Chapter 2 Algorithm Info Types 85
AI_FeedbackCipher
AI_FeedbackCipher
Purpose:
This AI allows you to perform various kinds of block cipher encryption or decryption
with feedback. The parameters of this AI include encryption method, feedback
method, and padding method.
Type of information this allows you to use:
a descriptor for block ciphers with feedback, as defined in X9.52.
Format of info supplied to B_SetAlgorithmInfo:
a pointer to a B_BLK_CIPHER_W_FEEDBACK_PARAMS structure:
Format of info returned by B_GetAlgorithmInfo:
pointer to a structure of type B_BLK_CIPHER_W_FEEDBACK_PARAMS.
typedef struct {
unsigned char *encryptionMethodName; /* examples include */
/* “des”, “des_ede” */
POINTER encryptionParams; /* e.g., RC5 parameters */
unsigned char *feedbackMethodName; /*feedback method name, */
/* e.g., “cbc” */
POINTER feedbackParams; /* Points at init vector ITEM */
/* for all feedback modes except cfb */
unsigned char *paddingMethodName; /* padding method name, */
/* e.g., “pad” */
POINTER paddingParams; /* Ignored for now, but may be used */
/* for new padding schemes */
} B_BLK_CIPHER_W_FEEDBACK_PARAMS;