void cchmac_final(const struct ccdigest_info *di, cchmac_ctx_t hc,
unsigned char *mac) {
ccdigest_final(di, cchmac_digest_ctx(di, hc), cchmac_data(di, hc));
/* typecast: output size will alwys fit in an unsigned int */
cchmac_num(di, hc) = (unsigned int)di->output_size;
cchmac_nbits(di, hc) = di->block_size * 8;
ccdigest_copy_state(di, cchmac_istate32(di, hc), cchmac_ostate32(di, hc));
ccdigest_final(di, cchmac_digest_ctx(di, hc), mac);
}
/* The HMAC_<DIG> transform looks like:
<DIG> (K XOR opad || <DIG> (K XOR ipad || text))
Where K is a n byte key
ipad is the byte 0x36 repeated 64 times.
opad is the byte 0x5c repeated 64 times.
text is the data being protected.
*/
void cchmac_init(const struct ccdigest_info *di, cchmac_ctx_t hc,
unsigned long key_len, const void *key_data) {
const unsigned char *key = key_data;
/* Set cchmac_data(di, hc) to key ^ opad. */
unsigned long byte = 0;
if (key_len <= di->block_size) {
for (;byte < key_len; ++byte) {
cchmac_data(di, hc)[byte] = key[byte] ^ 0x5c;
}
} else {
/* Key is longer than di->block size, reset it to key=digest(key) */
ccdigest_init(di, cchmac_digest_ctx(di, hc));
ccdigest_update(di, cchmac_digest_ctx(di, hc), key_len, key);
ccdigest_final(di, cchmac_digest_ctx(di, hc), cchmac_data(di, hc));
key_len = di->output_size;
for (;byte < key_len; ++byte) {
cchmac_data(di, hc)[byte] ^= 0x5c;
}
}
/* Fill remainder of cchmac_data(di, hc) with opad. */
if (key_len < di->block_size) {
CC_MEMSET(cchmac_data(di, hc) + key_len, 0x5c, di->block_size - key_len);
}
/* Set cchmac_ostate32(di, hc) to the state of the first round of the
outer digest. */
ccdigest_copy_state(di, cchmac_ostate32(di, hc), di->initial_state);
di->compress(cchmac_ostate(di, hc), 1, cchmac_data(di, hc));
/* Set cchmac_data(di, hc) to key ^ ipad. */
for (byte = 0; byte < di->block_size; ++byte) {
cchmac_data(di, hc)[byte] ^= (0x5c ^ 0x36);
}
ccdigest_copy_state(di, cchmac_istate32(di, hc), di->initial_state);
di->compress(cchmac_istate(di, hc), 1, cchmac_data(di, hc));
cchmac_num(di, hc) = 0;
cchmac_nbits(di, hc) = di->block_size * 8;
}