mbed TLS Build
Dependents: Encrypt_Decrypt1 mbed_blink_tls encrypt encrypt
Diff: library/ctr_drbg.c
- Revision:
- 0:cdf462088d13
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/library/ctr_drbg.c Thu Jan 05 00:18:44 2017 +0000 @@ -0,0 +1,593 @@ +/* + * CTR_DRBG implementation based on AES-256 (NIST SP 800-90) + * + * 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) + */ +/* + * The NIST SP 800-90 DRBGs are described in the following publucation. + * + * http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf + */ + +#if !defined(MBEDTLS_CONFIG_FILE) +#include "mbedtls/config.h" +#else +#include MBEDTLS_CONFIG_FILE +#endif + +#if defined(MBEDTLS_CTR_DRBG_C) + +#include "mbedtls/ctr_drbg.h" + +#include <string.h> + +#if defined(MBEDTLS_FS_IO) +#include <stdio.h> +#endif + +#if defined(MBEDTLS_SELF_TEST) +#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 */ + +/* 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; +} + +/* + * CTR_DRBG context initialization + */ +void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx ) +{ + memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) ); + +#if defined(MBEDTLS_THREADING_C) + mbedtls_mutex_init( &ctx->mutex ); +#endif +} + +/* + * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow + * NIST tests to succeed (which require known length fixed entropy) + */ +int mbedtls_ctr_drbg_seed_entropy_len( + mbedtls_ctr_drbg_context *ctx, + int (*f_entropy)(void *, unsigned char *, size_t), + void *p_entropy, + const unsigned char *custom, + size_t len, + size_t entropy_len ) +{ + int ret; + unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE]; + + memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE ); + + mbedtls_aes_init( &ctx->aes_ctx ); + + ctx->f_entropy = f_entropy; + ctx->p_entropy = p_entropy; + + ctx->entropy_len = entropy_len; + ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL; + + /* + * Initialize with an empty key + */ + mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ); + + if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 ) + return( ret ); + + return( 0 ); +} + +int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx, + int (*f_entropy)(void *, unsigned char *, size_t), + void *p_entropy, + const unsigned char *custom, + size_t len ) +{ + return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len, + MBEDTLS_CTR_DRBG_ENTROPY_LEN ) ); +} + +void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx ) +{ + if( ctx == NULL ) + return; + +#if defined(MBEDTLS_THREADING_C) + mbedtls_mutex_free( &ctx->mutex ); +#endif + mbedtls_aes_free( &ctx->aes_ctx ); + mbedtls_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) ); +} + +void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance ) +{ + ctx->prediction_resistance = resistance; +} + +void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx, size_t len ) +{ + ctx->entropy_len = len; +} + +void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx, int interval ) +{ + ctx->reseed_interval = interval; +} + +static int block_cipher_df( unsigned char *output, + const unsigned char *data, size_t data_len ) +{ + unsigned char buf[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16]; + unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN]; + unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE]; + unsigned char chain[MBEDTLS_CTR_DRBG_BLOCKSIZE]; + unsigned char *p, *iv; + mbedtls_aes_context aes_ctx; + + int i, j; + size_t buf_len, use_len; + + if( data_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ) + return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG ); + + memset( buf, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16 ); + mbedtls_aes_init( &aes_ctx ); + + /* + * Construct IV (16 bytes) and S in buffer + * IV = Counter (in 32-bits) padded to 16 with zeroes + * S = Length input string (in 32-bits) || Length of output (in 32-bits) || + * data || 0x80 + * (Total is padded to a multiple of 16-bytes with zeroes) + */ + p = buf + MBEDTLS_CTR_DRBG_BLOCKSIZE; + *p++ = ( data_len >> 24 ) & 0xff; + *p++ = ( data_len >> 16 ) & 0xff; + *p++ = ( data_len >> 8 ) & 0xff; + *p++ = ( data_len ) & 0xff; + p += 3; + *p++ = MBEDTLS_CTR_DRBG_SEEDLEN; + memcpy( p, data, data_len ); + p[data_len] = 0x80; + + buf_len = MBEDTLS_CTR_DRBG_BLOCKSIZE + 8 + data_len + 1; + + for( i = 0; i < MBEDTLS_CTR_DRBG_KEYSIZE; i++ ) + key[i] = i; + + mbedtls_aes_setkey_enc( &aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ); + + /* + * Reduce data to MBEDTLS_CTR_DRBG_SEEDLEN bytes of data + */ + for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE ) + { + p = buf; + memset( chain, 0, MBEDTLS_CTR_DRBG_BLOCKSIZE ); + use_len = buf_len; + + while( use_len > 0 ) + { + for( i = 0; i < MBEDTLS_CTR_DRBG_BLOCKSIZE; i++ ) + chain[i] ^= p[i]; + p += MBEDTLS_CTR_DRBG_BLOCKSIZE; + use_len -= ( use_len >= MBEDTLS_CTR_DRBG_BLOCKSIZE ) ? + MBEDTLS_CTR_DRBG_BLOCKSIZE : use_len; + + mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, chain, chain ); + } + + memcpy( tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE ); + + /* + * Update IV + */ + buf[3]++; + } + + /* + * Do final encryption with reduced data + */ + mbedtls_aes_setkey_enc( &aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS ); + iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE; + p = output; + + for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE ) + { + mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT, iv, iv ); + memcpy( p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE ); + p += MBEDTLS_CTR_DRBG_BLOCKSIZE; + } + + mbedtls_aes_free( &aes_ctx ); + + return( 0 ); +} + +static int ctr_drbg_update_internal( mbedtls_ctr_drbg_context *ctx, + const unsigned char data[MBEDTLS_CTR_DRBG_SEEDLEN] ) +{ + unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN]; + unsigned char *p = tmp; + int i, j; + + memset( tmp, 0, MBEDTLS_CTR_DRBG_SEEDLEN ); + + for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE ) + { + /* + * Increase counter + */ + for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- ) + if( ++ctx->counter[i - 1] != 0 ) + break; + + /* + * Crypt counter block + */ + mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, p ); + + p += MBEDTLS_CTR_DRBG_BLOCKSIZE; + } + + for( i = 0; i < MBEDTLS_CTR_DRBG_SEEDLEN; i++ ) + tmp[i] ^= data[i]; + + /* + * Update key and counter + */ + mbedtls_aes_setkey_enc( &ctx->aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS ); + memcpy( ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE, MBEDTLS_CTR_DRBG_BLOCKSIZE ); + + return( 0 ); +} + +void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx, + const unsigned char *additional, size_t add_len ) +{ + unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN]; + + if( add_len > 0 ) + { + /* MAX_INPUT would be more logical here, but we have to match + * block_cipher_df()'s limits since we can't propagate errors */ + if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ) + add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT; + + block_cipher_df( add_input, additional, add_len ); + ctr_drbg_update_internal( ctx, add_input ); + } +} + +int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx, + const unsigned char *additional, size_t len ) +{ + unsigned char seed[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT]; + size_t seedlen = 0; + + if( ctx->entropy_len + len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ) + return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG ); + + memset( seed, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ); + + /* + * Gather entropy_len bytes of entropy to seed state + */ + if( 0 != ctx->f_entropy( ctx->p_entropy, seed, + ctx->entropy_len ) ) + { + return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED ); + } + + seedlen += ctx->entropy_len; + + /* + * Add additional data + */ + if( additional && len ) + { + memcpy( seed + seedlen, additional, len ); + seedlen += len; + } + + /* + * Reduce to 384 bits + */ + block_cipher_df( seed, seed, seedlen ); + + /* + * Update state + */ + ctr_drbg_update_internal( ctx, seed ); + ctx->reseed_counter = 1; + + return( 0 ); +} + +int mbedtls_ctr_drbg_random_with_add( void *p_rng, + unsigned char *output, size_t output_len, + const unsigned char *additional, size_t add_len ) +{ + int ret = 0; + mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng; + unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN]; + unsigned char *p = output; + unsigned char tmp[MBEDTLS_CTR_DRBG_BLOCKSIZE]; + int i; + size_t use_len; + + if( output_len > MBEDTLS_CTR_DRBG_MAX_REQUEST ) + return( MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG ); + + if( add_len > MBEDTLS_CTR_DRBG_MAX_INPUT ) + return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG ); + + memset( add_input, 0, MBEDTLS_CTR_DRBG_SEEDLEN ); + + if( ctx->reseed_counter > ctx->reseed_interval || + ctx->prediction_resistance ) + { + if( ( ret = mbedtls_ctr_drbg_reseed( ctx, additional, add_len ) ) != 0 ) + return( ret ); + + add_len = 0; + } + + if( add_len > 0 ) + { + block_cipher_df( add_input, additional, add_len ); + ctr_drbg_update_internal( ctx, add_input ); + } + + while( output_len > 0 ) + { + /* + * Increase counter + */ + for( i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i-- ) + if( ++ctx->counter[i - 1] != 0 ) + break; + + /* + * Crypt counter block + */ + mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, tmp ); + + use_len = ( output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE ) ? MBEDTLS_CTR_DRBG_BLOCKSIZE : + output_len; + /* + * Copy random block to destination + */ + memcpy( p, tmp, use_len ); + p += use_len; + output_len -= use_len; + } + + ctr_drbg_update_internal( ctx, add_input ); + + ctx->reseed_counter++; + + return( 0 ); +} + +int mbedtls_ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len ) +{ + int ret; + mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *) p_rng; + +#if defined(MBEDTLS_THREADING_C) + if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) + return( ret ); +#endif + + ret = mbedtls_ctr_drbg_random_with_add( ctx, output, output_len, NULL, 0 ); + +#if defined(MBEDTLS_THREADING_C) + if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) + return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); +#endif + + return( ret ); +} + +#if defined(MBEDTLS_FS_IO) +int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path ) +{ + int ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR; + FILE *f; + unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ]; + + if( ( f = fopen( path, "wb" ) ) == NULL ) + return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR ); + + if( ( ret = mbedtls_ctr_drbg_random( ctx, buf, MBEDTLS_CTR_DRBG_MAX_INPUT ) ) != 0 ) + goto exit; + + if( fwrite( buf, 1, MBEDTLS_CTR_DRBG_MAX_INPUT, f ) != MBEDTLS_CTR_DRBG_MAX_INPUT ) + { + ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR; + goto exit; + } + + ret = 0; + +exit: + fclose( f ); + return( ret ); +} + +int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path ) +{ + FILE *f; + size_t n; + unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ]; + + if( ( f = fopen( path, "rb" ) ) == NULL ) + return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR ); + + fseek( f, 0, SEEK_END ); + n = (size_t) ftell( f ); + fseek( f, 0, SEEK_SET ); + + if( n > MBEDTLS_CTR_DRBG_MAX_INPUT ) + { + fclose( f ); + return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG ); + } + + if( fread( buf, 1, n, f ) != n ) + { + fclose( f ); + return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR ); + } + + fclose( f ); + + mbedtls_ctr_drbg_update( ctx, buf, n ); + + return( mbedtls_ctr_drbg_write_seed_file( ctx, path ) ); +} +#endif /* MBEDTLS_FS_IO */ + +#if defined(MBEDTLS_SELF_TEST) + +static const unsigned char entropy_source_pr[96] = + { 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16, + 0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02, + 0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b, + 0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb, + 0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9, + 0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95, + 0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63, + 0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3, + 0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31, + 0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4, + 0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56, + 0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68 }; + +static const unsigned char entropy_source_nopr[64] = + { 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14, + 0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe, + 0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d, + 0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20, + 0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9, + 0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46, + 0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e, + 0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e }; + +static const unsigned char nonce_pers_pr[16] = + { 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2, + 0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c }; + +static const unsigned char nonce_pers_nopr[16] = + { 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5, + 0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f }; + +static const unsigned char result_pr[16] = + { 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f, + 0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23 }; + +static const unsigned char result_nopr[16] = + { 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88, + 0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f }; + +static size_t test_offset; +static int ctr_drbg_self_test_entropy( void *data, unsigned char *buf, + size_t len ) +{ + const unsigned char *p = data; + memcpy( buf, p + test_offset, len ); + test_offset += len; + return( 0 ); +} + +#define CHK( c ) if( (c) != 0 ) \ + { \ + if( verbose != 0 ) \ + mbedtls_printf( "failed\n" ); \ + return( 1 ); \ + } + +/* + * Checkup routine + */ +int mbedtls_ctr_drbg_self_test( int verbose ) +{ + mbedtls_ctr_drbg_context ctx; + unsigned char buf[16]; + + mbedtls_ctr_drbg_init( &ctx ); + + /* + * Based on a NIST CTR_DRBG test vector (PR = True) + */ + if( verbose != 0 ) + mbedtls_printf( " CTR_DRBG (PR = TRUE) : " ); + + test_offset = 0; + CHK( mbedtls_ctr_drbg_seed_entropy_len( &ctx, ctr_drbg_self_test_entropy, + (void *) entropy_source_pr, nonce_pers_pr, 16, 32 ) ); + mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON ); + CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) ); + CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) ); + CHK( memcmp( buf, result_pr, MBEDTLS_CTR_DRBG_BLOCKSIZE ) ); + + mbedtls_ctr_drbg_free( &ctx ); + + if( verbose != 0 ) + mbedtls_printf( "passed\n" ); + + /* + * Based on a NIST CTR_DRBG test vector (PR = FALSE) + */ + if( verbose != 0 ) + mbedtls_printf( " CTR_DRBG (PR = FALSE): " ); + + mbedtls_ctr_drbg_init( &ctx ); + + test_offset = 0; + CHK( mbedtls_ctr_drbg_seed_entropy_len( &ctx, ctr_drbg_self_test_entropy, + (void *) entropy_source_nopr, nonce_pers_nopr, 16, 32 ) ); + CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) ); + CHK( mbedtls_ctr_drbg_reseed( &ctx, NULL, 0 ) ); + CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) ); + CHK( memcmp( buf, result_nopr, 16 ) ); + + mbedtls_ctr_drbg_free( &ctx ); + + if( verbose != 0 ) + mbedtls_printf( "passed\n" ); + + if( verbose != 0 ) + mbedtls_printf( "\n" ); + + return( 0 ); +} +#endif /* MBEDTLS_SELF_TEST */ + +#endif /* MBEDTLS_CTR_DRBG_C */