Outline ![]()
Files ![]()
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
/*
* NIST SP800-38C compliant CCM implementation
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
/*
* Definition of CCM:
* http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf
* RFC 3610 "Counter with CBC-MAC (CCM)"
*
* Related:
* RFC 5116 "An Interface and Algorithms for Authenticated Encryption"
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_CCM_C)
#include "mbedtls/ccm.h"
#include "mbedtls/platform_util.h"
#include <string.h>
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif /* MBEDTLS_PLATFORM_C */
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#if !defined(MBEDTLS_CCM_ALT)
#define CCM_VALIDATE_RET( cond ) \
MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_CCM_BAD_INPUT )
#define CCM_VALIDATE( cond ) \
MBEDTLS_INTERNAL_VALIDATE( cond )
#define CCM_ENCRYPT 0
#define CCM_DECRYPT 1
/*
* Initialize context
*/
void mbedtls_ccm_init( mbedtls_ccm_context *ctx )
{
CCM_VALIDATE( ctx != NULL );
memset( ctx, 0, sizeof( mbedtls_ccm_context ) );
}
int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx,
mbedtls_cipher_id_t cipher,
const unsigned char *key,
unsigned int keybits )
{
int ret;
const mbedtls_cipher_info_t *cipher_info;
CCM_VALIDATE_RET( ctx != NULL );
CCM_VALIDATE_RET( key != NULL );
cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB );
if( cipher_info == NULL )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
if( cipher_info->block_size != 16 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
mbedtls_cipher_free( &ctx->cipher_ctx );
if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 )
return( ret );
if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits,
MBEDTLS_ENCRYPT ) ) != 0 )
{
return( ret );
}
return( 0 );
}
/*
* Free context
*/
void mbedtls_ccm_free( mbedtls_ccm_context *ctx )
{
if( ctx == NULL )
return;
mbedtls_cipher_free( &ctx->cipher_ctx );
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ccm_context ) );
}
/*
* Macros for common operations.
* Results in smaller compiled code than static inline functions.
*/
/*
* Update the CBC-MAC state in y using a block in b
* (Always using b as the source helps the compiler optimise a bit better.)
*/
#define UPDATE_CBC_MAC \
for( i = 0; i < 16; i++ ) \
y[i] ^= b[i]; \
\
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \
return( ret );
/*
* Encrypt or decrypt a partial block with CTR
* Warning: using b for temporary storage! src and dst must not be b!
* This avoids allocating one more 16 bytes buffer while allowing src == dst.
*/
#define CTR_CRYPT( dst, src, len ) \
do \
{ \
if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, \
16, b, &olen ) ) != 0 ) \
{ \
return( ret ); \
} \
\
for( i = 0; i < (len); i++ ) \
(dst)[i] = (src)[i] ^ b[i]; \
} while( 0 )
/*
* Authenticated encryption or decryption
*/
static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len )
{
int ret;
unsigned char i;
unsigned char q;
size_t len_left, olen;
unsigned char b[16];
unsigned char y[16];
unsigned char ctr[16];
const unsigned char *src;
unsigned char *dst;
/*
* Check length requirements: SP800-38C A.1
* Additional requirement: a < 2^16 - 2^8 to simplify the code.
* 'length' checked later (when writing it to the first block)
*
* Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4).
*/
if( tag_len == 2 || tag_len > 16 || tag_len % 2 != 0 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
/* Also implies q is within bounds */
if( iv_len < 7 || iv_len > 13 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
if( add_len > 0xFF00 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
q = 16 - 1 - (unsigned char) iv_len;
/*
* First block B_0:
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv)
* iv_len+1 .. 15 length
*
* With flags as (bits):
* 7 0
* 6 add present?
