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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 lrw_setiv.c |
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15 LRW_MODE implementation, Set the current IV, Tom St Denis |
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16 */ |
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17 |
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18 #ifdef LTC_LRW_MODE |
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19 |
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20 /** |
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21 Set the IV for LRW |
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22 @param IV The IV, must be 16 octets |
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23 @param len Length ... must be 16 :-) |
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24 @param lrw The LRW state to update |
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25 @return CRYPT_OK if successful |
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26 */ |
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27 int lrw_setiv(const unsigned char *IV, unsigned long len, symmetric_LRW *lrw) |
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28 { |
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29 int err; |
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30 #ifdef LRW_TABLES |
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31 unsigned char T[16]; |
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32 int x, y; |
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33 #endif |
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34 LTC_ARGCHK(IV != NULL); |
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35 LTC_ARGCHK(lrw != NULL); |
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36 |
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37 if (len != 16) { |
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38 return CRYPT_INVALID_ARG; |
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39 } |
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40 |
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41 if ((err = cipher_is_valid(lrw->cipher)) != CRYPT_OK) { |
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42 return err; |
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43 } |
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44 |
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45 /* copy the IV */ |
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46 XMEMCPY(lrw->IV, IV, 16); |
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47 |
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48 /* check if we have to actually do work */ |
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49 if (cipher_descriptor[lrw->cipher].accel_lrw_encrypt != NULL && cipher_descriptor[lrw->cipher].accel_lrw_decrypt != NULL) { |
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50 /* we have accelerators, let's bail since they don't use lrw->pad anyways */ |
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51 return CRYPT_OK; |
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52 } |
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53 |
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54 #ifdef LRW_TABLES |
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55 XMEMCPY(T, &lrw->PC[0][IV[0]][0], 16); |
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56 for (x = 1; x < 16; x++) { |
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57 #ifdef LTC_FAST |
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58 for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) { |
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59 *((LTC_FAST_TYPE *)(T + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][IV[x]][y])); |
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60 } |
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61 #else |
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62 for (y = 0; y < 16; y++) { |
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63 T[y] ^= lrw->PC[x][IV[x]][y]; |
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64 } |
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65 #endif |
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66 } |
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67 XMEMCPY(lrw->pad, T, 16); |
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68 #else |
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69 gcm_gf_mult(lrw->tweak, IV, lrw->pad); |
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70 #endif |
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71 |
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72 return CRYPT_OK; |
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73 } |
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74 |
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75 |
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76 #endif |
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77 /* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_setiv.c,v $ */ |
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78 /* $Revision: 1.12 $ */ |
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79 /* $Date: 2006/06/29 01:53:13 $ */ |
