mbedtls/library/psa_crypto_ecp.c

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/*
* PSA ECP 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_ecp.h"
#include "psa_crypto_random_impl.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/ecp.h>
#include <mbedtls/error.h>
#if ( defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
( defined(PSA_CRYPTO_DRIVER_TEST) && \
defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR) ) )
#define BUILTIN_KEY_TYPE_ECC_KEY_PAIR 1
#endif
#if ( defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) || \
( defined(PSA_CRYPTO_DRIVER_TEST) && \
defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_PUBLIC_KEY) ) )
#define BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY 1
#endif
#if defined(BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
defined(BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH) || \
defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA)
psa_status_t mbedtls_psa_ecp_load_representation(
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psa_key_type_t type, size_t curve_bits,
const uint8_t *data, size_t data_length,
mbedtls_ecp_keypair **p_ecp )
{
mbedtls_ecp_group_id grp_id = MBEDTLS_ECP_DP_NONE;
psa_status_t status;
mbedtls_ecp_keypair *ecp = NULL;
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size_t curve_bytes = data_length;
int explicit_bits = ( curve_bits != 0 );
if( PSA_KEY_TYPE_IS_PUBLIC_KEY( type ) &&
PSA_KEY_TYPE_ECC_GET_FAMILY( type ) != PSA_ECC_FAMILY_MONTGOMERY )
{
/* A Weierstrass public key is represented as:
* - The byte 0x04;
* - `x_P` as a `ceiling(m/8)`-byte string, big-endian;
* - `y_P` as a `ceiling(m/8)`-byte string, big-endian.
* So its data length is 2m+1 where m is the curve size in bits.
*/
if( ( data_length & 1 ) == 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
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curve_bytes = data_length / 2;
/* Montgomery public keys are represented in compressed format, meaning
* their curve_bytes is equal to the amount of input. */
/* Private keys are represented in uncompressed private random integer
* format, meaning their curve_bytes is equal to the amount of input. */
}
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if( explicit_bits )
{
/* With an explicit bit-size, the data must have the matching length. */
if( curve_bytes != PSA_BITS_TO_BYTES( curve_bits ) )
return( PSA_ERROR_INVALID_ARGUMENT );
}
else
{
/* We need to infer the bit-size from the data. Since the only
* information we have is the length in bytes, the value of curve_bits
* at this stage is rounded up to the nearest multiple of 8. */
curve_bits = PSA_BYTES_TO_BITS( curve_bytes );
}
/* Allocate and initialize a key representation. */
ecp = mbedtls_calloc( 1, sizeof( mbedtls_ecp_keypair ) );
if( ecp == NULL )
return( PSA_ERROR_INSUFFICIENT_MEMORY );
mbedtls_ecp_keypair_init( ecp );
/* Load the group. */
grp_id = mbedtls_ecc_group_of_psa( PSA_KEY_TYPE_ECC_GET_FAMILY( type ),
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curve_bits, !explicit_bits );
if( grp_id == MBEDTLS_ECP_DP_NONE )
{
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/* We can't distinguish between a nonsensical family/size combination
* (which would warrant PSA_ERROR_INVALID_ARGUMENT) and a
* well-regarded curve that Mbed TLS just doesn't know about (which
* would warrant PSA_ERROR_NOT_SUPPORTED). For uniformity with how
* curves that Mbed TLS knows about but for which support is disabled
* at build time, return NOT_SUPPORTED. */
status = PSA_ERROR_NOT_SUPPORTED;
goto exit;
}
status = mbedtls_to_psa_error(
mbedtls_ecp_group_load( &ecp->grp, grp_id ) );
if( status != PSA_SUCCESS )
goto exit;
/* Load the key material. */
if( PSA_KEY_TYPE_IS_PUBLIC_KEY( type ) )
{
/* Load the public value. */
status = mbedtls_to_psa_error(
mbedtls_ecp_point_read_binary( &ecp->grp, &ecp->Q,
data,
data_length ) );
if( status != PSA_SUCCESS )
goto exit;
/* Check that the point is on the curve. */
status = mbedtls_to_psa_error(
mbedtls_ecp_check_pubkey( &ecp->grp, &ecp->Q ) );
if( status != PSA_SUCCESS )
goto exit;
}
else
{
/* Load and validate the secret value. */
status = mbedtls_to_psa_error(
mbedtls_ecp_read_key( ecp->grp.id,
ecp,
data,
data_length ) );
if( status != PSA_SUCCESS )
goto exit;
}
*p_ecp = ecp;
exit:
if( status != PSA_SUCCESS )
{
mbedtls_ecp_keypair_free( ecp );
mbedtls_free( ecp );
}
