3.1.1 Modified Alleged RC4

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This protocol uses a variation of the RC4 algorithm called Modified Alleged Rivest Cipher 4 (MARC4) algorithm.

RC4 algorithm is specified in [SCHNEIER].

MARC4 is different from RC4 as following:

  • Both encryption and decryption MUST use the initialization vector (IV), and IV MUST be the same size as the secret key.

  • A new random IV MUST be generated every time that the data is encrypted. A matching IV MUST be used every time that the data is decrypted.

  • The IV MUST be XOR-ed with the secret key, and the result MUST be used as the secret key for RC4.

  • The first 256 bytes of the key stream MUST be discarded. Subsequent bytes of the key stream MUST be used in the same manner as they are used with RC4.