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annotate libtomcrypt/src/encauth/ccm/ccm_process.c @ 1471:6dba84798cd5

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Update to libtomcrypt 1.18.1, merged with Dropbear changes
author Matt Johnston <matt@ucc.asn.au>
date Fri, 09 Feb 2018 21:44:05 +0800
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1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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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 #include "tomcrypt.h"
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10
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11 #ifdef LTC_CCM_MODE
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12
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13 /**
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14 Process plaintext/ciphertext through CCM
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15 @param ccm The CCM state
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16 @param pt The plaintext
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17 @param ptlen The plaintext length (ciphertext length is the same)
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18 @param ct The ciphertext
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19 @param direction Encrypt or Decrypt mode (CCM_ENCRYPT or CCM_DECRYPT)
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20 @return CRYPT_OK on success
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21 */
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22 int ccm_process(ccm_state *ccm,
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23 unsigned char *pt, unsigned long ptlen,
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24 unsigned char *ct,
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25 int direction)
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26 {
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27 unsigned char z, b;
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28 unsigned long y;
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29 int err;
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30
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31 LTC_ARGCHK(ccm != NULL);
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32
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33 /* Check aad has been correctly added */
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34 if (ccm->aadlen != ccm->current_aadlen) {
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35 return CRYPT_ERROR;
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36 }
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37
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38 /* Check we do not process too much data */
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39 if (ccm->ptlen < ccm->current_ptlen + ptlen) {
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40 return CRYPT_ERROR;
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41 }
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42 ccm->current_ptlen += ptlen;
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43
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44 /* now handle the PT */
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45 if (ptlen > 0) {
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46 LTC_ARGCHK(pt != NULL);
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47 LTC_ARGCHK(ct != NULL);
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48
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49 for (y = 0; y < ptlen; y++) {
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50 /* increment the ctr? */
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51 if (ccm->CTRlen == 16) {
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52 for (z = 15; z > 15-ccm->L; z--) {
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53 ccm->ctr[z] = (ccm->ctr[z] + 1) & 255;
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54 if (ccm->ctr[z]) break;
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55 }
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56 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
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57 return err;
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58 }
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59 ccm->CTRlen = 0;
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60 }
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61
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62 /* if we encrypt we add the bytes to the MAC first */
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63 if (direction == CCM_ENCRYPT) {
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64 b = pt[y];
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65 ct[y] = b ^ ccm->CTRPAD[ccm->CTRlen++];
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66 } else {
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67 b = ct[y] ^ ccm->CTRPAD[ccm->CTRlen++];
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68 pt[y] = b;
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69 }
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70
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71 if (ccm->x == 16) {
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72 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
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73 return err;
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74 }
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75 ccm->x = 0;
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76 }
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77 ccm->PAD[ccm->x++] ^= b;
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78 }
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79 }
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80
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81 return CRYPT_OK;
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82 }
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83
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84 #endif
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85
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86 /* ref: $Format:%D$ */
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87 /* git commit: $Format:%H$ */
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88 /* commit time: $Format:%ai$ */