Propose an Arabic CAPTCHA system based on chaotic maps

Abstract EN

CAPTCHA is the facility that prevents web bots from accessing the web services by generating tests to check whether the user is human or computer program.

In this paper, a new pseudo-random bits generator based on chaotic system is offered to generate Arabic letters and numbers for CAPTCHA system.

The proposed generator uses two Jacobian elliptic Chebyshev rational maps that are combined in the algorithm to produce a block of 32bits in each iteration.

A specified number of bits are selected from the resulted blocks to be converted to a set of Arabic letters and numbers.

National Institute of Standards and Technology (NIST) statistical test suite are used to assess the generator randomness, all tests has been passed except Longest Run of Ones in a Block Test, Binary Matrix Rank Test and Random Excursions Test