/*
* PSA RSA layer on top of Mbed TLS crypto
*/
/*
* Copyright The Mbed TLS Contributors
* 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.
*/
#include "common.h"
#if defined(MBEDTLS_PSA_CRYPTO_C)
#include <psa/crypto.h>
#include "psa_crypto_core.h"
#include "psa_crypto_random_impl.h"
#include "psa_crypto_rsa.h"
#include "psa_crypto_hash.h"
#include <stdlib.h>
#include <string.h>
#include "mbedtls/platform.h"
#if !defined(MBEDTLS_PLATFORM_C)
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#include <mbedtls/rsa.h>
#include <mbedtls/error.h>
#include <mbedtls/pk.h>
#include <mbedtls/pk_internal.h>
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
/* Mbed TLS doesn't support non-byte-aligned key sizes (i.e. key sizes
* that are not a multiple of 8) well. For example, there is only
* mbedtls_rsa_get_len(), which returns a number of bytes, and no
* way to return the exact bit size of a key.
* To keep things simple, reject non-byte-aligned key sizes. */
static psa_status_t psa_check_rsa_key_byte_aligned(
const mbedtls_rsa_context *rsa )
{
mbedtls_mpi n;
psa_status_t status;
mbedtls_mpi_init( &n );
status = mbedtls_to_psa_error(
mbedtls_rsa_export( rsa, &n, NULL, NULL, NULL, NULL ) );
if( status == PSA_SUCCESS )
{
if( mbedtls_mpi_bitlen( &n ) % 8 != 0 )
status = PSA_ERROR_NOT_SUPPORTED;
}
mbedtls_mpi_free( &n );
return( status );
}
psa_status_t mbedtls_psa_rsa_load_representation(
psa_key_type_t type, const uint8_t *data, size_t data_length,
mbedtls_rsa_context **p_rsa )
{
psa_status_t status;
mbedtls_pk_context ctx;
size_t bits;
mbedtls_pk_init( &ctx );
/* Parse the data. */
if( PSA_KEY_TYPE_IS_KEY_PAIR( type ) )
status = mbedtls_to_psa_error(
mbedtls_pk_parse_key( &ctx, data, data_length, NULL, 0 ) );
else
status = mbedtls_to_psa_error(
mbedtls_pk_parse_public_key( &ctx, data, data_length ) );
if( status != PSA_SUCCESS )
goto exit;
/* We have something that the pkparse module recognizes. If it is a
* valid RSA key, store it. */
if( mbedtls_pk_get_type( &ctx ) != MBEDTLS_PK_RSA )
{
status = PSA_ERROR_INVALID_ARGUMENT;
goto exit;
}
/* The size of an RSA key doesn't have to be a multiple of 8. Mbed TLS
* supports non-byte-aligned key sizes, but not well. For example,
* mbedtls_rsa_get_len() returns the key size in bytes, not in bits. */
bits = PSA_BYTES_TO_BITS( mbedtls_rsa_get_len( mbedtls_pk_rsa( ctx ) ) );
if( bits > PSA_VENDOR_RSA_MAX_KEY_BITS )
{
status = PSA_ERROR_NOT_SUPPORTED;
goto exit;
}
status = psa_check_rsa_key_byte_aligned( mbedtls_pk_rsa( ctx ) );
if( status != PSA_SUCCESS )
goto exit;
/* Copy out the pointer to the RSA context, and reset the PK context
* such that pk_free doesn't free the RSA context we just grabbed. */
*p_rsa = mbedtls_pk_rsa( ctx );
ctx.pk_info = NULL;
exit:
mbedtls_pk_free( &ctx );
return( status );
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) ||
* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
psa_status_t mbedtls_psa_rsa_import_key(
const psa_key_attributes_t *attributes,
const uint8_t *data, size_t data_length,
uint8_t *key_buffer, size_t key_buffer_size,
size_t *key_buffer_length, size_t *bits )
{
psa_status_t status;
mbedtls_rsa_context *rsa = NULL;
/* Parse input */
status = mbedtls_psa_rsa_load_representation( attributes->core.type,
data,
data_length,
&rsa );
if( status != PSA_SUCCESS )
goto exit;
*bits = (psa_key_bits_t) PSA_BYTES_TO_BITS( mbedtls_rsa_get_len( rsa ) );
/* Re-export the data to PSA export format, such that we can store export
* representation in the key slot. Export representation in case of RSA is
* the smallest representation that's allowed as input, so a straight-up
* allocation of the same size as the input buffer will be large enough. */
status = mbedtls_psa_rsa_export_key( attributes->core.type,
rsa,
key_buffer,
key_buffer_size,
key_buffer_length );
exit:
/* Always free the RSA object */
mbedtls_rsa_free( rsa );
mbedtls_free( rsa );
return( status );
}
psa_status_t mbedtls_psa_rsa_export_key( psa_key_type_t type,
mbedtls_rsa_context *rsa,
uint8_t *data,
size_t data_size,
size_t *data_length )
{
#if defined(MBEDTLS_PK_WRITE_C)
int ret;
mbedtls_pk_context pk;
uint8_t *pos = data + data_size;
mbedtls_pk_init( &pk );
pk.pk_info = &mbedtls_rsa_info;
pk.pk_ctx = rsa;
/* PSA Crypto API defines the format of an RSA key as a DER-encoded
* representation of the non-encrypted PKCS#1 RSAPrivateKey for a
* private key and of the RFC3279 RSAPublicKey for a public key. */
if( PSA_KEY_TYPE_IS_KEY_PAIR( type ) )
ret = mbedtls_pk_write_key_der( &pk, data, data_size );
else
ret = mbedtls_pk_write_pubkey( &pos, data, &pk );
if( ret < 0 )
{
/* Clean up in case pk_write failed halfway through. */
memset( data, 0, data_size );
return( mbedtls_to_psa_error( ret ) );
}
/* The mbedtls_pk_xxx functions write to the end of the buffer.