return( status );
}
#endif /* defined(BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
* defined(BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH) ||
* defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) */
#if defined(BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
defined(BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY)
static psa_status_t ecp_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_ecp_keypair *ecp = NULL;
/* Parse input */
status = mbedtls_psa_ecp_load_representation( attributes->core.type,
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attributes->core.bits,
data,
data_length,
&ecp );
if( status != PSA_SUCCESS )
goto exit;
if( PSA_KEY_TYPE_ECC_GET_FAMILY( attributes->core.type ) ==
PSA_ECC_FAMILY_MONTGOMERY )
*bits = ecp->grp.nbits + 1;
else
*bits = ecp->grp.nbits;
/* Re-export the data to PSA export format. There is currently no support
* for other input formats then the export format, so this is a 1-1
* copy operation. */
status = mbedtls_psa_ecp_export_key( attributes->core.type,
ecp,
key_buffer,
key_buffer_size,
key_buffer_length );
exit:
/* Always free the PK object (will also free contained ECP context) */
mbedtls_ecp_keypair_free( ecp );
mbedtls_free( ecp );
return( status );
}
psa_status_t mbedtls_psa_ecp_export_key( psa_key_type_t type,
mbedtls_ecp_keypair *ecp,
uint8_t *data,
size_t data_size,
size_t *data_length )
{
psa_status_t status;
if( PSA_KEY_TYPE_IS_PUBLIC_KEY( type ) )
{
/* Check whether the public part is loaded */
if( mbedtls_ecp_is_zero( &ecp->Q ) )
{
/* Calculate the public key */
status = mbedtls_to_psa_error(
mbedtls_ecp_mul( &ecp->grp, &ecp->Q, &ecp->d, &ecp->grp.G,
mbedtls_psa_get_random,
MBEDTLS_PSA_RANDOM_STATE ) );
if( status != PSA_SUCCESS )
return( status );
}
status = mbedtls_to_psa_error(
mbedtls_ecp_point_write_binary( &ecp->grp, &ecp->Q,
MBEDTLS_ECP_PF_UNCOMPRESSED,
data_length,
data,
data_size ) );
if( status != PSA_SUCCESS )
memset( data, 0, data_size );
return( status );
}
else
{
if( data_size < PSA_BITS_TO_BYTES( ecp->grp.nbits ) )
return( PSA_ERROR_BUFFER_TOO_SMALL );
status = mbedtls_to_psa_error(
mbedtls_ecp_write_key( ecp,
data,
PSA_BITS_TO_BYTES( ecp->grp.nbits ) ) );
if( status == PSA_SUCCESS )
*data_length = PSA_BITS_TO_BYTES( ecp->grp.nbits );
else
memset( data, 0, data_size );
return( status );
}
}
static psa_status_t ecp_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_ecp_keypair *ecp = NULL;
status = mbedtls_psa_ecp_load_representation(
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attributes->core.type, attributes->core.bits,
key_buffer, key_buffer_size, &ecp );
if( status != PSA_SUCCESS )
return( status );
status = mbedtls_psa_ecp_export_key(
PSA_KEY_TYPE_ECC_PUBLIC_KEY(
PSA_KEY_TYPE_ECC_GET_FAMILY( attributes->core.type ) ),
ecp, data, data_size, data_length );
mbedtls_ecp_keypair_free( ecp );
mbedtls_free( ecp );
return( status );
}
#endif /* defined(BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
* defined(BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY)
psa_status_t mbedtls_psa_ecp_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 )
{
return( ecp_import_key( attributes, data, data_length,
key_buffer, key_buffer_size,
key_buffer_length, bits ) );
}
psa_status_t mbedtls_psa_ecp_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 )
{
return( ecp_export_public_key( attributes, key_buffer, key_buffer_size,
data, data_size, data_length ) );
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) */
/*
* BEYOND THIS POINT, TEST DRIVER ENTRY POINTS ONLY.
*/
#if defined(PSA_CRYPTO_DRIVER_TEST)
#if defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR) || \
defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_PUBLIC_KEY)
psa_status_t mbedtls_transparent_test_driver_ecp_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 )
{
return( ecp_import_key( attributes, data, data_length,
key_buffer, key_buffer_size,
key_buffer_length, bits ) );
}
psa_status_t mbedtls_transparent_test_driver_ecp_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 )
{
return( ecp_export_public_key( attributes, key_buffer, key_buffer_size,
data, data_size, data_length ) );
}
#endif /* defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR) ||
defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_PUBLIC_KEY) */
#endif /* PSA_CRYPTO_DRIVER_TEST */
#endif /* MBEDTLS_PSA_CRYPTO_C */