mbed TLS Build
Dependents: Encrypt_Decrypt1 mbed_blink_tls encrypt encrypt
Diff: library/ccm.c
- Revision:
- 0:cdf462088d13
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/library/ccm.c Thu Jan 05 00:18:44 2017 +0000 @@ -0,0 +1,464 @@ +/* + * 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 <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 = (unsigned char*)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 */