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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.com |
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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 xcbc_done.c |
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15 XCBC Support, terminate the state |
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16 */ |
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17 |
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18 #ifdef LTC_XCBC |
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19 |
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20 /** Terminate the XCBC-MAC state |
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21 @param xcbc XCBC state to terminate |
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22 @param out [out] Destination for the MAC tag |
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23 @param outlen [in/out] Destination size and final tag size |
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24 Return CRYPT_OK on success |
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25 */ |
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26 int xcbc_done(xcbc_state *xcbc, unsigned char *out, unsigned long *outlen) |
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27 { |
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28 int err, x; |
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29 LTC_ARGCHK(xcbc != NULL); |
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30 LTC_ARGCHK(out != NULL); |
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31 |
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32 /* check structure */ |
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33 if ((err = cipher_is_valid(xcbc->cipher)) != CRYPT_OK) { |
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34 return err; |
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35 } |
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36 |
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37 if ((xcbc->blocksize > cipher_descriptor[xcbc->cipher].block_length) || (xcbc->blocksize < 0) || |
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38 (xcbc->buflen > xcbc->blocksize) || (xcbc->buflen < 0)) { |
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39 return CRYPT_INVALID_ARG; |
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40 } |
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41 |
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42 /* which key do we use? */ |
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43 if (xcbc->buflen == xcbc->blocksize) { |
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44 /* k2 */ |
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45 for (x = 0; x < xcbc->blocksize; x++) { |
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46 xcbc->IV[x] ^= xcbc->K[1][x]; |
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47 } |
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48 } else { |
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49 xcbc->IV[xcbc->buflen] ^= 0x80; |
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50 /* k3 */ |
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51 for (x = 0; x < xcbc->blocksize; x++) { |
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52 xcbc->IV[x] ^= xcbc->K[2][x]; |
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53 } |
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54 } |
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55 |
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56 /* encrypt */ |
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57 cipher_descriptor[xcbc->cipher].ecb_encrypt(xcbc->IV, xcbc->IV, &xcbc->key); |
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58 cipher_descriptor[xcbc->cipher].done(&xcbc->key); |
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59 |
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60 /* extract tag */ |
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61 for (x = 0; x < xcbc->blocksize && (unsigned long)x < *outlen; x++) { |
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62 out[x] = xcbc->IV[x]; |
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63 } |
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64 *outlen = x; |
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65 |
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66 #ifdef LTC_CLEAN_STACK |
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67 zeromem(xcbc, sizeof(*xcbc)); |
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68 #endif |
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69 return CRYPT_OK; |
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70 } |
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71 |
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72 #endif |
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73 |
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74 /* $Source: /cvs/libtom/libtomcrypt/src/mac/xcbc/xcbc_done.c,v $ */ |
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75 /* $Revision: 1.4 $ */ |
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76 /* $Date: 2006/11/07 03:23:46 $ */ |
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77 |