* Move the data to the beginning and erase remaining data
* at the original location. */
if( 2 * (size_t) ret <= data_size )
{
memcpy( data, data + data_size - ret, ret );
memset( data + data_size - ret, 0, ret );
}
else if( (size_t) ret < data_size )
{
memmove( data, data + data_size - ret, ret );
memset( data + ret, 0, data_size - ret );
}
*data_length = ret;
return( PSA_SUCCESS );
#else
(void) type;
(void) rsa;
(void) data;
(void) data_size;
(void) data_length;
return( PSA_ERROR_NOT_SUPPORTED );
#endif /* MBEDTLS_PK_WRITE_C */
}
psa_status_t mbedtls_psa_rsa_export_public_key(
const psa_key_attributes_t *attributes,
const uint8_t *key_buffer, size_t key_buffer_size,
uint8_t *data, size_t data_size, size_t *data_length )
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_rsa_context *rsa = NULL;
status = mbedtls_psa_rsa_load_representation(
attributes->core.type, key_buffer, key_buffer_size, &rsa );
if( status != PSA_SUCCESS )
return( status );
status = mbedtls_psa_rsa_export_key( PSA_KEY_TYPE_RSA_PUBLIC_KEY,
rsa,
data,
data_size,
data_length );
mbedtls_rsa_free( rsa );
mbedtls_free( rsa );
return( status );
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) && \
defined(MBEDTLS_GENPRIME)
static psa_status_t psa_rsa_read_exponent( const uint8_t *domain_parameters,
size_t domain_parameters_size,
int *exponent )
{
size_t i;
uint32_t acc = 0;
if( domain_parameters_size == 0 )
{
*exponent = 65537;
return( PSA_SUCCESS );
}
/* Mbed TLS encodes the public exponent as an int. For simplicity, only
* support values that fit in a 32-bit integer, which is larger than
* int on just about every platform anyway. */
if( domain_parameters_size > sizeof( acc ) )
return( PSA_ERROR_NOT_SUPPORTED );
for( i = 0; i < domain_parameters_size; i++ )
acc = ( acc << 8 ) | domain_parameters[i];
if( acc > INT_MAX )
return( PSA_ERROR_NOT_SUPPORTED );
*exponent = acc;
return( PSA_SUCCESS );
}
psa_status_t mbedtls_psa_rsa_generate_key(
const psa_key_attributes_t *attributes,
uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length )
{
psa_status_t status;
mbedtls_rsa_context rsa;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
int exponent;
status = psa_rsa_read_exponent( attributes->domain_parameters,
attributes->domain_parameters_size,
&exponent );
if( status != PSA_SUCCESS )
return( status );
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, MBEDTLS_MD_NONE );
ret = mbedtls_rsa_gen_key( &rsa,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE,
(unsigned int)attributes->core.bits,
exponent );
if( ret != 0 )
return( mbedtls_to_psa_error( ret ) );
status = mbedtls_psa_rsa_export_key( attributes->core.type,
&rsa, key_buffer, key_buffer_size,
key_buffer_length );
mbedtls_rsa_free( &rsa );
return( status );
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR)
* defined(MBEDTLS_GENPRIME) */
/****************************************************************/
/* Sign/verify hashes */
/****************************************************************/
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
/* Decode the hash algorithm from alg and store the mbedtls encoding in
* md_alg. Verify that the hash length is acceptable. */
static psa_status_t psa_rsa_decode_md_type( psa_algorithm_t alg,
size_t hash_length,
mbedtls_md_type_t *md_alg )
{
psa_algorithm_t hash_alg = PSA_ALG_SIGN_GET_HASH( alg );
const mbedtls_md_info_t *md_info = mbedtls_md_info_from_psa( hash_alg );
*md_alg = mbedtls_md_get_type( md_info );
/* The Mbed TLS RSA module uses an unsigned int for hash length
* parameters. Validate that it fits so that we don't risk an
* overflow later. */
#if SIZE_MAX > UINT_MAX
if( hash_length > UINT_MAX )
return( PSA_ERROR_INVALID_ARGUMENT );
#endif
/* For signatures using a hash, the hash length must be correct. */
if( alg != PSA_ALG_RSA_PKCS1V15_SIGN_RAW )
{
if( md_info == NULL )
return( PSA_ERROR_NOT_SUPPORTED );
if( mbedtls_md_get_size( md_info ) != hash_length )
return( PSA_ERROR_INVALID_ARGUMENT );
}
return( PSA_SUCCESS );
}
psa_status_t mbedtls_psa_rsa_sign_hash(
const psa_key_attributes_t *attributes,
const uint8_t *key_buffer, size_t key_buffer_size,
psa_algorithm_t alg, const uint8_t *hash, size_t hash_length,
uint8_t *signature, size_t signature_size, size_t *signature_length )
