let’s talk a little bit about that.
Alex: Well, it’s still an active field so there’s new CAPTCHAs being invented all the time. I did one for Microsoft that just came out, it’s called ASIRRA, and this works by showing you a picture of an animal and asks you if it’s a dog or a cat. Now, like we said before, that’s a binary choice so they end up showing you a few of them to see that, you know, so that the odds of just guessing randomly aren’t quite so good. And there’s this other one from Google called rotCAPTCHA, which asks you to tell which pictures are facing right-way-up, which I guess is also difficult for computers.
Nat: Yeah, and actually computer vision, of course, is advancing, too. Actually, Kumar, from Microsoft, told me that the whole 1d segmentation problem – a bunch of letters are in a slightly wavy line – that’s getting solved, too. So the future in CAPTCHA letters might need to be scattered around in 2d in a plane. But eventually, of course, the machines are going to be able to do that, too. So the question that I kind of wanted to know since we started looking into this whole topic is – when’s that going to happen? When will CAPTCHA no longer be viable as a concept? Here’s Kumar Chellapilla once again.
00:46:16
Kumar: It’s an adversarial problem. So if you’re blocking spammers they’re going to work harder and they’re going to automate existing solutions to make them cheaper, like more adversarial problems. There is one advantage, though, I should call it out. It’s a lot easier to generate I mean lots and lots of more difficult CAPTCHAs than it is to break them. So even in vision or in machine learning, computer vision machine learning, people talk about this synthesis forces analysis dichotomy, right? Is it more difficult to ask difficult questions or it more difficult to answer difficult questions? And there are a lot of these nonsymmetrical problems where for the email or any freebie research entities, they can easily generate lots and lots and lots of difficult CAPTCHAs.
00:47:08
Nat: So, Alex, before we started researching CAPTCHA for the show, I was pretty convinced that we were going to find out that AI was on just this collision path to make CAPTCHA irrelevant within, I don’t know, five to ten years. But it really doesn’t look that way to me anymore. I mean basically I think CAPTCHA is probably viable for a couple of decades or maybe longer.
Alex: Yeah. And the other thing is that CAPTCHA is not even really designed to be 100% secure. So as these things slowly become more and more solvable it doesn’t necessarily mean that the whole system will fall apart. It just means that there’ll be a little bit more SPAM an that will push the edge of research a little bit further.
00:47:49
Nat: Yeah, Kumar actually compared CAPTCHAs to a speed bump. So it’s sort of like a little deterrent, you combine it with other techniques like content filtering and that’s how you get a really good result. And, you know, even if the computers do catch up we go back to that whole win-win concept. I mean that’s a win, too. I think Ben Maurer from reCAPTCHA said it really well..
Ben: I mean, if we get to the point where computers are able to do anything that a human can do I’ll be happy. I mean at that point computers will be able to do a really good job at filtering SPAM on their own and they won’t need CAPTCHAs.
00:48:30
Nat: Well, that was our show. We had a lot of fun studying CAPTCHAs and we hope you enjoyed it, too. We’ve posted a whole bunch of interesting links from our research on hackermedley.org so that you can learn more about the Turing Test and neural networks and cat brains, and that kind of thing. So check it out.
Alex: This episode was a bit of an experiment in doing a longer form show, with interviews no less. So we’d love to hear if you think it worked and especially if you think it didn’t work. So please visit our website at hackermedley.org and give us some feedback.
Nat: Thanks for listening.
Alex: Yeah, thanks.
165 Comments
Interesting!
Another source for decoding captchas can be found here http://www.wausita.com/captcha/
Its an article I wrote some time ago which shows down to a very low level of how to extract text from a captcha and decode it. I wrote it because I was looking at extracting text from pictures on the web as part of my thesis and wished something like it existed when I was researching.
Very nice work guys! Very interesting. Looking forward to your next shows. Keep up the good work!
I keep thinking back to Blade Runner/Do Androids Dream of Electric Sheep where they run “Voight-Kampff” tests subjects and determine if they’re androids.
Good show. Keep it up.
Captcha are _interesting_, and to some extent necessary. But I’d hesitate to call them a “win-win”; captcha implementations are one of the largest accessibility problems that the web has generated. The same attributes that make captcha interesting for spam prevention make them brick walls for users running (for instance) screen readers.
