RSA Security 5 manual AIRC4BER

AI_RC4_BER

AI_RC4_BER

Purpose:

This AI is similar to AI_RC4 except that it uses the ASN.1 BER format. This AI allows you to parse and create ASN.1 algorithm identifiers such as those used in PKCS #7 and other protocols. You call B_SetAlgorithmInfo to initialize an algorithm object from the encoded algorithm identifier. You call B_GetAlgorithmInfo with this AI to create an encoded algorithm identifier from an algorithm object that was created using AI_RC4 or AI_RC4_BER. The OID for this algorithm, excluding the tag and length bytes, in decimal is “42, 134, 72, 134, 247, 13, 3, 4”.

Type of information this allows you to use:

the encoding of an algorithm identifier that specifies the RC4 encryption algorithm.

Format of info supplied to B_SetAlgorithmInfo:

pointer to an ITEM structure that gives the address and length of the BER-encoded algorithm identifier. The encoding is converted to DER before it is copied to the algorithm object. B_SetAlgorithmInfo returns BE_WRONG_ALGORITHM_INFO if the algorithm identifier specifies an algorithm other than RC4.

Format of info returned by B_GetAlgorithmInfo:

pointer to an ITEM structure that gives the address and length of the DER-encoded algorithm identifier.

Crypto-C procedures to use with algorithm object:

B_EncryptInit, B_EncryptUpdate, B_EncryptFinal, B_DecryptInit,

B_DecryptUpdate, and B_DecryptFinal. You may pass (B_ALGORITHM_OBJ)NULL_PTR for all randomAlgorithm arguments.

Due to the nature of the RC4 algorithm, security is compromised if multiple data blocks are encrypted with the same RC4 key. Therefore, B_EncryptUpdate cannot be called after B_EncryptFinal. To begin an encryption operation for a new data block, you must call B_EncryptInit and supply a new key.

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