* 5 .. 3 (t - 2) / 2
* 2 .. 0 q - 1
*/
b[0] = 0;
b[0] |= ( add_len > 0 ) << 6;
b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
b[0] |= q - 1;
memcpy( b + 1, iv, iv_len );
for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
b[15-i] = (unsigned char)( len_left & 0xFF );
if( len_left > 0 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
/* Start CBC-MAC with first block */
memset( y, 0, 16 );
UPDATE_CBC_MAC;
/*
* If there is additional data, update CBC-MAC with
* add_len, add, 0 (padding to a block boundary)
*/
if( add_len > 0 )
{
size_t use_len;
len_left = add_len;
src = add;
memset( b, 0, 16 );
b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
b[1] = (unsigned char)( ( add_len ) & 0xFF );
use_len = len_left < 16 - 2 ? len_left : 16 - 2;
memcpy( b + 2, src, use_len );
len_left -= use_len;
src += use_len;
UPDATE_CBC_MAC;
while( len_left > 0 )
{
use_len = len_left > 16 ? 16 : len_left;
memset( b, 0, 16 );
memcpy( b, src, use_len );
UPDATE_CBC_MAC;
len_left -= use_len;
src += use_len;
}
}
/*
* Prepare counter block for encryption:
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv)
* iv_len+1 .. 15 counter (initially 1)
*
* With flags as (bits):
* 7 .. 3 0
* 2 .. 0 q - 1
*/
ctr[0] = q - 1;
memcpy( ctr + 1, iv, iv_len );
memset( ctr + 1 + iv_len, 0, q );
ctr[15] = 1;
/*
* Authenticate and {en,de}crypt the message.
*
* The only difference between encryption and decryption is
* the respective order of authentication and {en,de}cryption.
*/
len_left = length;
src = input;
dst = output;
while( len_left > 0 )
{
size_t use_len = len_left > 16 ? 16 : len_left;
if( mode == CCM_ENCRYPT )
{
memset( b, 0, 16 );
memcpy( b, src, use_len );
UPDATE_CBC_MAC;
}
CTR_CRYPT( dst, src, use_len );
if( mode == CCM_DECRYPT )
{
memset( b, 0, 16 );
memcpy( b, dst, use_len );
UPDATE_CBC_MAC;
}
dst += use_len;
src += use_len;
len_left -= use_len;
/*
* Increment counter.
* No need to check for overflow thanks to the length check above.
*/
for( i = 0; i < q; i++ )
if( ++ctr[15-i] != 0 )
break;
}
/*
* Authentication: reset counter and crypt/mask internal tag
*/
for( i = 0; i < q; i++ )
ctr[15-i] = 0;
CTR_CRYPT( y, y, 16 );
memcpy( tag, y, tag_len );
return( 0 );
}
/*
* Authenticated encryption
*/
int mbedtls_ccm_star_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len )
{
CCM_VALIDATE_RET( ctx != NULL );
CCM_VALIDATE_RET( iv != NULL );
CCM_VALIDATE_RET( add_len == 0 || add != NULL );
CCM_VALIDATE_RET( length == 0 || input != NULL );
CCM_VALIDATE_RET( length == 0 || output != NULL );
CCM_VALIDATE_RET( tag_len == 0 || tag != NULL );
return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len,
add, add_len, input, output, tag, tag_len ) );
}
int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len )
{
CCM_VALIDATE_RET( ctx != NULL );
CCM_VALIDATE_RET( iv != NULL );
CCM_VALIDATE_RET( add_len == 0 || add != NULL );
CCM_VALIDATE_RET( length == 0 || input != NULL );
CCM_VALIDATE_RET( length == 0 || output != NULL );
CCM_VALIDATE_RET( tag_len == 0 || tag != NULL );
if( tag_len == 0 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
return( mbedtls_ccm_star_encrypt_and_tag( ctx, length, iv, iv_len, add,
add_len, input, output, tag, tag_len ) );
}
/*
* Authenticated decryption
*/
int mbedtls_ccm_star_auth_decrypt( mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
const unsigned char *tag, size_t tag_len )
{
int ret;
unsigned char check_tag[16];
unsigned char i;
int diff;
CCM_VALIDATE_RET( ctx != NULL );
CCM_VALIDATE_RET( iv != NULL );
CCM_VALIDATE_RET( add_len == 0 || add != NULL );
CCM_VALIDATE_RET( length == 0 || input != NULL );
CCM_VALIDATE_RET( length == 0 || output != NULL );
CCM_VALIDATE_RET( tag_len == 0 || tag != NULL );