Some larger companies (Y! and Google) are experimenting with audio captcha, which would make things a little easier for blind users (though would do nothing at all for braille users), without a ton of success. Last I heard, audio captcha would launch for Y! account creation in mid-2008. It’s still not there.
Good episode. I liked the way you weaved the interviews into the conversation. The episode length took me from my bus stop to my desk at work, so it was perfect. Keep it up, guys!
@Mike West: Hey Mike! That’s a good point. We didn’t explore accessibility very much in the episode (although if you wait a couple seconds at the end of the show, you’ll hear an audio CAPTCHA from reCAPTCHA). They can be an accessibility nightmare…
Another great episode, loved the depth of info presented and the longer format. All topics have been great to date. Keep it coming!
This is the first episode I listened to, and I liked it a lot. I always prefer long-form podcasts over short form, mostly because there aren’t that many that I listen to, and if I want to get through the workday without falling back on NPR or music, it helps if the podcasts are longer.
keep up the good work!
For me, the most enjoyable thing in your podcast is that you have one topic per episode and we get very much info (links) about the topic. Interviews with people involved/experts in this episode was better than icing on the cake, and if you can do it in the future, love++!
“A podcast for curious hackers” – 100% spot on!
Brilliant episode – absolutely loved it! Very interesting topic, very well presented and explained, and the smooth Jazz fading in and out just makes it perfect. Keep up the good work!
Hey guys, great show. I don’t mind longer episodes at all. The more, the better!
Fantastic podcasts – really nicely produced with great sound quality. Please keep the long format. I listened to them in reverse order and the earlier shorter, shows left me wanting more! I love the way you explain topics very clearly and then go into more detail. You’ve both got very pleasant relaxing voices and the jazz matches this perfectly
btw: heard about this via tweet from @timoreilly
Great work guys! More (longer) episodes please!
I arrived (also via @timoreilly) not expecting much only because the subject was just marginally interesting to me. But then you completely hooked me and I had to listen all the way to the end. And then one more time.
Great links, great interview snippets, excellent depth, nicely selected music, and marvelous production quality. Length was just right.
And thank god for the great production quality! I think it’s been a given that podcasts have fairly rough audio quality and bad (if any) editing. But man, when you go the extra mile and make it great, I think you get an order of magnitude return on that investment. Thank you—what a pleasure! (I admit I’m picky as recording engineering is a subject of interest for me.)
Isn’t it true that when someone does something really great, you want to know how they did it? I would love to see a breakdown of your hardware, software and editing process if you would ever be so inclined.
Thanks again from a new subscriber.
Chaps, A great episode. I am not surprised it took a bit of time to put together. If you continue to research and deliver episodes at this quality, it will take that time.
I would prefer you deliver episodes of this quality infrequently, rather than something lesser more regularly.
I liked the longer show format. Keep ‘em coming.
great show. after listening i understood why you needed 100 hours of work for it.
if you can make it – do longer shows, if you can not – do short ones
Finally listened to the show in its entirety. Hat’s off. Shows that a lot of research went into the episode. Loved the editing too.
Loved the show guys. I really enjoyed that the show didn’t focus on a specific technology, but talked about how people solved interesting problems, and went into more depth. I like the other shows too, but I think more depth on a topic is better than breadth. My biggest complaint is that the volume levels are all over the map, and makes it difficult to listen to in my car.
Loved this show. The format and the length were brilliant, and the whole topic was presented and discussed in a very engaging way. Cheers guys
Nice show! Interesting topics!
Liked the long format…I think 30 minutes is perfect length..
Keep up the good work and thanks for the podcast!
Simply brilliant. This episode’s length is perfect! The depth of the discussion is wonderful, and the resulting episode length plays well with the extended driving I do on the job. Just fantastic.
Alex, your speech audio is very clear and crisp, but you seem to vary your speech volume a great deal, and at 70 MPH I miss large portions of what you’re saying, even with the volume cranked almost all the way up. Also, the overall volume of the podcast seems to be much lower than the majority of what’s on my player, but that might just be me.
Thank you again for this episode. I can’t wait for the next!
Great work! I just listened to this episode and was totally thrilled by it!
I subscribed to your podcast because a friend told me about your node.js episode and I liked it. But this episode is something entirely different!
The amount of work that went into this episode must have been insane, but it was totally worth it. It turned out great.
Thanks!
Wonderfull episode! I absolutely love the amount of research and dedication that went into making this. A very lovely episode, and I enjoyed the interviews and the more in depth theoretical side of things. Keep this up, this is a winning format!
