/* * HMAC_DRBG implementation (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 800-90A DRBGs are described in the following publication. * http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf * References below are based on rev. 1 (January 2012). */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_HMAC_DRBG_C) #include "mbedtls/hmac_drbg.h" #include "mbedtls/platform_util.h" #include #if defined(MBEDTLS_FS_IO) #include #endif #if defined(MBEDTLS_SELF_TEST) #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_printf printf #endif /* MBEDTLS_SELF_TEST */ #endif /* MBEDTLS_PLATFORM_C */ /* * HMAC_DRBG context initialization */ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx ) { memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_init( &ctx->mutex ); #endif } /* * HMAC_DRBG update, using optional additional data (10.1.2.2) */ int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len ) { size_t md_len = mbedtls_md_get_size( ctx->md_ctx.md_info ); unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1; unsigned char sep[1]; unsigned char K[MBEDTLS_MD_MAX_SIZE]; int ret = MBEDTLS_ERR_MD_BAD_INPUT_DATA; for( sep[0] = 0; sep[0] < rounds; sep[0]++ ) { /* Step 1 or 4 */ if( ( ret = mbedtls_md_hmac_reset( &ctx->md_ctx ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx, sep, 1 ) ) != 0 ) goto exit; if( rounds == 2 ) { if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx, additional, add_len ) ) != 0 ) goto exit; } if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, K ) ) != 0 ) goto exit; /* Step 2 or 5 */ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, K, md_len ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 ) goto exit; } exit: mbedtls_platform_zeroize( K, sizeof( K ) ); return( ret ); } #if !defined(MBEDTLS_DEPRECATED_REMOVED) void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len ) { (void) mbedtls_hmac_drbg_update_ret( ctx, additional, add_len ); } #endif /* MBEDTLS_DEPRECATED_REMOVED */ /* * Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA) */ int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t * md_info, const unsigned char *data, size_t data_len ) { int ret; if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 ) return( ret ); /* * Set initial working state. * Use the V memory location, which is currently all 0, to initialize the * MD context with an all-zero key. Then set V to its initial value. */ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, mbedtls_md_get_size( md_info ) ) ) != 0 ) return( ret ); memset( ctx->V, 0x01, mbedtls_md_get_size( md_info ) ); if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, data, data_len ) ) != 0 ) return( ret ); return( 0 ); } /* * Internal function used both for seeding and reseeding the DRBG. * Comments starting with arabic numbers refer to section 10.1.2.4 * of SP800-90A, while roman numbers refer to section 9.2. */ static int hmac_drbg_reseed_core( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len, int use_nonce ) { unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT]; size_t seedlen = 0; int ret; { size_t total_entropy_len; if( use_nonce == 0 ) total_entropy_len = ctx->entropy_len; else total_entropy_len = ctx->entropy_len * 3 / 2; /* III. Check input length */ if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT || total_entropy_len + len > MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT ) { return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG ); } } memset( seed, 0, MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT ); /* IV. Gather entropy_len bytes of entropy for the seed */ if( ( ret = ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) ) != 