if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length,
iv, iv_len, add, add_len,
input, output, check_tag, tag_len ) ) != 0 )
{
return( ret );
}
/* Check tag in "constant-time" */
for( diff = 0, i = 0; i < tag_len; i++ )
diff |= tag[i] ^ check_tag[i];
if( diff != 0 )
{
mbedtls_platform_zeroize( output, length );
return( MBEDTLS_ERR_CCM_AUTH_FAILED );
}
return( 0 );
}
int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
const unsigned char *tag, size_t tag_len )
{
CCM_VALIDATE_RET( ctx != NULL );
CCM_VALIDATE_RET( iv != NULL );
CCM_VALIDATE_RET( add_len == 0 || add != NULL );
CCM_VALIDATE_RET( length == 0 || input != NULL );
CCM_VALIDATE_RET( length == 0 || output != NULL );
CCM_VALIDATE_RET( tag_len == 0 || tag != NULL );
if( tag_len == 0 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
return( mbedtls_ccm_star_auth_decrypt( ctx, length, iv, iv_len, add,
add_len, input, output, tag, tag_len ) );
}
#endif /* !MBEDTLS_CCM_ALT */
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
/*
* Examples 1 to 3 from SP800-38C Appendix C
*/
#define NB_TESTS 3
#define CCM_SELFTEST_PT_MAX_LEN 24
#define CCM_SELFTEST_CT_MAX_LEN 32
/*
* The data is the same for all tests, only the used length changes
*/
static const unsigned char key[] = {
0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
};
static const unsigned char iv[] = {
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1a, 0x1b
};
static const unsigned char ad[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13
};
static const unsigned char msg[CCM_SELFTEST_PT_MAX_LEN] = {
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
};
static const size_t iv_len [NB_TESTS] = { 7, 8, 12 };
static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
static const size_t tag_len[NB_TESTS] = { 4, 6, 8 };
static const unsigned char res[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = {
{ 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
{ 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
{ 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
};
int mbedtls_ccm_self_test( int verbose )
{
mbedtls_ccm_context ctx;
/*
* Some hardware accelerators require the input and output buffers
* would be in RAM, because the flash is not accessible.
* Use buffers on the stack to hold the test vectors data.
*/
unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN];
unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN];
size_t i;
int ret;
mbedtls_ccm_init( &ctx );
if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( " CCM: setup failed" );
return( 1 );
}
for( i = 0; i < NB_TESTS; i++ )
{
if( verbose != 0 )
mbedtls_printf( " CCM-AES #%u: ", (unsigned int) i + 1 );
memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN );
memcpy( plaintext, msg, msg_len[i] );
ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i],
iv, iv_len[i], ad, add_len[i],
plaintext, ciphertext,
ciphertext + msg_len[i], tag_len[i] );
if( ret != 0 ||
memcmp( ciphertext, res[i], msg_len[i] + tag_len[i] ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i],
iv, iv_len[i], ad, add_len[i],
ciphertext, plaintext,
ciphertext + msg_len[i], tag_len[i] );
if( ret != 0 ||
memcmp( plaintext, msg, msg_len[i] ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
}
mbedtls_ccm_free( &ctx );
if( verbose != 0 )
mbedtls_printf( "\n" );
return( 0 );
}
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#endif /* MBEDTLS_CCM_C */
Details ![]()
Show: from Types: Columns: ![]( "Show Project Names")
![]( "Show Locations")
![]( "Show Referring Symbols")
![]( "Show Scope")
This file uses the notable symbols shown below. Click anywhere in the file to view more details.