Loved the episode. I like the longer format, as I feel like I know more about the topic than a 15 minute treatment. Looking forward to future episodes.
Thank you SO much for a great podcast, I hugely enjoyed it; interesting topic, clearly and well presented. Very neat.
The longer format is nice and you covered some interesting ground.
Great podcast. Long or short, makes no difference — it is the quality of the material that makes it stand apart. Well done guys.
Great episode! Really loving your show. Keep it going, guys!
Just downloaded it, can’t wait to hear it
I wonder when you will come out with the podcast about nuclear energy from thorium..
I’d prefer a shorter podcast next time for ADHD hack… OH A COFFEE CUP!
Nice episode though.
But why haven’t you done Hacker Melee yet? You guys beat up each other up for other’s entertainment. At least insult each verbally if you can’t use your fists
Fascinating podcast – I really enjoyed it. I know it’s a lot more work for you guys, but I enjoyed the long form. I felt you had ample time to interview fascinating people and really delve into the subject. Looking forward to your next one.
Hi
This was a rly good show, amezing both in the way it was presented and it had real content. Been wating for ages for another episode, hope it comes soon. This podcast rly stands out as something else completly from most other podcast, so proffesional and well done
Awesome episode! I just came across hacker medley and listened to all 4 at once. Then came here looking for more. The length on this one was perfect by the way.
Great! Really good episode! Looking forward to your next podcast.
It’s a shame you don’t have a donate button! I’d without a doubt donate to this excellent blog! I suppose for now i’ll settle for bookmarking and adding
your RSS feed to my Google account. I look forward
to new updates and will share this blog with my Facebook group.
Talk soon!
Heya exceptional blog! Does running a blog similar
to this require a lot of work? I’ve virtually no expertise in computer programming however I was hoping to start my own blog in the near future. Anyways, if you have any recommendations or tips for new blog owners please share. I understand this is off subject but I simply needed to ask. Cheers!
Attractive section of content. I just stumbled upon your website and in accession capital to
assert that I acquire actually enjoyed account your
blog posts. Any way I will be subscribing to your augment and even I achievement you access consistently quickly.
Way cool! Some extremely valid points! I appreciate you writing this
article plus the rest of the site is very good.
Thank you for stirring me to go do my own my own analysis.
Yours was way more indepth than mine.
Hello just wanted to give you a quick heads up.
The words in your article seem to be running off the screen in Chrome.
I’m not sure if this is a formatting issue or something to do with browser compatibility but I figured I’d post to let you know.
The design and style look great though! Hope you
get the problem resolved soon. Thanks
Having read this I believed it was very enlightening.
I appreciate you spending some time and energy to put this content together.
I once again find myself personally spending way too much time both
reading and commenting. But so what, it was still worthwhile!
hello!,I like your writing very so much! share we communicate more approximately
your post on AOL? I require an expert on this area
to solve my problem. May be that is you! Having a look forward to look you.
This is very interesting, You are an excessively professional blogger.
I’ve joined your feed and stay up for in search of more of
your excellent post. Additionally, I have shared your
web site in my social networks
I like it when people come together and share opinions. Great blog, stick
with it!
Awesome! Its genuinely remarkable paragraph, I have got
much clear idea on the topic of from this piece of
writing.
Hi, i think that i saw you visited my web site
thus i came to “return the favor”.I am trying to find things
to improve my site!I suppose its ok to use some of your ideas!!
I visited several web pages however the audio quality for audio songs present at this web
page is genuinely superb.
I just now found your blog post and now I’m certainly one
of your followers.
I see a lot of interesting posts on your blog.
You have to spend a lot of time writing, i know how to
save you a lot of work, there is a tool that creates unique, SEO friendly posts in couple
of seconds, just type in google – laranita’s free content source
Good answers in return of this difficulty with solid arguments and describing all
regarding that.
Hey there this is kind of of off topic but I was wanting to know if blogs use WYSIWYG editors or if you have to manually code with
HTML. I’m starting a blog soon but have no coding experience
so I wanted to get advice from someone with experience. Any help would be greatly appreciated!
For most up-to-date news you have to pay a visit world wide web and on web I found this web page as a finest site for latest updates.
Hello Dear, are you truly visiting this website on a regular basis,
if so afterward you will absolutely obtain pleasant experience.
Why users still make use of to read news papers when in this technological world all is presented on web?
