关键词: RC4算法, 随机比特产生器, 椭圆曲线, 秘密整数

Abstract:

Aiming at the problem that the key stream sequence of RC4 algorithm is not highly random, and it is vulnerable to fault introduction attack, distinguishing attack and “armed attack”, an improved RC4 algorithm based on BBS generator and elliptic curve is proposed. The algorithm generates a seed key by using a random bit generator and a random large prime number, and generates a secret integer by using an elliptic curve. After each output, the elements in the S box are re-assigned to generate a highly random key stream sequence. The improved RC4 algorithm can pass the NIST randomness test, in which the frequency test, the run test and the Maurer test ratio are higher than the RC4 algorithm by 0.12918, 0.10739, 0.19764, respectively, which can effectively prevent the generation of invariant weak keys and resist the “armed” attack. The key stream sequence is evenly distributed, without deviation, and it can effectively resist the distinguishing attack. The secret integer guessing based on the elliptic curve is difficult to guess, and the internal state of the S box cannot be known, which can resist the “fault introduction” attack. Theoretical and experimental results show that the randomness and safety of improved RC4 algorithm is higher than RC4 algorithm.

Key words: RC4 algorithm, random bit generator, elliptic curve, secret integer