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This CAPTCHA (reCAPTCHA v1) of "smwm" obscures its message from computer interpretation by twisting the letters and adding a slight background color gradient.A CAPTCHA (/ ˈ k æ p. tʃ ə / KAP-chə) is a type of challenge–response test used in computing to determine whether the user is human in order to deter bot attacks and spam.
If you can't see the image, make sure your browser preferences are set to display images and try again. Alternatively, you can listen to the image challenge by clicking on the audio icon. Display images in Edge Display images in Safari Display images in Firefox Display images in Google Chrome Display images in Internet Explorer
reCAPTCHA Inc. [1] is a CAPTCHA system owned by Google.It enables web hosts to distinguish between human and automated access to websites. The original version asked users to decipher hard-to-read text or match images.
Challenge-response authentication can help solve the problem of exchanging session keys for encryption. Using a key derivation function, the challenge value and the secret may be combined to generate an unpredictable encryption key for the session. This is particularly effective against a man-in-the-middle attack, because the attacker will not ...
Every pixel from the secret image is encoded into multiple subpixels in each share image using a matrix to determine the color of the pixels. In the (2, n ) case, a white pixel in the secret image is encoded using a matrix from the following set, where each row gives the subpixel pattern for one of the components:
In 2007, von Ahn invented reCAPTCHA, [24] a new form of CAPTCHA that also helps digitize books. In reCAPTCHA, the images of words displayed to the user come directly from old books that are being digitized; they are words that optical character recognition could not identify and are sent to people throughout the web to be identified. ReCAPTCHA ...
He is well known for work on the Isomap embedding algorithm, CAPTCHA challenges, Cover Trees for nearest neighbor search, Contextual Bandits (which he coined [2]) for reinforcement learning applications, [3] and learning reductions. [4] John is the author of the blog hunch.net and the principal developer of Vowpal Wabbit.
Python Imaging Library is a free and open-source additional library for the Python programming language that adds support for opening, manipulating, and saving many different image file formats. It is available for Windows, Mac OS X and Linux. The latest version of PIL is 1.1.7, was released in September 2009 and supports Python 1.5.2–2.7. [3]