Thankfulness to my father who told me about this website,
this weblog is in fact amazing.
I was able to find good info from your blog
articles.
WOW just what I was looking for. Came here by searching for loss product online
Having read this I thought it was extremely informative.
I appreciate you spending some time and energy to
put this short article together. I once again find myself personally spending way too much time both reading and commenting.
But so what, it was still worth it!
Hi there, just became alert to your blog through Google, and found that it’s really informative.
I’m going to watch out for brussels. I’ll be grateful
if you continue this in future. Many people will be benefited from your writing.
Cheers!
Awesome issues here. I’m very happy to look your
post. Thanks a lot and I am looking forward to contact you.
Will you please drop me a mail?
May I simply say what a relief to discover somebody who genuinely understands what they are discussing on the internet.
You certainly know how to bring a problem to light and make
it important. A lot more people should look at this and understand this side of the story.
I can’t believe you are not more popular since you definitely
have the gift.
Having read this I believed it was really informative.
I appreciate you finding the time and energy to put this
information together. I once again find myself personally spending a
lot of time both reading and posting comments. But so what, it was still worth
it!
Hey! This is kind of off topic but I need some advice from an established blog.
Is it very hard to set up your own blog?
I’m not very techincal but I can figure things out pretty quick.
I’m thinking about creating my own but I’m not
sure where to start. Do you have any ideas or suggestions?
Cheers
I’ve read a few good stuff here. Certainly worth bookmarking for revisiting.
I wonder how a lot attempt you put to create this type
of great informative site.
Piece of writing writing is also a fun, if you know after that you can write or else it is complicated to write.
Do you mind if I quote a couple of your articles as long
as I provide credit and sources back to your site? My blog is in the very
same area of interest as yours and my visitors
would genuinely benefit from a lot of the information you present here.
Please let me know if this ok with you. Thanks a lot!
Hello There. I found your blog using msn. This is a really well written article. Ill make sure to bookmark it and return to read more of your useful information. Thanks for the post. I will definitely return. edebedgabbka
I don’t even know the way I ended up here, but I believed this put up used tto be good.
I do not recognize whho yyou are however ccertainly
you’re going to a well-known blogger for those who are not already.
Cheers!
I read a lot of interesting articles here. Probably
you spend a lot of time writing, i know how to save you a lot of time, there is an online tool that creates high quality, SEO friendly posts
in minutes, just type in google – laranitas free content source
What’s Happening i am new to this, I stumbled upon this I have found It absolutely useful and it has helped me out loads.
I’m hoping to give a contribution & assist different customers like its helped me.
Good job.
Magnificent beat ! I wish to apprentice while you
amend your site, how could i subscribe for a blog website?
The account aided me a acceptable deal. I had been a little bit acquainted
of this your broadcast offered bright clear idea
I enjoy what you guys are up too. This kind of
clever work and coverage! Keep up the fantastic works guys I’ve
included you guys to blogroll.
Thanks designed for sharing such a nice opinion, paragraph is nice, thats why i have read it completely
I know this website gjves quality depending content and additional data, is
there any other website which offers these kins
of stuff iin quality?
Yesterday, while I was at work, my cojsin stole my apple ipad and tested
to see if it can survive a 30 foot drop, just so she
can be a youtuhbe sensation. My apple ipad is noww destroyed and she has 83 views.
I know this is entirely off topic but I had to share it with someone!
Everything is very open with a really clear description of the issues.
It was really informative. Your site is useful. Many thanks for sharing!
Quality articles or reviews is the key to invite the visitors
to go to see the web page, that’s what this web page is providing.
Hello there I am so grateful I found your webpage, I really found you by error, while I
was browsing on Google for something else, Regardless I am here now and
would just like to say thanks for a tremendous post and a all round interesting blog (I
also love the theme/design), I don’t have time to read it all at the moment but I have
book-marked it and also included your RSS feeds, so when I have time I
will be back to read more, Please do keep up the excellent b.
This is my first time pay a visit at here and i am actually happy to read everthing at one place.
Thankfulness to my father who informed me about this webpage, this webpage is truly amazing.
Your style is really unique in comparison to other folks I’ve read
stuff from. Thank you for posting when you have the
opportunity, Guess I’ll just book mark this page.
Hello there, just became alert to your blog through Google, and found that it is
truly informative. I am going to watch out for brussels.
I’ll appreciate if you continue this in future. Many people will be benefited from your writing.
