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mbedtls/library/ctr_drbg.c
Gilles Peskine e9a3454e09 CTR_DRBG: grab a nonce from the entropy source if needed 
Change the default entropy nonce length to be nonzero in some cases.
Specifically, the default nonce length is now set in such a way that
the entropy input during the initial seeding always contains enough
entropy to achieve the maximum possible security strength per
NIST SP 800-90A given the key size and entropy length.

If MBEDTLS_CTR_DRBG_ENTROPY_LEN is kept to its default value,
mbedtls_ctr_drbg_seed() now grabs extra entropy for a nonce if
MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is disabled and either
MBEDTLS_ENTROPY_FORCE_SHA256 is enabled or MBEDTLS_SHA512_C is
disabled. If MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is enabled, or if
the entropy module uses SHA-512, then the default value of
MBEDTLS_CTR_DRBG_ENTROPY_LEN does not require a second call to the
entropy function to achieve the maximum security strength.

This choice of default nonce size guarantees NIST compliance with the
maximum security strength while keeping backward compatibility and
performance high: in configurations that do not require grabbing more
entropy, the code will not grab more entropy than before.
2019-10-23 19:46:57 +02:00

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/*
* 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 publication.
*
* 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 "mbedtls/platform_util.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 */
/*
* CTR_DRBG context initialization
*/
void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );
/* Indicate that the entropy nonce length is not set explicitly.
* See mbedtls_ctr_drbg_set_nonce_len(). */
ctx->reseed_counter = -1;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &ctx->mutex );
#endif
}
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_platform_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;
}
int mbedtls_ctr_drbg_set_nonce_len( mbedtls_ctr_drbg_context *ctx,
size_t len )
{
/* If mbedtls_ctr_drbg_seed() has already been called, it's
* too late. Return the error code that's closest to making sense. */
if( ctx->f_entropy != NULL )
return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );
if( len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
#if SIZE_MAX > INT_MAX
/* This shouldn't be an issue because
* MBEDTLS_CTR_DRBG_MAX_SEED_INPUT < INT_MAX in any sensible
* configuration, but make sure anyway. */
if( len > INT_MAX )
return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
#endif
/* For backward compatibility with Mbed TLS <= 2.19, store the
* entropy nonce length in a field that already exists, but isn't
* used until after the initial seeding. */
/* Due to the capping of len above, the value fits in an int. */
ctx->reseed_counter = (int) len;
return( 0 );
}
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 ret = 0;
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;
if( ( ret = mbedtls_aes_setkey_enc( &aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
goto exit;
}
/*
* 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;
if( ( ret = mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT,
chain, chain ) ) != 0 )
{
goto exit;
}
}
memcpy( tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE );
/*
* Update IV
*/
buf[3]++;
}
/*
* Do final encryption with reduced data
*/
if( ( ret = mbedtls_aes_setkey_enc( &aes_ctx, tmp,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
goto exit;
}
iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE;
p = output;
for( j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE )
{
if( ( ret = mbedtls_aes_crypt_ecb( &aes_ctx, MBEDTLS_AES_ENCRYPT,
iv, iv ) ) != 0 )
{
goto exit;
}
memcpy( p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE );
p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
}
exit:
mbedtls_aes_free( &aes_ctx );
/*
* tidy up the stack
*/
mbedtls_platform_zeroize( buf, sizeof( buf ) );
mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
mbedtls_platform_zeroize( key, sizeof( key ) );
mbedtls_platform_zeroize( chain, sizeof( chain ) );
if( 0 != ret )
{
/*
* wipe partial seed from memory
*/
mbedtls_platform_zeroize( output, MBEDTLS_CTR_DRBG_SEEDLEN );
}
return( ret );
}
/* CTR_DRBG_Update (SP 800-90A &sect;10.2.1.2)
* ctr_drbg_update_internal(ctx, provided_data)
* implements
* CTR_DRBG_Update(provided_data, Key, V)
* with inputs and outputs
* ctx->aes_ctx = Key
* ctx->counter = V
*/
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;
int ret = 0;
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
*/
if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT,
ctx->counter, p ) ) != 0 )
{
