620 lines
26 KiB
C
620 lines
26 KiB
C
/**
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* \file psa/crypto_sizes.h
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*
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* \brief PSA cryptography module: Mbed TLS buffer size macros
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*
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* \note This file may not be included directly. Applications must
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* include psa/crypto.h.
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*
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* This file contains the definitions of macros that are useful to
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* compute buffer sizes. The signatures and semantics of these macros
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* are standardized, but the definitions are not, because they depend on
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* the available algorithms and, in some cases, on permitted tolerances
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* on buffer sizes.
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*
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* In implementations with isolation between the application and the
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* cryptography module, implementers should take care to ensure that
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* the definitions that are exposed to applications match what the
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* module implements.
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*
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* Macros that compute sizes whose values do not depend on the
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* implementation are in crypto.h.
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*/
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/*
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* Copyright (C) 2018, ARM Limited, All Rights Reserved
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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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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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#ifndef PSA_CRYPTO_SIZES_H
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#define PSA_CRYPTO_SIZES_H
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/* Include the Mbed TLS configuration file, the way Mbed TLS does it
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* in each of its header files. */
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "../mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#define PSA_BITS_TO_BYTES(bits) (((bits) + 7) / 8)
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#define PSA_BYTES_TO_BITS(bytes) ((bytes) * 8)
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/** The size of the output of psa_hash_finish(), in bytes.
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*
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* This is also the hash size that psa_hash_verify() expects.
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*
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* \param alg A hash algorithm (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_HASH(\p alg) is true), or an HMAC algorithm
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* (#PSA_ALG_HMAC(\c hash_alg) where \c hash_alg is a
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* hash algorithm).
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*
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* \return The hash size for the specified hash algorithm.
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* If the hash algorithm is not recognized, return 0.
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* An implementation may return either 0 or the correct size
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* for a hash algorithm that it recognizes, but does not support.
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*/
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#define PSA_HASH_SIZE(alg) \
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( \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD2 ? 16 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD4 ? 16 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_MD5 ? 16 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_RIPEMD160 ? 20 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_1 ? 20 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_224 ? 28 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_256 ? 32 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_384 ? 48 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512 ? 64 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_224 ? 28 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA_512_256 ? 32 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_224 ? 28 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_256 ? 32 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_384 ? 48 : \
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PSA_ALG_HMAC_GET_HASH(alg) == PSA_ALG_SHA3_512 ? 64 : \
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0)
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/** \def PSA_HASH_MAX_SIZE
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*
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* Maximum size of a hash.
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*
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* This macro must expand to a compile-time constant integer. This value
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* should be the maximum size of a hash supported by the implementation,
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* in bytes, and must be no smaller than this maximum.
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*/
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/* Note: for HMAC-SHA-3, the block size is 144 bytes for HMAC-SHA3-226,
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* 136 bytes for HMAC-SHA3-256, 104 bytes for SHA3-384, 72 bytes for
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* HMAC-SHA3-512. */
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#if defined(MBEDTLS_SHA512_C)
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#define PSA_HASH_MAX_SIZE 64
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#define PSA_HMAC_MAX_HASH_BLOCK_SIZE 128
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#else
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#define PSA_HASH_MAX_SIZE 32
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#define PSA_HMAC_MAX_HASH_BLOCK_SIZE 64
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#endif
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/** \def PSA_MAC_MAX_SIZE
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*
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* Maximum size of a MAC.
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*
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* This macro must expand to a compile-time constant integer. This value
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* should be the maximum size of a MAC supported by the implementation,
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* in bytes, and must be no smaller than this maximum.
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*/
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/* All non-HMAC MACs have a maximum size that's smaller than the
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* minimum possible value of PSA_HASH_MAX_SIZE in this implementation. */
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/* Note that the encoding of truncated MAC algorithms limits this value
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* to 64 bytes.
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*/
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#define PSA_MAC_MAX_SIZE PSA_HASH_MAX_SIZE
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/** The tag size for an AEAD algorithm, in bytes.
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*
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* \param alg An AEAD algorithm
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* (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_AEAD(\p alg) is true).
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*
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* \return The tag size for the specified algorithm.
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* If the AEAD algorithm does not have an identified
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* tag that can be distinguished from the rest of
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* the ciphertext, return 0.
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* If the AEAD algorithm is not recognized, return 0.
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* An implementation may return either 0 or a
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* correct size for an AEAD algorithm that it
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* recognizes, but does not support.
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*/
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#define PSA_AEAD_TAG_LENGTH(alg) \
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(PSA_ALG_IS_AEAD(alg) ? \
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(((alg) & PSA_ALG_AEAD_TAG_LENGTH_MASK) >> PSA_AEAD_TAG_LENGTH_OFFSET) : \
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0)
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/* The maximum size of an RSA key on this implementation, in bits.
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* This is a vendor-specific macro.
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*
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* Mbed TLS does not set a hard limit on the size of RSA keys: any key
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* whose parameters fit in a bignum is accepted. However large keys can
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* induce a large memory usage and long computation times. Unlike other
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* auxiliary macros in this file and in crypto.h, which reflect how the
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* library is configured, this macro defines how the library is
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* configured. This implementation refuses to import or generate an
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* RSA key whose size is larger than the value defined here.
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*
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* Note that an implementation may set different size limits for different
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* operations, and does not need to accept all key sizes up to the limit. */
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#define PSA_VENDOR_RSA_MAX_KEY_BITS 4096
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/* The maximum size of an ECC key on this implementation, in bits.
