2fa6b5f503
Attempting to create an ECC key with a curve specification that is not
valid can plausibly fail with PSA_ERROR_INVALID_ARGUMENT ("this is not
a curve specification at all") or PSA_ERROR_NOT_SUPPORTED ("this may
be a curve specification, but not one I support"). The choice of error
is somewhat subjective.
Before this commit, due to happenstance in the implementation, an
attempt to use a curve that is declared in the PSA API but not
implemented in Mbed TLS returned PSA_ERROR_INVALID_ARGUMENT, whereas
an attempt to use a curve that Mbed TLS supports but for which support
was disabled at compile-time returned PSA_ERROR_NOT_SUPPORTED. This
inconsistency made it difficult to write negative tests that could
work whether the curve is implemented via Mbed TLS code or via a
driver.
After this commit, any attempt to use parameters that are not
recognized fails with NOT_SUPPORTED, whether a curve with the
specified size might plausibly exist or not, because "might plausibly
exist" is not something Mbed TLS can determine.
To keep returning INVALID_ARGUMENT when importing an ECC key with an
explicit "bits" attribute that is inconsistent with the size of the
key material, this commit changes the way mbedtls_ecc_group_of_psa()
works: it now works on a size in bits rather than bytes, with an extra
flag indicating whether the bit-size must be exact or not.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
136 lines
5.8 KiB
C
136 lines
5.8 KiB
C
/*
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* PSA ECP layer on top of Mbed TLS crypto
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef PSA_CRYPTO_ECP_H
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#define PSA_CRYPTO_ECP_H
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#include <psa/crypto.h>
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#include <mbedtls/ecp.h>
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/** Load the contents of a key buffer into an internal ECP representation
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*
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* \param[in] type The type of key contained in \p data.
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* \param[in] data The buffer from which to load the representation.
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* \param[in] data_length The size in bytes of \p data.
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* \param[out] p_ecp Returns a pointer to an ECP context on success.
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* The caller is responsible for freeing both the
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* contents of the context and the context itself
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* when done.
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*/
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psa_status_t mbedtls_psa_ecp_load_representation( psa_key_type_t type,
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size_t curve_bits,
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const uint8_t *data,
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size_t data_length,
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mbedtls_ecp_keypair **p_ecp );
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/** Import an ECP key in binary format.
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*
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* \note The signature of this function is that of a PSA driver
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* import_key entry point. This function behaves as an import_key
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* entry point as defined in the PSA driver interface specification for
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* transparent drivers.
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*
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* \param[in] attributes The attributes for the key to import.
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* \param[in] data The buffer containing the key data in import
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* format.
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* \param[in] data_length Size of the \p data buffer in bytes.
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* \param[out] key_buffer The buffer containing the key data in output
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* format.
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* \param[in] key_buffer_size Size of the \p key_buffer buffer in bytes. This
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* size is greater or equal to \p data_length.
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* \param[out] key_buffer_length The length of the data written in \p
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* key_buffer in bytes.
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* \param[out] bits The key size in number of bits.
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*
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* \retval #PSA_SUCCESS The ECP key was imported successfully.
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* \retval #PSA_ERROR_INVALID_ARGUMENT
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* The key data is not correctly formatted.
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* \retval #PSA_ERROR_NOT_SUPPORTED
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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* \retval #PSA_ERROR_CORRUPTION_DETECTED
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*/
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psa_status_t mbedtls_psa_ecp_import_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *data, size_t data_length,
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uint8_t *key_buffer, size_t key_buffer_size,
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size_t *key_buffer_length, size_t *bits );
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/** Export an ECP key to export representation
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*
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* \param[in] type The type of key (public/private) to export
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* \param[in] ecp The internal ECP representation from which to export
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* \param[out] data The buffer to export to
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* \param[in] data_size The length of the buffer to export to
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* \param[out] data_length The amount of bytes written to \p data
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*/
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psa_status_t mbedtls_psa_ecp_export_key( psa_key_type_t type,
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mbedtls_ecp_keypair *ecp,
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uint8_t *data,
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size_t data_size,
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size_t *data_length );
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/** Export an ECP public key or the public part of an ECP key pair in binary
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* format.
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*
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* \note The signature of this function is that of a PSA driver
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* export_public_key entry point. This function behaves as an
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* export_public_key entry point as defined in the PSA driver interface
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* specification.
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*
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* \param[in] attributes The attributes for the key to export.
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* \param[in] key_buffer Material or context of the key to export.
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* \param[in] key_buffer_size Size of the \p key_buffer buffer in bytes.
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* \param[out] data Buffer where the key data is to be written.
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* \param[in] data_size Size of the \p data buffer in bytes.
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* \param[out] data_length On success, the number of bytes written in
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* \p data
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*
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* \retval #PSA_SUCCESS The ECP public key was exported successfully.
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* \retval #PSA_ERROR_NOT_SUPPORTED
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* \retval #PSA_ERROR_COMMUNICATION_FAILURE
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* \retval #PSA_ERROR_HARDWARE_FAILURE
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* \retval #PSA_ERROR_CORRUPTION_DETECTED
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* \retval #PSA_ERROR_STORAGE_FAILURE
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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*/
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psa_status_t mbedtls_psa_ecp_export_public_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *key_buffer, size_t key_buffer_size,
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uint8_t *data, size_t data_size, size_t *data_length );
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/*
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* BEYOND THIS POINT, TEST DRIVER ENTRY POINTS ONLY.
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*/
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#if defined(PSA_CRYPTO_DRIVER_TEST)
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psa_status_t mbedtls_transparent_test_driver_ecp_import_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *data, size_t data_length,
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uint8_t *key_buffer, size_t key_buffer_size,
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size_t *key_buffer_length, size_t *bits );
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psa_status_t mbedtls_transparent_test_driver_ecp_export_public_key(
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const psa_key_attributes_t *attributes,
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const uint8_t *key_buffer, size_t key_buffer_size,
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uint8_t *data, size_t data_size, size_t *data_length );
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#endif /* PSA_CRYPTO_DRIVER_TEST */
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#endif /* PSA_CRYPTO_ECP_H */
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