goto exit;
}
p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
}
for( i = 0; i < MBEDTLS_CTR_DRBG_SEEDLEN; i++ )
tmp[i] ^= data[i];
/*
* Update key and counter
*/
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, tmp,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
goto exit;
}
memcpy( ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE,
MBEDTLS_CTR_DRBG_BLOCKSIZE );
exit:
mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
return( ret );
}
/* CTR_DRBG_Instantiate with derivation function (SP 800-90A &sect;10.2.1.3.2)
* mbedtls_ctr_drbg_update(ctx, additional, add_len)
* implements
* CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
* security_strength) -> initial_working_state
* with inputs
* ctx->counter = all-bits-0
* ctx->aes_ctx = context from all-bits-0 key
* additional[:add_len] = entropy_input || nonce || personalization_string
* and with outputs
* ctx = initial_working_state
*/
int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
int ret;
if( add_len == 0 )
return( 0 );
if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )
goto exit;
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
goto exit;
exit:
mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
return( ret );
}
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
/* 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;
(void) mbedtls_ctr_drbg_update_ret( ctx, additional, add_len );
}
#endif /* MBEDTLS_DEPRECATED_REMOVED */
/* CTR_DRBG_Reseed with derivation function (SP 800-90A &sect;10.2.1.4.2)
* mbedtls_ctr_drbg_reseed(ctx, additional, len, nonce_len)
* implements
* CTR_DRBG_Reseed(working_state, entropy_input, additional_input)
* -> new_working_state
* with inputs
* ctx contains working_state
* additional[:len] = additional_input
* and entropy_input comes from calling ctx->f_entropy
* for (ctx->entropy_len + nonce_len) bytes
* and with output
* ctx contains new_working_state
*/
static int mbedtls_ctr_drbg_reseed_internal( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t len,
size_t nonce_len )
{
unsigned char seed[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT];
size_t seedlen = 0;
int ret;
if( ctx->entropy_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
if( nonce_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT - ctx->entropy_len )
return( MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
if( len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT - ctx->entropy_len - nonce_len )
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;
/* Gather entropy for a nonce if requested. */
if( nonce_len != 0 )
{
if( 0 != ctx->f_entropy( ctx->p_entropy, seed, nonce_len ) )
{
return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );
}
seedlen += nonce_len;
}
/* Add additional data if provided. */
if( additional != NULL && len != 0 )
{
memcpy( seed + seedlen, additional, len );
seedlen += len;
}
/* Reduce to 384 bits. */
if( ( ret = block_cipher_df( seed, seed, seedlen ) ) != 0 )
goto exit;
/* Update state. */
if( ( ret = ctr_drbg_update_internal( ctx, seed ) ) != 0 )
goto exit;
ctx->reseed_counter = 1;
exit:
mbedtls_platform_zeroize( seed, sizeof( seed ) );
return( ret );
}
int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional, size_t len )
{
return( mbedtls_ctr_drbg_reseed_internal( ctx, additional, len, 0 ) );
}
/* Return a "good" nonce length for CTR_DRBG. The chosen nonce length
* is sufficient to achieve the maximum security strength given the key
* size and entropy length. If there is enough entropy in the initial
* call to the entropy function to serve as both the entropy input and
* the nonce, don't make a second call to get a nonce. */
static size_t good_nonce_len( size_t entropy_len )
{
if( entropy_len >= MBEDTLS_CTR_DRBG_KEYSIZE * 3 / 2 )
return( 0 );
else
return( ( entropy_len + 1 ) / 2 );
}
/* CTR_DRBG_Instantiate with derivation function (SP 800-90A &sect;10.2.1.3.2)
* mbedtls_ctr_drbg_seed(ctx, f_entropy, p_entropy, custom, len)
* implements
* CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
* security_strength) -> initial_working_state
* with inputs
* custom[:len] = nonce || personalization_string
* where entropy_input comes from f_entropy for ctx->entropy_len bytes
* and with outputs
* ctx = initial_working_state
*/
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 )
{
int ret;
unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
size_t nonce_len;
memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
mbedtls_aes_init( &ctx->aes_ctx );
ctx->f_entropy = f_entropy;
ctx->p_entropy = p_entropy;
if( ctx->entropy_len == 0 )
ctx->entropy_len = MBEDTLS_CTR_DRBG_ENTROPY_LEN;
/* ctx->reseed_counter contains the desired amount of entropy to
* grab for a nonce (see mbedtls_ctr_drbg_set_nonce_len()).
