1/*
2 * Copyright 2010-2018 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include "internal/cryptlib.h"
14#include <openssl/cmac.h>
15#include <openssl/err.h>
16
17struct CMAC_CTX_st {
18 /* Cipher context to use */
19 EVP_CIPHER_CTX *cctx;
20 /* Keys k1 and k2 */
21 unsigned char k1[EVP_MAX_BLOCK_LENGTH];
22 unsigned char k2[EVP_MAX_BLOCK_LENGTH];
23 /* Temporary block */
24 unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
25 /* Last (possibly partial) block */
26 unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
27 /* Number of bytes in last block: -1 means context not initialised */
28 int nlast_block;
29};
30
31/* Make temporary keys K1 and K2 */
32
33static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
34{
35 int i;
36 unsigned char c = l[0], carry = c >> 7, cnext;
37
38 /* Shift block to left, including carry */
39 for (i = 0; i < bl - 1; i++, c = cnext)
40 k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
41
42 /* If MSB set fixup with R */
43 k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
44}
45
46CMAC_CTX *CMAC_CTX_new(void)
47{
48 CMAC_CTX *ctx;
49
50 if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) {
51 CRYPTOerr(CRYPTO_F_CMAC_CTX_NEW, ERR_R_MALLOC_FAILURE);
52 return NULL;
53 }
54 ctx->cctx = EVP_CIPHER_CTX_new();
55 if (ctx->cctx == NULL) {
56 OPENSSL_free(ctx);
57 return NULL;
58 }
59 ctx->nlast_block = -1;
60 return ctx;
61}
62
63void CMAC_CTX_cleanup(CMAC_CTX *ctx)
64{
65 EVP_CIPHER_CTX_reset(ctx->cctx);
66 OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
67 OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
68 OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
69 OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
70 ctx->nlast_block = -1;
71}
72
73EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
74{
75 return ctx->cctx;
76}
77
78void CMAC_CTX_free(CMAC_CTX *ctx)
79{
80 if (!ctx)
81 return;
82 CMAC_CTX_cleanup(ctx);
83 EVP_CIPHER_CTX_free(ctx->cctx);
84 OPENSSL_free(ctx);
85}
86
87int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
88{
89 int bl;
90
91 if (in->nlast_block == -1)
92 return 0;
93 if ((bl = EVP_CIPHER_CTX_block_size(in->cctx)) < 0)
94 return 0;
95 if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
96 return 0;
97 memcpy(out->k1, in->k1, bl);
98 memcpy(out->k2, in->k2, bl);
99 memcpy(out->tbl, in->tbl, bl);
100 memcpy(out->last_block, in->last_block, bl);
101 out->nlast_block = in->nlast_block;
102 return 1;
103}
104
105int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
106 const EVP_CIPHER *cipher, ENGINE *impl)
107{
108 static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
109
110 /* All zeros means restart */
111 if (!key && !cipher && !impl && keylen == 0) {
112 /* Not initialised */
113 if (ctx->nlast_block == -1)
114 return 0;
115 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
116 return 0;
117 memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(ctx->cctx));
118 ctx->nlast_block = 0;
119 return 1;
120 }
121 /* Initialise context */
122 if (cipher && !EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
123 return 0;
124 /* Non-NULL key means initialisation complete */
125 if (key) {
126 int bl;
127
128 if (!EVP_CIPHER_CTX_cipher(ctx->cctx))
129 return 0;
130 if (!EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen))
131 return 0;
132 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
133 return 0;
134 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
135 return 0;
136 if (!EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl))
137 return 0;
138 make_kn(ctx->k1, ctx->tbl, bl);
139 make_kn(ctx->k2, ctx->k1, bl);
140 OPENSSL_cleanse(ctx->tbl, bl);
141 /* Reset context again ready for first data block */
142 if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
143 return 0;
144 /* Zero tbl so resume works */
145 memset(ctx->tbl, 0, bl);
146 ctx->nlast_block = 0;
147 }
148 return 1;
149}
150
151int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
152{
153 const unsigned char *data = in;
154 int bl;
155
156 if (ctx->nlast_block == -1)
157 return 0;
158 if (dlen == 0)
159 return 1;
160 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
161 return 0;
162 /* Copy into partial block if we need to */
163 if (ctx->nlast_block > 0) {
164 size_t nleft;
165
166 nleft = bl - ctx->nlast_block;
167 if (dlen < nleft)
168 nleft = dlen;
169 memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
170 dlen -= nleft;
171 ctx->nlast_block += nleft;
172 /* If no more to process return */
173 if (dlen == 0)
174 return 1;
175 data += nleft;
176 /* Else not final block so encrypt it */
177 if (!EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl))
178 return 0;
179 }
180 /* Encrypt all but one of the complete blocks left */
181 while (dlen > (size_t)bl) {
182 if (!EVP_Cipher(ctx->cctx, ctx->tbl, data, bl))
183 return 0;
184 dlen -= bl;
185 data += bl;
186 }
187 /* Copy any data left to last block buffer */
188 memcpy(ctx->last_block, data, dlen);
189 ctx->nlast_block = dlen;
190 return 1;
191
192}
193
194int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
195{
196 int i, bl, lb;
197
198 if (ctx->nlast_block == -1)
199 return 0;
200 if ((bl = EVP_CIPHER_CTX_block_size(ctx->cctx)) < 0)
201 return 0;
202 if (poutlen != NULL)
203 *poutlen = (size_t)bl;
204 if (!out)
205 return 1;
206 lb = ctx->nlast_block;
207 /* Is last block complete? */
208 if (lb == bl) {
209 for (i = 0; i < bl; i++)
210 out[i] = ctx->last_block[i] ^ ctx->k1[i];
211 } else {
212 ctx->last_block[lb] = 0x80;
213 if (bl - lb > 1)
214 memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
215 for (i = 0; i < bl; i++)
216 out[i] = ctx->last_block[i] ^ ctx->k2[i];
217 }
218 if (!EVP_Cipher(ctx->cctx, out, out, bl)) {
219 OPENSSL_cleanse(out, bl);
220 return 0;
221 }
222 return 1;
223}
224
225int CMAC_resume(CMAC_CTX *ctx)
226{
227 if (ctx->nlast_block == -1)
228 return 0;
229 /*
230 * The buffer "tbl" contains the last fully encrypted block which is the
231 * last IV (or all zeroes if no last encrypted block). The last block has
232 * not been modified since CMAC_final(). So reinitialising using the last
233 * decrypted block will allow CMAC to continue after calling
234 * CMAC_Final().
235 */
236 return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
237}
238