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107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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#include "tomcrypt.h"
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/**
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@file xcbc_init.c
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XCBC Support, start an XCBC state
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*/
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#ifdef LTC_XCBC
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/** Initialize XCBC-MAC state
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@param xcbc [out] XCBC state to initialize
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@param cipher Index of cipher to use
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@param key [in] Secret key
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@param keylen Length of secret key in octets
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Return CRYPT_OK on success
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*/
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int xcbc_init(xcbc_state *xcbc, int cipher, const unsigned char *key, unsigned long keylen)
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{
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int x, y, err;
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symmetric_key *skey;
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unsigned long k1;
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LTC_ARGCHK(xcbc != NULL);
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LTC_ARGCHK(key != NULL);
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/* schedule the key */
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if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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return err;
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}
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#ifdef LTC_FAST
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if (cipher_descriptor[cipher].block_length % sizeof(LTC_FAST_TYPE)) {
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return CRYPT_INVALID_ARG;
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}
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#endif
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skey = NULL;
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/* are we in pure XCBC mode with three keys? */
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if (keylen & LTC_XCBC_PURE) {
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keylen &= ~LTC_XCBC_PURE;
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if (keylen < 2UL*cipher_descriptor[cipher].block_length) {
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return CRYPT_INVALID_ARG;
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}
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k1 = keylen - 2*cipher_descriptor[cipher].block_length;
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XMEMCPY(xcbc->K[0], key, k1);
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XMEMCPY(xcbc->K[1], key+k1, cipher_descriptor[cipher].block_length);
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XMEMCPY(xcbc->K[2], key+k1 + cipher_descriptor[cipher].block_length, cipher_descriptor[cipher].block_length);
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} else {
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/* use the key expansion */
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k1 = cipher_descriptor[cipher].block_length;
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/* schedule the user key */
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skey = XCALLOC(1, sizeof(*skey));
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if (skey == NULL) {
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return CRYPT_MEM;
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}
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if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, skey)) != CRYPT_OK) {
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goto done;
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}
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/* make the three keys */
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for (y = 0; y < 3; y++) {
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for (x = 0; x < cipher_descriptor[cipher].block_length; x++) {
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xcbc->K[y][x] = y + 1;
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}
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cipher_descriptor[cipher].ecb_encrypt(xcbc->K[y], xcbc->K[y], skey);
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}
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}
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/* setup K1 */
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err = cipher_descriptor[cipher].setup(xcbc->K[0], k1, 0, &xcbc->key);
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/* setup struct */
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zeromem(xcbc->IV, cipher_descriptor[cipher].block_length);
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xcbc->blocksize = cipher_descriptor[cipher].block_length;
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xcbc->cipher = cipher;
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xcbc->buflen = 0;
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done:
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cipher_descriptor[cipher].done(skey);
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if (skey != NULL) {
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#ifdef LTC_CLEAN_STACK
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zeromem(skey, sizeof(*skey));
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#endif
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XFREE(skey);
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}
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return err;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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