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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
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2 * |
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3 * LibTomCrypt is a library that provides various cryptographic |
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4 * algorithms in a highly modular and flexible manner. |
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5 * |
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6 * The library is free for all purposes without any express |
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7 * guarantee it works. |
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8 * |
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9 * Tom St Denis, [email protected], http://libtomcrypt.org |
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10 */ |
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11 /* OMAC1 Support by Tom St Denis (for 64 and 128 bit block ciphers only) */ |
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12 #include "mycrypt.h" |
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13 |
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14 #ifdef OMAC |
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15 |
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16 int omac_done(omac_state *state, unsigned char *out, unsigned long *outlen) |
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17 { |
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143
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18 int err, mode; |
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19 unsigned x; |
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20 |
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143
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21 _ARGCHK(state != NULL); |
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22 _ARGCHK(out != NULL); |
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23 _ARGCHK(outlen != NULL); |
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24 if ((err = cipher_is_valid(state->cipher_idx)) != CRYPT_OK) { |
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25 return err; |
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26 } |
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27 |
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28 if ((state->buflen > (int)sizeof(state->block)) || (state->buflen < 0) || |
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29 (state->blklen > (int)sizeof(state->block)) || (state->buflen > state->blklen)) { |
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30 return CRYPT_INVALID_ARG; |
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31 } |
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32 |
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33 /* figure out mode */ |
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34 if (state->buflen != state->blklen) { |
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35 /* add the 0x80 byte */ |
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36 state->block[state->buflen++] = 0x80; |
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37 |
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38 /* pad with 0x00 */ |
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39 while (state->buflen < state->blklen) { |
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40 state->block[state->buflen++] = 0x00; |
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41 } |
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42 mode = 1; |
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43 } else { |
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44 mode = 0; |
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45 } |
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46 |
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47 /* now xor prev + Lu[mode] */ |
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143
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48 for (x = 0; x < (unsigned)state->blklen; x++) { |
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49 state->block[x] ^= state->prev[x] ^ state->Lu[mode][x]; |
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50 } |
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51 |
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52 /* encrypt it */ |
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53 cipher_descriptor[state->cipher_idx].ecb_encrypt(state->block, state->block, &state->key); |
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54 |
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55 /* output it */ |
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143
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56 for (x = 0; x < (unsigned)state->blklen && x < *outlen; x++) { |
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57 out[x] = state->block[x]; |
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58 } |
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59 *outlen = x; |
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60 |
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61 #ifdef CLEAN_STACK |
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62 zeromem(state, sizeof(*state)); |
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63 #endif |
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64 return CRYPT_OK; |
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65 } |
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66 |
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67 #endif |
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68 |
