mbed TLS Build
Dependents: Encypting_Funcional
ccm.c
00001 /* 00002 * NIST SP800-38C compliant CCM implementation 00003 * 00004 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 00005 * SPDX-License-Identifier: Apache-2.0 00006 * 00007 * Licensed under the Apache License, Version 2.0 (the "License"); you may 00008 * not use this file except in compliance with the License. 00009 * You may obtain a copy of the License at 00010 * 00011 * http://www.apache.org/licenses/LICENSE-2.0 00012 * 00013 * Unless required by applicable law or agreed to in writing, software 00014 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 00015 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00016 * See the License for the specific language governing permissions and 00017 * limitations under the License. 00018 * 00019 * This file is part of mbed TLS (https://tls.mbed.org) 00020 */ 00021 00022 /* 00023 * Definition of CCM: 00024 * http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf 00025 * RFC 3610 "Counter with CBC-MAC (CCM)" 00026 * 00027 * Related: 00028 * RFC 5116 "An Interface and Algorithms for Authenticated Encryption" 00029 */ 00030 00031 #if !defined(MBEDTLS_CONFIG_FILE) 00032 #include "mbedtls/config.h" 00033 #else 00034 #include MBEDTLS_CONFIG_FILE 00035 #endif 00036 00037 #if defined(MBEDTLS_CCM_C) 00038 00039 #include "mbedtls/ccm.h" 00040 00041 #include <string.h> 00042 00043 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 00044 #if defined(MBEDTLS_PLATFORM_C) 00045 #include "mbedtls/platform.h" 00046 #else 00047 #include <stdio.h> 00048 #define mbedtls_printf printf 00049 #endif /* MBEDTLS_PLATFORM_C */ 00050 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 00051 00052 /* Implementation that should never be optimized out by the compiler */ 00053 static void mbedtls_zeroize( void *v, size_t n ) { 00054 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0; 00055 } 00056 00057 #define CCM_ENCRYPT 0 00058 #define CCM_DECRYPT 1 00059 00060 /* 00061 * Initialize context 00062 */ 00063 void mbedtls_ccm_init( mbedtls_ccm_context *ctx ) 00064 { 00065 memset( ctx, 0, sizeof( mbedtls_ccm_context ) ); 00066 } 00067 00068 int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx, 00069 mbedtls_cipher_id_t cipher, 00070 const unsigned char *key, 00071 unsigned int keybits ) 00072 { 00073 int ret; 00074 const mbedtls_cipher_info_t *cipher_info; 00075 00076 cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB ); 00077 if( cipher_info == NULL ) 00078 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00079 00080 if( cipher_info->block_size != 16 ) 00081 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00082 00083 mbedtls_cipher_free( &ctx->cipher_ctx ); 00084 00085 if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx , cipher_info ) ) != 0 ) 00086 return( ret ); 00087 00088 if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx , key, keybits, 00089 MBEDTLS_ENCRYPT ) ) != 0 ) 00090 { 00091 return( ret ); 00092 } 00093 00094 return( 0 ); 00095 } 00096 00097 /* 00098 * Free context 00099 */ 00100 void mbedtls_ccm_free( mbedtls_ccm_context *ctx ) 00101 { 00102 mbedtls_cipher_free( &ctx->cipher_ctx ); 00103 mbedtls_zeroize( ctx, sizeof( mbedtls_ccm_context ) ); 00104 } 00105 00106 /* 00107 * Macros for common operations. 00108 * Results in smaller compiled code than static inline functions. 00109 */ 00110 00111 /* 00112 * Update the CBC-MAC state in y using a block in b 00113 * (Always using b as the source helps the compiler optimise a bit better.) 00114 */ 00115 #define UPDATE_CBC_MAC \ 00116 for( i = 0; i < 16; i++ ) \ 00117 y[i] ^= b[i]; \ 00118 \ 00119 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, y, 16, y, &olen ) ) != 0 ) \ 00120 return( ret ); 00121 00122 /* 00123 * Encrypt or decrypt a partial block with CTR 00124 * Warning: using b for temporary storage! src and dst must not be b! 00125 * This avoids allocating one more 16 bytes buffer while allowing src == dst. 00126 */ 00127 #define CTR_CRYPT( dst, src, len ) \ 00128 if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, ctr, 16, b, &olen ) ) != 0 ) \ 00129 return( ret ); \ 00130 \ 00131 for( i = 0; i < len; i++ ) \ 00132 dst[i] = src[i] ^ b[i]; 00133 00134 /* 00135 * Authenticated encryption or decryption 00136 */ 00137 static int ccm_auth_crypt( mbedtls_ccm_context *ctx, int mode, size_t length, 00138 const unsigned char *iv, size_t iv_len, 00139 const unsigned char *add, size_t add_len, 00140 const unsigned char *input, unsigned char *output, 00141 unsigned char *tag, size_t tag_len ) 00142 { 00143 int ret; 00144 unsigned char i; 00145 unsigned char q; 00146 size_t len_left, olen; 00147 unsigned char b[16]; 00148 unsigned char y[16]; 00149 unsigned char ctr[16]; 00150 const unsigned char *src; 00151 unsigned char *dst; 00152 00153 /* 00154 * Check length requirements: SP800-38C A.1 00155 * Additional requirement: a < 2^16 - 2^8 to simplify the code. 00156 * 'length' checked later (when writing it to the first block) 00157 */ 00158 if( tag_len < 4 || tag_len > 16 || tag_len % 2 != 0 ) 00159 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00160 00161 /* Also implies q is within bounds */ 00162 if( iv_len < 7 || iv_len > 13 ) 00163 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00164 00165 if( add_len > 0xFF00 ) 00166 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00167 00168 q = 16 - 1 - (unsigned char) iv_len; 00169 00170 /* 00171 * First block B_0: 00172 * 0 .. 0 flags 00173 * 1 .. iv_len nonce (aka iv) 00174 * iv_len+1 .. 15 length 00175 * 00176 * With flags as (bits): 00177 * 7 0 00178 * 6 add present? 00179 * 5 .. 3 (t - 2) / 2 00180 * 2 .. 0 q - 1 00181 */ 00182 b[0] = 0; 00183 b[0] |= ( add_len > 0 ) << 6; 00184 b[0] |= ( ( tag_len - 2 ) / 2 ) << 3; 00185 b[0] |= q - 1; 00186 00187 memcpy( b + 1, iv, iv_len ); 00188 00189 for( i = 0, len_left = length; i < q; i++, len_left >>= 8 ) 00190 b[15-i] = (unsigned char)( len_left & 0xFF ); 00191 00192 if( len_left > 0 ) 00193 return( MBEDTLS_ERR_CCM_BAD_INPUT ); 00194 00195 00196 /* Start CBC-MAC with first block */ 00197 memset( y, 0, 16 ); 00198 UPDATE_CBC_MAC; 00199 00200 /* 00201 * If there is additional data, update CBC-MAC with 00202 * add_len, add, 0 (padding to a block boundary) 00203 */ 00204 if( add_len > 0 ) 00205 { 00206 size_t use_len; 00207 len_left = add_len; 00208 src = add; 00209 00210 memset( b, 0, 16 ); 00211 b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF ); 00212 b[1] = (unsigned char)( ( add_len ) & 0xFF ); 00213 00214 use_len = len_left < 16 - 2 ? len_left : 16 - 2; 00215 memcpy( b + 2, src, use_len ); 00216 len_left -= use_len; 00217 src += use_len; 00218 00219 UPDATE_CBC_MAC; 00220 00221 while( len_left > 0 ) 00222 { 00223 use_len = len_left > 16 ? 16 : len_left; 00224 00225 memset( b, 0, 16 ); 00226 memcpy( b, src, use_len ); 00227 UPDATE_CBC_MAC; 00228 00229 len_left -= use_len; 00230 src += use_len; 00231 } 00232 } 00233 00234 /* 00235 * Prepare counter block for encryption: 00236 * 0 .. 0 flags 00237 * 1 .. iv_len nonce (aka iv) 00238 * iv_len+1 .. 15 counter (initially 1) 00239 * 00240 * With flags as (bits): 00241 * 7 .. 3 0 00242 * 2 .. 0 q - 1 00243 */ 00244 ctr[0] = q - 1; 00245 memcpy( ctr + 1, iv, iv_len ); 00246 memset( ctr + 1 + iv_len, 0, q ); 00247 ctr[15] = 1; 00248 00249 /* 00250 * Authenticate and {en,de}crypt the message. 00251 * 00252 * The only difference between encryption and decryption is 00253 * the respective order of authentication and {en,de}cryption. 00254 */ 00255 len_left = length; 00256 src = input; 00257 dst = output; 00258 00259 while( len_left > 0 ) 00260 { 00261 size_t use_len = len_left > 16 ? 16 : len_left; 00262 00263 if( mode == CCM_ENCRYPT ) 00264 { 00265 memset( b, 0, 16 ); 00266 memcpy( b, src, use_len ); 00267 UPDATE_CBC_MAC; 00268 } 00269 00270 CTR_CRYPT( dst, src, use_len ); 00271 00272 if( mode == CCM_DECRYPT ) 00273 { 00274 memset( b, 0, 16 ); 00275 memcpy( b, dst, use_len ); 00276 UPDATE_CBC_MAC; 00277 } 00278 00279 dst += use_len; 00280 src += use_len; 00281 len_left -= use_len; 00282 00283 /* 00284 * Increment counter. 00285 * No need to check for overflow thanks to the length check above. 00286 */ 00287 for( i = 0; i < q; i++ ) 00288 if( ++ctr[15-i] != 0 ) 00289 break; 00290 } 00291 00292 /* 00293 * Authentication: reset counter and crypt/mask internal tag 00294 */ 00295 for( i = 0; i < q; i++ ) 00296 ctr[15-i] = 0; 00297 00298 CTR_CRYPT( y, y, 16 ); 00299 memcpy( tag, y, tag_len ); 00300 00301 return( 0 ); 00302 } 00303 00304 /* 00305 * Authenticated encryption 00306 */ 00307 int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length, 00308 const unsigned char *iv, size_t iv_len, 00309 const unsigned char *add, size_t add_len, 00310 const unsigned char *input, unsigned char *output, 00311 unsigned char *tag, size_t tag_len ) 00312 { 00313 return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len, 