| /* |
| * NIST SP800-38C compliant CCM implementation |
| * |
| * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved |
| * |
| * This file is part of mbed TLS (https://tls.mbed.org) |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| */ |
| |
| /* |
| * 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 <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 */ |
| |
| /* Implementation that should never be optimized out by the compiler */ |
| static void mbedtls_zeroize( void *v, size_t n ) { |
| volatile unsigned char *p = v; while( n-- ) *p++ = 0; |
| } |
| |
| #define CCM_ENCRYPT 0 |
| #define CCM_DECRYPT 1 |
| |
| /* |
| * Initialize context |
| */ |
| void mbedtls_ccm_init( mbedtls_ccm_context *ctx ) |
| { |
| 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; |
| |
| 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 ) |
| { |
| mbedtls_cipher_free( &ctx->cipher_ctx ); |
| mbedtls_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 ) \ |
| 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]; |
| |
| /* |
| * 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) |
| */ |
| if( tag_len < 4 || 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_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 ) |
| { |
| return( ccm_auth_crypt( ctx, CCM_ENCRYPT, length, iv, iv_len, |
| add, add_len, input, output, tag, tag_len ) ); |
| } |
| |
| /* |
| * Authenticated decryption |
| */ |
| 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 ) |
| { |
| int ret; |
| unsigned char check_tag[16]; |
| unsigned char i; |
| int diff; |
| |
| 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_zeroize( output, length ); |
| return( MBEDTLS_ERR_CCM_AUTH_FAILED ); |
| } |
| |
| return( 0 ); |
| } |
| |
| |
| #if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C) |
| /* |
| * Examples 1 to 3 from SP800-38C Appendix C |
| */ |
| |
| #define NB_TESTS 3 |
| |
| /* |
| * 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[] = { |
| 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][32] = { |
| { 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; |
| unsigned char out[32]; |
| 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 ); |
| |
| ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i], |
| iv, iv_len[i], ad, add_len[i], |
| msg, out, |
| out + msg_len[i], tag_len[i] ); |
| |
| if( ret != 0 || |
| memcmp( out, res[i], msg_len[i] + tag_len[i] ) != 0 ) |
| { |
| if( verbose != 0 ) |
| mbedtls_printf( "failed\n" ); |
| |
| return( 1 ); |
| } |
| |
| ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i], |
| iv, iv_len[i], ad, add_len[i], |
| res[i], out, |
| res[i] + msg_len[i], tag_len[i] ); |
| |
| if( ret != 0 || |
| memcmp( out, 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 */ |