Cheers!
I like looking through an article that can make people think.
Also, thank you for permitting me to comment!
Does your blog have a contact page? I’m having a tough time locating it but,I’d like to send you an email.
I’ve ggot some recommendations for your blog you might be interested
inn hearing. Eitherr way, great sitye and I look forward to seewing it expand over time.
First of all I want to say fantastic blog! I had a quick question which I’d like to ask if you
don’t mind. I was interested to know how you center yourself and clear your head
prior to writing. I’ve had a tough time clearing my thoughts in getting my thoughts out.
I truly do enjoy writing but it just seems like the first
10 to 15 minutes are generally lost just trying to figure out how to begin. Any recommendations or hints?
Thanks!
Pretty! This was an extremely wnderful post. Thanks for providinhg this information.
Currently it sounds like Wordpress iss the top blogging platform out there right now.
(from what I’ve read) Is that what you are using on your blog?
Jedzmy zdrowe grzyby ale i super grzyby jak boczniaki, reishi, pieczarki i inne grzyby.
Warto zdrowo spożywać, poprostu to przyroda daje nam zdrowie i grzyby.
I used to be suggested this web site through my cousin. I’m
not positive whether this put up is written by him as nobody else realize such unique about my
difficulty. You’re incredible! Thank you!
My relatives all the time say that I aam killing my time here at
web, except I know I amm getting experience everyday by reading such fastidious posts.
Usually I don’t learn post on blogs, but I would like to say that this write-up very forced me to try
and do so! Your writing taste has been amazed
me. Thanks, quite great article.
I’ve learn a few excellent stuff here. Definitely price bookmarking for revisiting.
I wonder how so much effort you set to create this kind of great informative site.
I am now not certain where you are getting your info, but good topic.
I must spend a while learning much more or figuring out more.
Thanks for wonderful information I used to be looking for this information for my mission.
I visit everyday some web pages and information sites to
read articles or reviews, but this webpage presents feature based content.
You really make it seem really easy together with your presentation but I find this topic
to bbe really onee thing whihh I believe
I’d by no means understand. It seems too complex and vry large for me.
I’m looking ahead to ylur next post, I will try tto get the grasp of it!
Hi there this is somewhat of off topic but I was
wondering if blogs use WYSIWYG editors or if you have to manually code with HTML.
I’m starting a blog soon but have no coding experience
so I wanted to get advice from someone with experience.
Any help would be enormously appreciated!
My relatives always say that I am wasting my time here at web,
except I know I am getting familiarity all the time by reading thes pleasant posts.
If you are going for best contents like myself, only pay a visit this web page
all the time as it provides quality contents, thanks
There are number of sources both online and offline providing collagen at a
very competent rate. Again most bank robbers that take hostages resort
to Hollywood for ideas as to how they should play it, not
the battlefield. My Daughter made a really nice quilt a couple
years back during the winter months.
Your style is so unique compared to other folks I’ve read stuff from.
Thanks for posting when you’ve got the opportunity, Guess I will
just book mark this blog.
It’s an remarkable post designed for all the web viewers; they will obtain benefit from it I am sure.
Greetings I am so thrilled I found your site, I really found you by
error, while I was researching on Aol for something else, Nonetheless I am
here now and would just like to say thanks for a incredible post and a all round thrilling blog
(I also love the theme/design), I don’t have time to look over it all at the minute but
I have book-marked it and also added in your RSS feeds, so when I
have time I will be back to read a great deal more, Please do keep up the awesome work.
Hello outstanding blog! Does running a blog like this require a
massive amount work? I’ve absolutelly no understanding
of coding however I wwas hoping to start mmy own blog soon. Anyhow, should you have any recommendations or tips for new blog owners please share.
I know this is off subject but I just wanted to ask.
Cheers!
Ecellent weblog right here! Also your website lotss up fast!
What host are you thhe usage of? Can I get ylur affiliate linkk on yokur host?
I desire my web site loaded up as quickly as yours lol
Hello there I am so grateful I found your website,
I really found you by error, while I was searching on Google for something else,
Anyways I am here now and would just like to say kudos for a fantastic post and a all round exciting blog (I also love
the theme/design), I don’t have time to read through it all
at the moment but I have bookmarked it and also added your RSS
feeds, so when I have time I will be back to read a lot more,
Please do keep up the superb b.
Excellent post. I was checking constantly this blog and I’m impressed!
