| /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
| * |
| * LibTomCrypt is a library that provides various cryptographic |
| * algorithms in a highly modular and flexible manner. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| * |
| * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file omac_done.c |
| OMAC1 support, terminate a stream, Tom St Denis |
| */ |
| |
| #ifdef OMAC |
| |
| /** |
| Terminate an OMAC stream |
| @param omac The OMAC state |
| @param out [out] Destination for the authentication tag |
| @param outlen [in/out] The max size and resulting size of the authentication tag |
| @return CRYPT_OK if successful |
| */ |
| int omac_done(omac_state *omac, unsigned char *out, unsigned long *outlen) |
| { |
| int err, mode; |
| unsigned x; |
| |
| LTC_ARGCHK(omac != NULL); |
| LTC_ARGCHK(out != NULL); |
| LTC_ARGCHK(outlen != NULL); |
| if ((err = cipher_is_valid(omac->cipher_idx)) != CRYPT_OK) { |
| return err; |
| } |
| |
| if ((omac->buflen > (int)sizeof(omac->block)) || (omac->buflen < 0) || |
| (omac->blklen > (int)sizeof(omac->block)) || (omac->buflen > omac->blklen)) { |
| return CRYPT_INVALID_ARG; |
| } |
| |
| /* figure out mode */ |
| if (omac->buflen != omac->blklen) { |
| /* add the 0x80 byte */ |
| omac->block[omac->buflen++] = 0x80; |
| |
| /* pad with 0x00 */ |
| while (omac->buflen < omac->blklen) { |
| omac->block[omac->buflen++] = 0x00; |
| } |
| mode = 1; |
| } else { |
| mode = 0; |
| } |
| |
| /* now xor prev + Lu[mode] */ |
| for (x = 0; x < (unsigned)omac->blklen; x++) { |
| omac->block[x] ^= omac->prev[x] ^ omac->Lu[mode][x]; |
| } |
| |
| /* encrypt it */ |
| cipher_descriptor[omac->cipher_idx].ecb_encrypt(omac->block, omac->block, &omac->key); |
| cipher_descriptor[omac->cipher_idx].done(&omac->key); |
| |
| /* output it */ |
| for (x = 0; x < (unsigned)omac->blklen && x < *outlen; x++) { |
| out[x] = omac->block[x]; |
| } |
| *outlen = x; |
| |
| #ifdef LTC_CLEAN_STACK |
| zeromem(omac, sizeof(*omac)); |
| #endif |
| return CRYPT_OK; |
| } |
| |
| #endif |
| |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/mac/omac/omac_done.c,v $ */ |
| /* $Revision: 1.4 $ */ |
| /* $Date: 2005/05/05 14:35:58 $ */ |