Bitcoin Forum

Hello,
what captcha solution are you using on your sites? I personally hate reCaptcha as I have big problems to read text(bot will probably read it better then me in near future) so I am thinking about SecureImage - do you thnk it's sufficient (= non crackable in short term)

Captcha is very annoying for the end-user of the system. SecureImage looks decent, but it is definitely crackable. The sample captchas look very easy to me - a computer program would be able to solve them this year. You may want to try something unlike captchas, there are different ways to do the turing test.

Whatever replaces the Captcha, I hope it's easier for humans to use than trying to make out whether that's a "d" or a c and an l. That and the time it takes for me to type it in are the only things that are really annoying about it to me.

The jumbled words are ridiculous to deal with sometimes.

I don't mind the simple image ones with a couple numbers in them.

Solvemedia  is pretty decent. You can do secure captchas or profitable ones. Personally, I'd like to see the secure ones used.

http://solvemedia.com/publishers/captcha-type-in

I share this opinion with you. But I would love to be sure about secureImage - do you know about some real break that happened?



This look great - unfortunately it seems it's english only and my clients usually need localized version(as many of their clients don't know english) :-(


I found interesting no-captcha alternative with localization support, but it alos seems to me it is possible to crack it:
http://sweetcaptcha.com/

I think http://www.minteye.com/ is best.
I like it because I don't need to use keyboard for it at all!

So this is combination of advertisement and captcha solving? (good idea if so)

Also it unfortunately seems english only.

Yes, it is ad.
What you mean english only? It is picture so I don't think users have to know english, since you don't have to read anything.
Everything users have to do is use that slider to make image look good, and click enter.

There is example of this chaptcha:

https://i.imgur.com/UziM8r3.png

None of the captchas that involve typing distorted letters into a box are any good.  The best captcha I've run on a website involves 9 changeable images, say animals for example and the question will ask the user to 'select all the cats' out of those pictures of animals.  Easy for a human to solve and not easy for a bot because the pictures switch position every time.   

Visual captchas > text captchas.

I thought there is some description like "Slide this...". But widget you sent seems great!! Surely gonna implement this as one alternative.


Imho partially true. Visual captcha you explain could be cracked after data mining your picture + questions database. That's why I don't beliave in http://sweetcaptcha.com/ I post earlier.

Nope.
But you can add your own text above/under it in any language.

Even better. Thank you man.


And btw I have found possibility to change characteristics of securimage (https://www.phpcaptcha.org/documentation/customizing-securimage/).

I just try to squint hard as i can and try to make out the captcha and hit enter, usually I miss a letter or type the wrong one so it can be annoying when trying to solve these especially on TOR when the languages are different  :o

Interestng point about TOR.  Solving reCaptcha usually its takes me 10-15 tries... hate it :D

I don't understand how those solvemedia ones aren't easily breakable by bots. They don't seem to do much. They are extremely easy to solve and I can't see how they pose a challenge for someone who wanted to break them.

Exactly
If you want a un-crackable captcha you'll need to create one yourself or get a Dev to
Most on the market are extremely easy for a computer to crack

PoW may be able to solve the captcha problem.

Mining is CPU intensive. If a captcha was a script that mined to get a proof with difficultly X, then the cost of creating an account would outweigh the financial benefit of having said account.

Click on "secure" tab - then you can choose difficulty. When I scrolled total right it was unreadable for me :D


But how would real person declare he is actually real??? Imho text captcha is kind of PoW anyway - or maybe better to call it "Proof of understanding"

You can hire a team through mechanical turk to solve proof-of-human captcha. The captcha is solved, but the account is still under automated control or exploited.

If you can attach an expense to an action, an expense which is unnoticed to a single individual taking a single action, but economically inviable to an entity seeking to exploit the action on mass for minor financial gain, then you have solved the problem. (Spam problem)

For some of my sites, I use a combination of 2 tests. One is an addition or subtraction problem. The other is the current btc price listed on the page. So far it has eluded bots but from time to time there is the occasional jackass.

Well i have a question too why the sites uses captcha .. and the company whihc provide cpathca coast for thier capthca?

Sites use chaptchas because it makes spamming and bots action harder.

Yes, reCaptcha is very annoying for the end-user. You can try to use "key captcha":

http://www.energyrebels.com/blog/wp-content/uploads/2011/08/key-captcha.jpg

simple and fast, no text to type, not annoying. But I don't know if it's enough secure or not.

These are probably the least annoying of them all.
I also don't mind solve media usually as they are pretty readable usually.

In first paragraph you said why exactly your second  paragraph is not possible. If it will be easy for single person he can always do it as job to support bot operation. 

The key is the number of repetitions, a single person taking a single action has no noticeable cost involved. Taking multiple actions the cost of production up, if the cost of production (time+electricity) becomes higher than the benefit of having say multiple accounts or spamming, then it doesn't become good business to do so.

It's that same as charging people to submit a form or send an email, there's a monetary value which makes spamming no longer viable.

note: just a random idea, to apply PoW to different problem spaces, could also be used for a voting system, where each vote has to be computationally harder than the last.

It seems very breakable.

no man..

use SolveMedia

it's simple and it even earns you some money ;)

what about a captcha that changes a question every week so that will it make it harder for bot programmers to keep up with the new questions and answers all the time.

SolveMedia has a different captcha everytime..

An automated version of this would be possible, but then again - which spammer would develop a software application for that?

Anyone that evaluate access to system as valuable.

Optimal Captcha- it's number

wtf are you saying?

Optimal captcha is limited use of captcha.

Use no captcha at first then enble it only for users/ips abusing the service

Good point. I will try this stance. I will cover only the most important flows with capthca and on other forms I will use it only for occasions of 3 bad attemps to login etc.

Thank you bitcointalk users. This topic is usefull for me :)