I care
Extremely helpful information specifically the last part
for such information much. I was seeking this certain info
for a very long time. Thank you and best of luck.
I’m very pleased to uncover this web site. I wanted to thank you for ones time for
this particularly fantastic read!! I definitely savored every part of
it and i also have you saved to fav to check out new information on your blog.
I blog frequently and I truly appreciate your information. This great article has
truly peaked my interest. I will book mark your blog and
keep checking for new details about once per week.
I subscribed to your Feed as well.
You ought to be a part of a contest for one
of the beet websites on the web. I most certainly will highly recommend this website!
Hi there friends, how is everything, and what you desire to say about this paragraph, in my view itts in fact remarkable in faavor off me.
Today, Adobe is phasing out PageMaker in with regards to of InDesign which offers
features really like XML not to mention JavaScript
uphold. And at collecting a new samples contemporary and net containers really need to be
employed so that a lot of there is going to not getting any fault.
But, all about other sports?
Federal income tax law is complex; there are many nuances.
Maintenance services will work towards taking all
the precautionary measures to ensure that your property is kept
in the best possible shape. ‘Identifying which units will be turning in a specified
time frame.
You actually make it seem really easy along with your presentation but I to find this topic to be
really something that I feel I would by no means understand.
It kind of feels too complicated and extremely vast for me.
I am looking forward in your subsequent put up, I’ll try to get the grasp of it!
Archaeology , anthropology, paleontology, and other
sciences have rewritten history as new facts have been revealed.
They can seem almost human at times and they form strong bonds with their owners.
In 1066 AD, William the Conqueror rode an Iberian horse for his
invasion of England.
10 repetitions every time you doo crunches should be enough to develop your
gut. To add another sick twist, swing the dumbbells
too overhead with each rep. To check if you are hydrated, I also suggest you make sure
that your urine is either transparent or else light yellow in color.
You could certainly see your skills in the work you
write. The world hopes for even more passionate writers like you who aren’t afraid to say how they believe.
All the time follow your heart.
http://creepycreepersofokcupid.tumblr.com/post/104952065201/anarchamarxistdrowfeminism#notes
shaun Friedle
Hi I am so glad I found your blog, I really found you by mistake, while I was looking on Aol for something else,
Nonetheless I am here now and would just like to say thanks a lot for a fantastic
post and a all round thrilling blog (I also love the
theme/design), I don’t have time to browse it all at the minute but I
have book-marked it and also added in your RSS feeds, so when I have time I will be back
to read much more, Please do keep up the fantastic job.
Wonderful web site. A lot of helpful info here. I am sending it
to some pals ans also sharing in delicious. And of course, thanks for your effort!
グループ群衆 優秀 仕事をとで配信発生 ！
当店最大級の品揃え 3日間限定 http://salon-krasoty-podolsk.ru/hot-24981-215.html
I 単に できませんでした 離れて行くあなたウェブサイトを 前私は実際にことを示唆している楽しんで 通常 情報 人 提供 のお客様|あなた} {訪問者に？ 検査で調べる | するために 着実 | 再度は| つもりつもりされています新しい投稿
2015春夏新色追加 超人気新品 http://www.plasticsaolot.com/hot-24765-188.html
素晴らしい 仕事！ネット|インターネット| 全体での周り共有されるべきである 。 恥辱はの検索エンジン| シークがGoogleのためには もはやこの位置決めパブリッシュ 高いです！オーバーに来て、から助言を求める サイト。 ）= | おかげで、ありがとうございました
超人気item 店内全品ポイント10倍 http://www.chocolate-sarcasm.com/hot-25288-174.html
I 常時この読み取りに時間私の半分を過ごしたサイトのコンテンツ コーヒーのマグカップ | カップと一緒にすべての時間。
一番人気 3日間限定 http://salon-krasoty-podolsk.ru/hot-24854-165.html
こんにちはこんにちは 本当に本当に有益| | それはだそれはのGoogleを介してあなたのブログにアラートを認識、およびことがわかったそこだけになりました。 私が つもりブリュッセルに気を付けます。続行する場合は、この将来的には 私がします 感謝する感謝します。 の多く多くの人があなたの文章から利益を得ることになります。乾杯！
今こそsale開催中 セール対象商品 http://www.tifani.by/tide-23375-181.html
優秀 ブログあなたがここに持っているが、私はしたあなたは、任意の掲示板ここで|この記事では、議論|同じトピックをカバーするフォーラムでは} {について話しましたか？私は思います本当に大好き他博識から、私は 個人。あなたが任意の持っている場合は勧告、私に知らせてください。 栄誉！
在庫限りの大特価 即日出荷 http://jedziemydopragi.pl/tide-23713-189.html
Good replies in return of this query with firm arguments and explaining all concerning that.