* If it's -1, indicating that the entropy nonce length was not set
* explicitly, use a sufficiently large nonce for security. */
nonce_len = ( ctx->reseed_counter >= 0 ?
(size_t) ctx->reseed_counter :
good_nonce_len( ctx->entropy_len ) );
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
/* Initialize with an empty key. */
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
return( ret );
}
/* Do the initial seeding. */
if( ( ret = mbedtls_ctr_drbg_reseed_internal( ctx, custom, len,
nonce_len ) ) != 0 )
{
return( ret );
}
return( 0 );
}
/* CTR_DRBG_Generate with derivation function (SP 800-90A &sect;10.2.1.5.2)
* mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, additional, add_len)
* implements
* CTR_DRBG_Reseed(working_state, entropy_input, additional[:add_len])
* -> working_state_after_reseed
* if required, then
* CTR_DRBG_Generate(working_state_after_reseed,
* requested_number_of_bits, additional_input)
* -> status, returned_bits, new_working_state
* with inputs
* ctx contains working_state
* requested_number_of_bits = 8 * output_len
* additional[:add_len] = additional_input
* and entropy_input comes from calling ctx->f_entropy
* and with outputs
* status = SUCCESS (this function does the reseed internally)
* returned_bits = output[:output_len]
* ctx contains new_working_state
*/
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 )
{
if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )
goto exit;
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
goto exit;
}
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
*/
if( ( ret = mbedtls_aes_crypt_ecb( &ctx->aes_ctx, MBEDTLS_AES_ENCRYPT,
ctx->counter, tmp ) ) != 0 )
{
goto exit;
}
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;
}
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
goto exit;
ctx->reseed_counter++;
exit:
mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
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;
}
else
{
ret = 0;
}
exit:
mbedtls_platform_zeroize( buf, sizeof( buf ) );
fclose( f );
return( ret );
}
int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx,
const char *path )
{
int ret = 0;
FILE *f = NULL;
size_t n;
unsigned char buf[ MBEDTLS_CTR_DRBG_MAX_INPUT ];
unsigned char c;
if( ( f = fopen( path, "rb" ) ) == NULL )
return( MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR );
n = fread( buf, 1, sizeof( buf ), f );
if( fread( &c, 1, 1, f ) != 0 )
{
ret = MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG;
goto exit;
}
if( n == 0 || ferror( f ) )
{
ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
goto exit;
}
fclose( f );
f = NULL;
ret = mbedtls_ctr_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_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;
mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );
mbedtls_ctr_drbg_set_nonce_len( &ctx, 0 );
CHK( mbedtls_ctr_drbg_seed( &ctx,
ctr_drbg_self_test_entropy,
(void *) entropy_source_pr,
nonce_pers_pr, 16 ) );
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;
mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );
mbedtls_ctr_drbg_set_nonce_len( &ctx, 0 );
CHK( mbedtls_ctr_drbg_seed( &ctx,
ctr_drbg_self_test_entropy,
(void *) entropy_source_nopr,
nonce_pers_nopr, 16 ) );
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 */
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