00314 add, add_len, input, output, tag, tag_len ) ); 00315 } 00316 00317 /* 00318 * Authenticated decryption 00319 */ 00320 int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length, 00321 const unsigned char *iv, size_t iv_len, 00322 const unsigned char *add, size_t add_len, 00323 const unsigned char *input, unsigned char *output, 00324 const unsigned char *tag, size_t tag_len ) 00325 { 00326 int ret; 00327 unsigned char check_tag[16]; 00328 unsigned char i; 00329 int diff; 00330 00331 if( ( ret = ccm_auth_crypt( ctx, CCM_DECRYPT, length, 00332 iv, iv_len, add, add_len, 00333 input, output, check_tag, tag_len ) ) != 0 ) 00334 { 00335 return( ret ); 00336 } 00337 00338 /* Check tag in "constant-time" */ 00339 for( diff = 0, i = 0; i < tag_len; i++ ) 00340 diff |= tag[i] ^ check_tag[i]; 00341 00342 if( diff != 0 ) 00343 { 00344 mbedtls_zeroize( output, length ); 00345 return( MBEDTLS_ERR_CCM_AUTH_FAILED ); 00346 } 00347 00348 return( 0 ); 00349 } 00350 00351 00352 #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) 00353 /* 00354 * Examples 1 to 3 from SP800-38C Appendix C 00355 */ 00356 00357 #define NB_TESTS 3 00358 00359 /* 00360 * The data is the same for all tests, only the used length changes 00361 */ 00362 static const unsigned char key[] = { 00363 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 00364 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f 00365 }; 00366 00367 static const unsigned char iv[] = { 00368 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 00369 0x18, 0x19, 0x1a, 0x1b 00370 }; 00371 00372 static const unsigned char ad[] = { 00373 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 00374 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 00375 0x10, 0x11, 0x12, 0x13 00376 }; 00377 00378 static const unsigned char msg[] = { 00379 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 00380 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 00381 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 00382 }; 00383 00384 static const size_t iv_len [NB_TESTS] = { 7, 8, 12 }; 00385 static const size_t add_len[NB_TESTS] = { 8, 16, 20 }; 00386 static const size_t msg_len[NB_TESTS] = { 4, 16, 24 }; 00387 static const size_t tag_len[NB_TESTS] = { 4, 6, 8 }; 00388 00389 static const unsigned char res[NB_TESTS][32] = { 00390 { 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d }, 00391 { 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62, 00392 0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d, 00393 0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd }, 00394 { 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a, 00395 0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b, 00396 0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5, 00397 0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 } 00398 }; 00399 00400 int mbedtls_ccm_self_test( int verbose ) 00401 { 00402 mbedtls_ccm_context ctx; 00403 unsigned char out[32]; 00404 size_t i; 00405 int ret; 00406 00407 mbedtls_ccm_init( &ctx ); 00408 00409 if( mbedtls_ccm_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 ) 00410 { 00411 if( verbose != 0 ) 00412 mbedtls_printf( " CCM: setup failed" ); 00413 00414 return( 1 ); 00415 } 00416 00417 for( i = 0; i < NB_TESTS; i++ ) 00418 { 00419 if( verbose != 0 ) 00420 mbedtls_printf( " CCM-AES #%u: ", (unsigned int) i + 1 ); 00421 00422 ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i], 00423 iv, iv_len[i], ad, add_len[i], 00424 msg, out, 00425 out + msg_len[i], tag_len[i] ); 00426 00427 if( ret != 0 || 00428 memcmp( out, res[i], msg_len[i] + tag_len[i] ) != 0 ) 00429 { 00430 if( verbose != 0 ) 00431 mbedtls_printf( "failed\n" ); 00432 00433 return( 1 ); 00434 } 00435 00436 ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i], 00437 iv, iv_len[i], ad, add_len[i], 00438 res[i], out, 00439 res[i] + msg_len[i], tag_len[i] ); 00440 00441 if( ret != 0 || 00442 memcmp( out, msg, msg_len[i] ) != 0 ) 00443 { 00444 if( verbose != 0 ) 00445 mbedtls_printf( "failed\n" ); 00446 00447 return( 1 ); 00448 } 00449 00450 if( verbose != 0 ) 00451 mbedtls_printf( "passed\n" ); 00452 } 00453 00454 mbedtls_ccm_free( &ctx ); 00455 00456 if( verbose != 0 ) 00457 mbedtls_printf( "\n" ); 00458 00459 return( 0 ); 00460 } 00461 00462 #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ 00463 00464 #endif /* MBEDTLS_CCM_C */
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