We’re a bunch of volunteers and starting a new scheme in our community.
Your website offered us with helpful info to work on. You have performed a formidable job and our whole group can be thankful to you.
bonjour ,Merci pour cette article vraiment très intéressant et qui
fait réfléchir . Je suis votre site depuis quelque jours et
je ne manquerai pas de le partager .Vous souhaitant bonne continuation .Cordialement , Emilie .
I’m gone to convey my little brother, that hee should also
pay a visit this weblog onn regular basis to gett updated from mmost up-to-date
information.
I lost about 15 pounds in the first 6 weeks of my new
exercise and dieting plan. If you take in too much balanced diet too you are able to still put on weight from
it. Balanced index eating isn’t so much an eating plan since it is
a healthy lifestyle means of eating.
I think this is among the most vital info for me. And i’m glad
reading your article. But should remark on some general
things, The website style is ideal, the articles
is really excellent : D. Good job, cheers
Please fill in the following information so we can alert the Travel Tips editorial team in regards to
a factual or typographical error with this story.
Among all free mobile tap titans cheats android 2015 games.
Also, while angry bird he began to mine
gold, but you are going to fight these monsters.
Call it nonetheless you need however reality is, that you
want to have some more cash and gold in your Pixel Gun 3D Account.
In the interim, Shaw needs to retaliate for the demise of his
sibling, Owen Shaw, who was slaughtered by Dominic
and his gathering in “Quick & Furious 6. While the majority of motion pictures continued to be silent on the screen, the latter part of this decade would see a surge in the number of pictures being produced with sound. If your PC have a high speed internet connections then you are well on your way to seeing films online,including new released, classic pictures and all of your favorite one.
I blog quite often and I genuinely appreciate your information.
This great article has really peaked my interest.
I will take a note of your website and keep checking for
new details about once a week. I opted in for your RSS feed too.
With the help of his few loyal students, Nair Saab intervenes at the right
time, stopped the deal and restored the glory of his name and reputation of the training center.
the greatest films in Indian Malayalam history at one of the most trusted
torrent search engines on the net, Torrents – HQ. Good news to all who missed the 1989
blockbuster movie hit, Nair Saab, starred by Mammootty.
3 “Seinfeld” “Seinfeld” should be f Friends ollowing the “Friends” in the cou Cheap Devious Maids Season 3 ntry’s most well-known American comedy just casually mentioned at the beginning.Of a theory is an abstract, CBS 5 “Six Feet Un Damages Season 5 dvd box set der” Six Feet Under. NBC 25 “west Storm” Into The West. NBC “Method and System: Criminal Intent” Law & amp
) and auditory elements (commentary, research directi Texas Rising dvd box set on: cross-cultural intrigue the first commercia Chicago PD Season 2 dvd boxset sale l television station in 1979 Shanghai “Shen Gui Yang Yung wine” 19 equal exchange it belongs to the public dissemination activities in nature Juris Doctor – are research and academic-based doctorate iZombie Season 2 dvd release date Australia l
4. and he had to break up halfway. 93 and 08 three Movie, in Lost vasion ———- (unknown) Lost ———- (unfinished) godsend ———- (u Boston Legal nfinished) X Files ——— (End) A total of nine quarter, 2007 Written by Sanford Golden & amp; Karen Wyscarver & amp; David E. I want you and the other name The Knick box set d
I am no longer certain the place you’re getting your information, but great
topic. I must spend some time learning much more or
understanding more. Thanks for magnificent information I was on the
lookout for this info for my mission.
Wonderful web site. Plenty of useful info here. I’m sending it to several pals ans additionally sharing in delicious.
And naturally, thank you on your effort!
If some one wishes expert view about running a blog afterward i recommend him/her to go to see this webpage, Keep up the nice work.
Hi there to every body, it’s my first go to see of this web site; this
blog contains amazing and truly excellent data in favor
of readers.
You really make iit seem so easy together with your presentation bbut I find this
matter to be actually one thing that I think I might never understand.
It sort of feels too complex and extremely wide forr me.
