RSA Security manual AIMD5WithXOR, Pointer to a Bpbeparams structure

AI_MD5WithXOR

AI_MD5WithXOR

Purpose:

This AI is used for encrypting the file keys. This algorithm implements a variant of password-based encryption. The data being encrypted is XORed with a secret key derived from a password, and it can be successfully decrypted only when the correct password is provided. Since the secret key is a 128-bit output of MD5 message digest algorithm, the data being encrypted should be no longer than 128 bits. A description of MD5 can be found in RFC 1321.

Type of information this allows you to use:

the salt and iteration count for the MD5 With “exclusive or” (XOR) password-based encryption algorithm. The salt is concatenated with the password before being digested by MD5, and the iteration count specifies how many times the digest needs to be run. The count of 2 indicates that the result of digesting password-and-salt string needs to be run once more through MD5. The final digest is XORed with the data to obtain the encryption.

Format of info supplied to B_SetAlgorithmInfo:

pointer to a B_PBE_PARAMS structure:

typedef struct {
unsigned char	*salt;	/* pointer to 8-byte salt value */
unsigned int	iterationCount;	/* iteration count */
} B_PBE_PARAMS;

Format of info returned by B_GetAlgorithmInfo:

pointer to a B_PBE_PARAMS structure (see above).

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.

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