0 ) { return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED ); } seedlen += ctx->entropy_len; /* For initial seeding, allow adding of nonce generated * from the entropy source. See Sect 8.6.7 in SP800-90A. */ if( use_nonce ) { /* Note: We don't merge the two calls to f_entropy() in order * to avoid requesting too much entropy from f_entropy() * at once. Specifically, if the underlying digest is not * SHA-1, 3 / 2 * entropy_len is at least 36 Bytes, which * is larger than the maximum of 32 Bytes that our own * entropy source implementation can emit in a single * call in configurations disabling SHA-512. */ if( ( ret = ctx->f_entropy( ctx->p_entropy, seed + seedlen, ctx->entropy_len / 2 ) ) != 0 ) { return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED ); } seedlen += ctx->entropy_len / 2; } /* 1. Concatenate entropy and additional data if any */ if( additional != NULL && len != 0 ) { memcpy( seed + seedlen, additional, len ); seedlen += len; } /* 2. Update state */ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, seed, seedlen ) ) != 0 ) goto exit; /* 3. Reset reseed_counter */ ctx->reseed_counter = 1; exit: /* 4. Done */ mbedtls_platform_zeroize( seed, seedlen ); return( ret ); } /* * HMAC_DRBG reseeding: 10.1.2.4 + 9.2 */ int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, const unsigned char *additional, size_t len ) { return( hmac_drbg_reseed_core( ctx, additional, len, 0 ) ); } /* * HMAC_DRBG initialisation (10.1.2.3 + 9.1) * * The nonce is not passed as a separate parameter but extracted * from the entropy source as suggested in 8.6.7. */ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t * md_info, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len ) { int ret; size_t md_size; if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 ) return( ret ); md_size = mbedtls_md_get_size( md_info ); /* * Set initial working state. * Use the V memory location, which is currently all 0, to initialize the * MD context with an all-zero key. Then set V to its initial value. */ if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, md_size ) ) != 0 ) return( ret ); memset( ctx->V, 0x01, md_size ); ctx->f_entropy = f_entropy; ctx->p_entropy = p_entropy; ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL; if( ctx->entropy_len == 0 ) { /* * See SP800-57 5.6.1 (p. 65-66) for the security strength provided by * each hash function, then according to SP800-90A rev1 10.1 table 2, * min_entropy_len (in bits) is security_strength. * * (This also matches the sizes used in the NIST test vectors.) */ ctx->entropy_len = md_size <= 20 ? 16 : /* 160-bits hash -> 128 bits */ md_size <= 28 ? 24 : /* 224-bits hash -> 192 bits */ 32; /* better (256+) -> 256 bits */ } if( ( ret = hmac_drbg_reseed_core( ctx, custom, len, 1 /* add nonce */ ) ) != 0 ) { return( ret ); } return( 0 ); } /* * Set prediction resistance */ void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx, int resistance ) { ctx->prediction_resistance = resistance; } /* * Set entropy length grabbed for seeding */ void mbedtls_hmac_drbg_set_entropy_len( mbedtls_hmac_drbg_context *ctx, size_t len ) { ctx->entropy_len = len; } /* * Set reseed interval */ void mbedtls_hmac_drbg_set_reseed_interval( mbedtls_hmac_drbg_context *ctx, int interval ) { ctx->reseed_interval = interval; } /* * HMAC_DRBG random function with optional additional data: * 10.1.2.5 (arabic) + 9.3 (Roman) */ int mbedtls_hmac_drbg_random_with_add( void *p_rng, unsigned char *output, size_t out_len, const unsigned char *additional, size_t add_len ) { int ret; mbedtls_hmac_drbg_context *ctx = (mbedtls_hmac_drbg_context *) p_rng; size_t md_len = mbedtls_md_get_size( ctx->md_ctx.md_info ); size_t left = out_len; unsigned char *out = output; /* II. Check request length */ if( out_len > MBEDTLS_HMAC_DRBG_MAX_REQUEST ) return( MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG ); /* III. Check input length */ if( add_len > MBEDTLS_HMAC_DRBG_MAX_INPUT ) return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG ); /* 1. (aka VII and IX) Check reseed counter and PR */ if( ctx->f_entropy != NULL && /* For no-reseeding instances */ ( ctx->prediction_resistance == MBEDTLS_HMAC_DRBG_PR_ON || ctx->reseed_counter > ctx->reseed_interval ) ) { if( ( ret = mbedtls_hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 ) return( ret ); add_len = 0; /* VII.4 */ } /* 2. Use additional data if any */ if( additional != NULL && add_len != 0 ) { if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, additional, add_len ) ) != 0 ) goto exit; } /* 3, 4, 5. Generate bytes */ while( left != 0 ) { size_t use_len = left > md_len ? md_len : left; if( ( ret = mbedtls_md_hmac_reset( &ctx->md_ctx ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len ) ) != 0 ) goto exit; if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 ) goto exit; memcpy( out, ctx->V, use_len ); out += use_len; left -= use_len; } /* 6. Update */ if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, additional, add_len ) ) != 0 ) goto exit; /* 7. Update reseed counter */ ctx->reseed_counter++; exit: /* 8. Done */ return( ret ); } /* * HMAC_DRBG random function */ int mbedtls_hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ) { int ret; mbedtls_hmac_drbg_context *ctx = (mbedtls_hmac_drbg_context *) p_rng; #if defined(MBEDTLS_THREADING_C) if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) return( ret ); #endif ret = mbedtls_hmac_drbg_random_with_add( ctx, output, out_len, NULL, 0 ); #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); #endif return( ret ); } /* * Free an HMAC_DRBG context */ void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx ) { if( ctx == NULL ) return; #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free( &ctx->mutex ); #endif mbedtls_md_free( &ctx->md_ctx ); mbedtls_platform_zeroize( ctx, sizeof( mbedtls_hmac_drbg_context ) ); } #if defined(MBEDTLS_FS_IO) int mbedtls_hmac_drbg_write_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path ) { int ret; FILE *f; unsigned char buf[ MBEDTLS_HMAC_DRBG_MAX_INPUT ]; if( ( f = fopen( path, "wb" ) ) == NULL ) return( MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR ); if( ( ret = mbedtls_hmac_drbg_random( ctx, buf, sizeof( buf ) ) ) != 0 ) goto exit; if( fwrite( buf, 1, sizeof( buf ), f ) != sizeof( buf ) ) { ret = MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR; goto exit; } ret = 0; exit: fclose( f ); mbedtls_platform_zeroize( buf, sizeof( buf ) ); return( ret ); } int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path ) { int ret = 0; FILE *f = NULL; size_t n; unsigned char buf[ MBEDTLS_HMAC_DRBG_MAX_INPUT ]; unsigned char c; if( ( f = fopen( path, "rb" ) ) == NULL ) return( MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR ); n = fread( buf, 1, sizeof( buf ), f ); if( fread( &c, 1, 1, f ) != 0 ) { ret = MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG; goto exit; } if( n == 0 || ferror( f ) ) { ret = MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR; goto exit; } fclose( f ); f = NULL; ret = mbedtls_hmac_drbg_update_ret( ctx, buf, n ); exit: mbedtls_platform_zeroize( buf, sizeof( buf ) ); if( f != NULL ) fclose( f ); if( ret != 0 ) return( ret ); return( mbedtls_hmac_drbg_write_seed_file( ctx, path ) ); } #endif /* MBEDTLS_FS_IO */ #if defined(MBEDTLS_SELF_TEST) #if !defined(MBEDTLS_SHA1_C) /* Dummy checkup routine */ int mbedtls_hmac_drbg_self_test( int verbose ) { (void) verbose; return( 0 ); } #else #define OUTPUT_LEN 80 /* From a NIST PR=true test vector */ static const unsigned char entropy_pr[] = { 0xa0, 0xc9, 0xab, 0x58, 0xf1, 0xe2, 0xe5, 0xa4, 0xde, 0x3e, 0xbd, 0x4f, 0xf7, 0x3e, 0x9c, 0x5b, 0x64, 0xef, 0xd8, 0xca, 0x02, 0x8c, 0xf8, 0x11, 0x48, 0xa5, 0x84, 0xfe, 0x69, 0xab, 0x5a, 0xee, 0x42, 0xaa, 0x4d, 0x42, 0x17, 0x60, 0x99, 0xd4, 0x5e, 0x13, 0x97, 0xdc, 0x40, 0x4d, 0x86, 0xa3, 0x7b, 0xf5, 0x59, 0x54, 0x75, 0x69, 0x51, 0xe4 }; static const unsigned char result_pr[OUTPUT_LEN] = { 0x9a, 0x00, 0xa2, 0xd0, 0x0e, 0xd5, 0x9b, 0xfe, 0x31, 0xec, 0xb1, 0x39, 0x9b, 0x60, 0x81, 0x48, 0xd1, 0x96, 0x9d, 0x25, 0x0d, 0x3c, 0x1e, 0x94, 0x10, 0x10, 0x98, 0x12, 0x93, 0x25, 0xca, 0xb8, 0xfc, 0xcc, 0x2d, 0x54, 0x73, 0x19, 0x70, 0xc0, 0x10, 0x7a, 0xa4, 0x89, 0x25, 0x19, 0x95, 0x5e, 0x4b, 0xc6, 0x00, 0x1d, 0x7f, 0x4e, 0x6a, 0x2b, 0xf8, 0xa3, 0x01, 0xab, 0x46, 0x05, 0x5c, 0x09, 0xa6, 0x71, 0x88, 0xf1, 0xa7, 0x40, 0xee, 0xf3, 0xe1, 0x5c, 0x02, 0x9b, 0x44, 0xaf, 0x03, 0x44 }; /* From a NIST PR=false test vector */ static const unsigned char entropy_nopr[] = { 0x79, 0x34, 0x9b, 0xbf, 0x7c, 0xdd, 0xa5, 0x79, 0x95, 0x57, 0x86, 0x66, 0x21, 0xc9, 0x13, 0x83, 0x11, 0x46, 0x73, 0x3a, 0xbf, 0x8c, 0x35, 0xc8, 0xc7, 0x21, 0x5b, 0x5b, 0x96, 0xc4, 0x8e, 0x9b, 0x33, 0x8c, 0x74, 0xe3, 0xe9, 0x9d, 0xfe, 0xdf }; static const unsigned char result_nopr[OUTPUT_LEN] = { 0xc6, 0xa1, 0x6a, 0xb8, 0xd4, 0x20, 0x70, 0x6f, 0x0f, 0x34, 0xab, 0x7f, 0xec, 0x5a, 0xdc, 0xa9, 0xd8, 0xca, 0x3a, 0x13, 0x3e, 0x15, 0x9c, 0xa6, 0xac, 0x43, 0xc6, 0xf8, 0xa2, 0xbe, 0x22, 0x83, 0x4a, 0x4c, 0x0a, 0x0a, 0xff, 0xb1, 0x0d, 0x71, 0x94, 0xf1, 0xc1, 0xa5, 0xcf, 0x73, 0x22, 0xec, 0x1a, 0xe0, 0x96, 0x4e, 0xd4, 0xbf, 0x12, 0x27, 0x46, 0xe0, 0x87, 0xfd, 0xb5, 0xb3, 0xe9, 0x1b, 0x34, 0x93, 0xd5, 0xbb, 0x98, 0xfa, 0xed, 0x49, 0xe8, 0x5f, 0x13, 0x0f, 0xc8, 0xa4, 0x59, 0xb7 }; /* "Entropy" from buffer */ static size_t test_offset; static int hmac_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 for HMAC_DRBG with SHA-1 */ int mbedtls_hmac_drbg_self_test( int verbose ) { mbedtls_hmac_drbg_context ctx; unsigned char buf[OUTPUT_LEN]; const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ); mbedtls_hmac_drbg_init( &ctx ); /* * PR = True */ if( verbose != 0 ) mbedtls_printf( " HMAC_DRBG (PR = True) : " ); test_offset = 0; CHK( mbedtls_hmac_drbg_seed( &ctx, md_info, hmac_drbg_self_test_entropy, (void *) entropy_pr, NULL, 0 ) ); mbedtls_hmac_drbg_set_prediction_resistance( &ctx, MBEDTLS_HMAC_DRBG_PR_ON ); CHK( mbedtls_hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) ); CHK( mbedtls_hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) ); CHK( memcmp( buf, result_pr, OUTPUT_LEN ) ); mbedtls_hmac_drbg_free( &ctx ); mbedtls_hmac_drbg_free( &ctx ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); /* * PR = False */ if( verbose != 0 ) mbedtls_printf( " HMAC_DRBG (PR = False) : " ); mbedtls_hmac_drbg_init( &ctx ); test_offset = 0; CHK( mbedtls_hmac_drbg_seed( &ctx, md_info, hmac_drbg_self_test_entropy, (void *) entropy_nopr, NULL, 0 ) ); CHK( mbedtls_hmac_drbg_reseed( &ctx, NULL, 0 ) ); CHK( mbedtls_hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) ); CHK( mbedtls_hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) ); CHK( memcmp( buf, result_nopr, OUTPUT_LEN ) ); mbedtls_hmac_drbg_free( &ctx ); mbedtls_hmac_drbg_free( &ctx ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); if( verbose != 0 ) mbedtls_printf( "\n" ); return( 0 ); } #endif /* MBEDTLS_SHA1_C */ #endif /* MBEDTLS_SELF_TEST */ #endif /* MBEDTLS_HMAC_DRBG_C */