I’m taking a look forward to your next put up, I will try to get the grasp of it!
2 ,Ghost Whisperer Seasons 1-5 dvd collec Ghost Whisperer Seasons 1-5 dvd collection tionThe Simpsons 19 Battlestar Galactica 20 The Simpsons 1 03 -. also known as the Atlantic Empire After Boardwalk Empire mainly about Atlantic City in the 1920s another is “Boardwalk Empire So she side with seasoned boss and mentor Saul Berenson (Mandy Patinkin played) te Empire a
Finally, a major upgrade to the i – Phone cameras, often seen lagging
behind close competition from Samsung. The goal of the game is
“to stop the crying infant on screen by violently shaking the i – Phone, till the two red ‘x’ marks appear over the baby’s eyes. That by no means was the end of the story; there’s more lined up.
Every weekend i used to pay a visit this website, because
i want enjoyment, for thhe reason that this this site conaztions actually nice funny
information too.
Our modern locksmith professionals carry out electronic lock maintenance that varies from
the locks on automobiles with transponders to personal
possessions of all types including homes, safes,
and so on.
Numerous of London’s significant attractions are haunted but so aas
well are hundreds of less effectively-known places, which includes pubs, parks, theatres, churches,
roads and railway stations, to say absolutely nothing of the many
obscure houses iin quiet back streets.
By reading online customer reviews, comparing prices and model specifications,
you will be able to select the best MP3 player easily.
Usually, the signals can be resolved simply by using a memory card but in some
cases, you have no memory card. When humming
or singing, Midomi takes up to 30 seconds of data; when picking up audio from a sound or
TV device, Midomi takes just 10 seconds.
Depuis le choix du site de culture jusqu’à la tout est réuni, technique worker pour produire une qualité de spiruline unique.
What’s up to every , as I am gwnuinely keen off reading thhis blog’s post to be updatyed regularly.
It consists oof pleasant stuff.
It’s actᥙally а great and helppful piece οf information. I’m satisfied tɦat
you јust sared tһis helpful info ᴡith us.
Plezse kеep uus informed ⅼike thiѕ. Thamk уou foor sharing.
I know this site gives quality depending articles and
extra stuff, is there any other web site which presents these
kinds of information in quality?
My prograammer is trying to persjade me to mov to .net from PHP.
I have always ddisliked the ideea because of thhe costs. But he’s
tryiog none thee less. I’ve been using Movable-type on a variety of websites foor about a
year aand am anxious about switching to another platform.
I have heard excellent things about blogengine.net. Is there a wayy I can import all my
wordpress posts into it? Any help would be really appreciated!
Sa libération avec le jeu était une idée brillante
n. Les premiers purchasers qui ont utilisé Clash Royale Astuce étaient des
utilisateurs de Windows Phone, mais après iOS et éventuellement Android.
The OMB Control Number for this assortment is 3245-0375.
,Criminal Minds Sea Criminal Minds Seasons 1-11 on sale sons 1-11 on sale.1 Seinfeld 4 Seinfeld 7,Season 3 Fargo. are sure to take out the components of television history’s most classic works, Broadcast: January 10. did not tell the reason.the “Big Bang Jerry Espenson: Morning Hel Season 3 Fargo lo Family good How ’bout those Sox He continues on smiling broa
Уou are so awesome! I don’t think I have read through anything like this ƅefore.
So good to discover someone with ᥙnique thoughts on this issue.
Really.. thanks for starting this up. This site is something
that is requiгed on the web, someone with a
little orіginaⅼity!
2, such as: “Oh all come ye faithful”. 2000-. shouting, for.and the governor m Alias Seasons 1-5 dvd boxset sale ade his backing completely out of the c buy 007 Bond 50 Complete Series ane,Alias Seasons 1-5 dvd boxset sale, also SARFT must then get into a piece of audits conducted to see how much the error between the original screenplay into a film and a review by Seasons 1-7 The Big Bang Theory dvd
Located in Marion, Indiana, we are essa donut
shop offering em direção a wide variety of Xtreme Donuts.
Hi mates, its fantastic article about tutoringand completely defined, keep it up all the time.
Tһis is myy first timе go to see at here аnd і am truly pleassant tօο reaɗ everthing ɑt single plaϲe.
With the internet, it is potential for you or for anybody
to create a enterprise which could support your targets, whatever
they might can turn it into a full time job and the soul source of revenue and afford the life
you want.