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_rsa_context *rsa = NULL;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_md_type_t md_alg;
status = mbedtls_psa_rsa_load_representation( attributes->core.type,
key_buffer,
key_buffer_size,
&rsa );
if( status != PSA_SUCCESS )
return( status );
status = psa_rsa_decode_md_type( alg, hash_length, &md_alg );
if( status != PSA_SUCCESS )
goto exit;
if( signature_size < mbedtls_rsa_get_len( rsa ) )
{
status = PSA_ERROR_BUFFER_TOO_SMALL;
goto exit;
}
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN)
if( PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) )
{
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V15,
MBEDTLS_MD_NONE );
ret = mbedtls_rsa_pkcs1_sign( rsa,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
md_alg,
(unsigned int) hash_length,
hash,
signature );
}
else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
if( PSA_ALG_IS_RSA_PSS( alg ) )
{
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V21, md_alg );
ret = mbedtls_rsa_rsassa_pss_sign( rsa,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PRIVATE,
MBEDTLS_MD_NONE,
(unsigned int) hash_length,
hash,
signature );
}
else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS */
{
status = PSA_ERROR_INVALID_ARGUMENT;
goto exit;
}
if( ret == 0 )
*signature_length = mbedtls_rsa_get_len( rsa );
status = mbedtls_to_psa_error( ret );
exit:
mbedtls_rsa_free( rsa );
mbedtls_free( rsa );
return( status );
}
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
static int rsa_pss_expected_salt_len( psa_algorithm_t alg,
const mbedtls_rsa_context *rsa,
size_t hash_length )
{
if( PSA_ALG_IS_RSA_PSS_ANY_SALT( alg ) )
return( MBEDTLS_RSA_SALT_LEN_ANY );
/* Otherwise: standard salt length, i.e. largest possible salt length
* up to the hash length. */
int klen = (int) mbedtls_rsa_get_len( rsa ); // known to fit
int hlen = (int) hash_length; // known to fit
int room = klen - 2 - hlen;
if( room < 0 )
return( 0 ); // there is no valid signature in this case anyway
else if( room > hlen )
return( hlen );
else
return( room );
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS */
psa_status_t mbedtls_psa_rsa_verify_hash(
const psa_key_attributes_t *attributes,
const uint8_t *key_buffer, size_t key_buffer_size,
psa_algorithm_t alg, const uint8_t *hash, size_t hash_length,
const uint8_t *signature, size_t signature_length )
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_rsa_context *rsa = NULL;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_md_type_t md_alg;
status = mbedtls_psa_rsa_load_representation( attributes->core.type,
key_buffer,
key_buffer_size,
&rsa );
if( status != PSA_SUCCESS )
goto exit;
status = psa_rsa_decode_md_type( alg, hash_length, &md_alg );
if( status != PSA_SUCCESS )
goto exit;
if( signature_length != mbedtls_rsa_get_len( rsa ) )
{
status = PSA_ERROR_INVALID_SIGNATURE;
goto exit;
}
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN)
if( PSA_ALG_IS_RSA_PKCS1V15_SIGN( alg ) )
{
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V15,
MBEDTLS_MD_NONE );
ret = mbedtls_rsa_pkcs1_verify( rsa,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
md_alg,
(unsigned int) hash_length,
hash,
signature );
}
else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
if( PSA_ALG_IS_RSA_PSS( alg ) )
{
int slen = rsa_pss_expected_salt_len( alg, rsa, hash_length );
mbedtls_rsa_set_padding( rsa, MBEDTLS_RSA_PKCS_V21, md_alg );
ret = mbedtls_rsa_rsassa_pss_verify_ext( rsa,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE,
MBEDTLS_RSA_PUBLIC,
md_alg,
(unsigned int) hash_length,
hash,
md_alg,
slen,
signature );
}
else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS */
{
status = PSA_ERROR_INVALID_ARGUMENT;
goto exit;
}
/* Mbed TLS distinguishes "invalid padding" from "valid padding but
* the rest of the signature is invalid". This has little use in
* practice and PSA doesn't report this distinction. */
status = ( ret == MBEDTLS_ERR_RSA_INVALID_PADDING ) ?
PSA_ERROR_INVALID_SIGNATURE :
mbedtls_to_psa_error( ret );
exit:
mbedtls_rsa_free( rsa );
mbedtls_free( rsa );
return( status );
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) */
#endif /* MBEDTLS_PSA_CRYPTO_C */