annotate src/mac/omac/omac_done.c @ 196:704bb050935f libtomcrypt

makefile fixup for Dropbear
author Matt Johnston <matt@ucc.asn.au>
date Mon, 09 May 2005 12:00:08 +0000
parents 1c15b283127b
children 39d5d58461d6
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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 #include "tomcrypt.h"
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12
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13 /**
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14 @file omac_done.c
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15 OMAC1 support, terminate a stream, Tom St Denis
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16 */
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17
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18 #ifdef OMAC
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19
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20 /**
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21 Terminate an OMAC stream
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22 @param omac The OMAC state
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23 @param out [out] Destination for the authentication tag
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24 @param outlen [in/out] The max size and resulting size of the authentication tag
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25 @return CRYPT_OK if successful
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26 */
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27 int omac_done(omac_state *omac, unsigned char *out, unsigned long *outlen)
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28 {
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29 int err, mode;
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30 unsigned x;
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31
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32 LTC_ARGCHK(omac != NULL);
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33 LTC_ARGCHK(out != NULL);
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34 LTC_ARGCHK(outlen != NULL);
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35 if ((err = cipher_is_valid(omac->cipher_idx)) != CRYPT_OK) {
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36 return err;
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37 }
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38
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39 if ((omac->buflen > (int)sizeof(omac->block)) || (omac->buflen < 0) ||
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40 (omac->blklen > (int)sizeof(omac->block)) || (omac->buflen > omac->blklen)) {
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41 return CRYPT_INVALID_ARG;
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42 }
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43
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44 /* figure out mode */
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45 if (omac->buflen != omac->blklen) {
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46 /* add the 0x80 byte */
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47 omac->block[omac->buflen++] = 0x80;
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48
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49 /* pad with 0x00 */
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50 while (omac->buflen < omac->blklen) {
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51 omac->block[omac->buflen++] = 0x00;
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52 }
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53 mode = 1;
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54 } else {
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55 mode = 0;
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56 }
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57
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58 /* now xor prev + Lu[mode] */
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59 for (x = 0; x < (unsigned)omac->blklen; x++) {
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60 omac->block[x] ^= omac->prev[x] ^ omac->Lu[mode][x];
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61 }
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62
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63 /* encrypt it */
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64 cipher_descriptor[omac->cipher_idx].ecb_encrypt(omac->block, omac->block, &omac->key);
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65 cipher_descriptor[omac->cipher_idx].done(&omac->key);
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66
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67 /* output it */
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68 for (x = 0; x < (unsigned)omac->blklen && x < *outlen; x++) {
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69 out[x] = omac->block[x];
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70 }
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71 *outlen = x;
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72
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73 #ifdef LTC_CLEAN_STACK
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74 zeromem(omac, sizeof(*omac));
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75 #endif
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76 return CRYPT_OK;
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77 }
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78
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79 #endif
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80