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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 |
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12 /* OCB Implementation by Tom St Denis */ |
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13 #include "mycrypt.h" |
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14 |
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15 #ifdef OCB_MODE |
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16 |
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17 int ocb_done_decrypt(ocb_state *ocb, |
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18 const unsigned char *ct, unsigned long ctlen, |
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19 unsigned char *pt, |
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20 const unsigned char *tag, unsigned long taglen, int *res) |
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21 { |
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22 int err; |
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143
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23 unsigned char *tagbuf; |
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3
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24 unsigned long tagbuflen; |
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25 |
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26 _ARGCHK(ocb != NULL); |
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27 _ARGCHK(pt != NULL); |
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28 _ARGCHK(ct != NULL); |
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29 _ARGCHK(tag != NULL); |
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30 _ARGCHK(res != NULL); |
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31 |
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143
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32 /* default to failed */ |
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3
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33 *res = 0; |
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34 |
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143
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35 /* allocate memory */ |
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36 tagbuf = XMALLOC(MAXBLOCKSIZE); |
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37 if (tagbuf == NULL) { |
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38 return CRYPT_MEM; |
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39 } |
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40 |
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41 tagbuflen = MAXBLOCKSIZE; |
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42 if ((err = __ocb_done(ocb, ct, ctlen, pt, tagbuf, &tagbuflen, 1)) != CRYPT_OK) { |
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143
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43 goto __ERR; |
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3
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44 } |
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45 |
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46 if (taglen <= tagbuflen && memcmp(tagbuf, tag, taglen) == 0) { |
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47 *res = 1; |
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48 } |
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49 |
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143
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50 err = CRYPT_OK; |
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51 __ERR: |
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3
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52 #ifdef CLEAN_STACK |
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143
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53 zeromem(tagbuf, MAXBLOCKSIZE); |
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3
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54 #endif |
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55 |
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143
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56 XFREE(tagbuf); |
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57 |
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58 return err; |
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3
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59 } |
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60 |
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61 #endif |
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62 |
