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comparison 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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1470:8bba51a55704 1471:6dba84798cd5
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 */
9 #include "tomcrypt.h"
10
11 #ifdef LTC_CCM_MODE
12
13 /**
14 Process plaintext/ciphertext through CCM
15 @param ccm The CCM state
16 @param pt The plaintext
17 @param ptlen The plaintext length (ciphertext length is the same)
18 @param ct The ciphertext
19 @param direction Encrypt or Decrypt mode (CCM_ENCRYPT or CCM_DECRYPT)
20 @return CRYPT_OK on success
21 */
22 int ccm_process(ccm_state *ccm,
23 unsigned char *pt, unsigned long ptlen,
24 unsigned char *ct,
25 int direction)
26 {
27 unsigned char z, b;
28 unsigned long y;
29 int err;
30
31 LTC_ARGCHK(ccm != NULL);
32
33 /* Check aad has been correctly added */
34 if (ccm->aadlen != ccm->current_aadlen) {
35 return CRYPT_ERROR;
36 }
37
38 /* Check we do not process too much data */
39 if (ccm->ptlen < ccm->current_ptlen + ptlen) {
40 return CRYPT_ERROR;
41 }
42 ccm->current_ptlen += ptlen;
43
44 /* now handle the PT */
45 if (ptlen > 0) {
46 LTC_ARGCHK(pt != NULL);
47 LTC_ARGCHK(ct != NULL);
48
49 for (y = 0; y < ptlen; y++) {
50 /* increment the ctr? */
51 if (ccm->CTRlen == 16) {
52 for (z = 15; z > 15-ccm->L; z--) {
53 ccm->ctr[z] = (ccm->ctr[z] + 1) & 255;
54 if (ccm->ctr[z]) break;
55 }
56 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
57 return err;
58 }
59 ccm->CTRlen = 0;
60 }
61
62 /* if we encrypt we add the bytes to the MAC first */
63 if (direction == CCM_ENCRYPT) {
64 b = pt[y];
65 ct[y] = b ^ ccm->CTRPAD[ccm->CTRlen++];
66 } else {
67 b = ct[y] ^ ccm->CTRPAD[ccm->CTRlen++];
68 pt[y] = b;
69 }
70
71 if (ccm->x == 16) {
72 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
73 return err;
74 }
75 ccm->x = 0;
76 }
77 ccm->PAD[ccm->x++] ^= b;
78 }
79 }
80
81 return CRYPT_OK;
82 }
83
84 #endif
85
86 /* ref: $Format:%D$ */
87 /* git commit: $Format:%H$ */
88 /* commit time: $Format:%ai$ */