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* This is a vendor-specific macro. */
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#if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 521
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#elif defined(MBEDTLS_ECP_DP_BP512R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 512
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#elif defined(MBEDTLS_ECP_DP_CURVE448_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 448
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#elif defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 384
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#elif defined(MBEDTLS_ECP_DP_BP384R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 384
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#elif defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 256
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#elif defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 256
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#elif defined(MBEDTLS_ECP_DP_BP256R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 256
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#elif defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 255
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#elif defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 224
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#elif defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 224
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#elif defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 192
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#elif defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED)
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 192
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#else
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#define PSA_VENDOR_ECC_MAX_CURVE_BITS 0
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#endif
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/** \def PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN
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*
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* This macro returns the maximum length of the PSK supported
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* by the TLS-1.2 PSK-to-MS key derivation.
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*
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* Quoting RFC 4279, Sect 5.3:
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* TLS implementations supporting these ciphersuites MUST support
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* arbitrary PSK identities up to 128 octets in length, and arbitrary
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* PSKs up to 64 octets in length. Supporting longer identities and
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* keys is RECOMMENDED.
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*
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* Therefore, no implementation should define a value smaller than 64
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* for #PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN.
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*/
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#define PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN 128
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/** \def PSA_ASYMMETRIC_SIGNATURE_MAX_SIZE
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*
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* Maximum size of an asymmetric signature.
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*
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* This macro must expand to a compile-time constant integer. This value
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* should be the maximum size of a MAC supported by the implementation,
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* in bytes, and must be no smaller than this maximum.
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*/
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#define PSA_ASYMMETRIC_SIGNATURE_MAX_SIZE \
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PSA_BITS_TO_BYTES( \
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PSA_VENDOR_RSA_MAX_KEY_BITS > PSA_VENDOR_ECC_MAX_CURVE_BITS ? \
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PSA_VENDOR_RSA_MAX_KEY_BITS : \
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PSA_VENDOR_ECC_MAX_CURVE_BITS \
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)
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/** The maximum size of a block cipher supported by the implementation. */
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#define PSA_MAX_BLOCK_CIPHER_BLOCK_SIZE 16
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/** The size of the output of psa_mac_sign_finish(), in bytes.
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*
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* This is also the MAC size that psa_mac_verify_finish() expects.
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*
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* \param key_type The type of the MAC key.
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* \param key_bits The size of the MAC key in bits.
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* \param alg A MAC algorithm (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_MAC(\p alg) is true).
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*
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* \return The MAC size for the specified algorithm with
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* the specified key parameters.
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* \return 0 if the MAC algorithm is not recognized.
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* \return Either 0 or the correct size for a MAC algorithm that
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* the implementation recognizes, but does not support.
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* \return Unspecified if the key parameters are not consistent
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* with the algorithm.
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*/
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#define PSA_MAC_FINAL_SIZE(key_type, key_bits, alg) \
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((alg) & PSA_ALG_MAC_TRUNCATION_MASK ? PSA_MAC_TRUNCATED_LENGTH(alg) : \
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PSA_ALG_IS_HMAC(alg) ? PSA_HASH_SIZE(PSA_ALG_HMAC_GET_HASH(alg)) : \
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PSA_ALG_IS_BLOCK_CIPHER_MAC(alg) ? PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) : \
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((void)(key_type), (void)(key_bits), 0))
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/** The maximum size of the output of psa_aead_encrypt(), in bytes.
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*
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* If the size of the ciphertext buffer is at least this large, it is
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* guaranteed that psa_aead_encrypt() will not fail due to an
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* insufficient buffer size. Depending on the algorithm, the actual size of
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* the ciphertext may be smaller.
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*
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* \param alg An AEAD algorithm
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* (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_AEAD(\p alg) is true).
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* \param plaintext_length Size of the plaintext in bytes.
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*
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* \return The AEAD ciphertext size for the specified
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* algorithm.
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* If the AEAD algorithm is not recognized, return 0.
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* An implementation may return either 0 or a
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* correct size for an AEAD algorithm that it
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* recognizes, but does not support.
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*/
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#define PSA_AEAD_ENCRYPT_OUTPUT_SIZE(alg, plaintext_length) \
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(PSA_AEAD_TAG_LENGTH(alg) != 0 ? \
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(plaintext_length) + PSA_AEAD_TAG_LENGTH(alg) : \
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0)
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/** The maximum size of the output of psa_aead_finish(), in bytes.
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*
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* If the size of the ciphertext buffer is at least this large, it is
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* guaranteed that psa_aead_finish() will not fail due to an
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* insufficient buffer size. Depending on the algorithm, the actual size of
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* the ciphertext may be smaller.
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*
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* \param alg An AEAD algorithm
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* (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_AEAD(\p alg) is true).
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*
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* \return The maximum trailing ciphertext size for the
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* specified algorithm.
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* If the AEAD algorithm is not recognized, return 0.
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* An implementation may return either 0 or a
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* correct size for an AEAD algorithm that it
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* recognizes, but does not support.
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*/
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#define PSA_AEAD_FINISH_OUTPUT_SIZE(alg) \
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((size_t)0)
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/** The maximum size of the output of psa_aead_decrypt(), in bytes.
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*
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* If the size of the plaintext buffer is at least this large, it is
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* guaranteed that psa_aead_decrypt() will not fail due to an
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* insufficient buffer size. Depending on the algorithm, the actual size of
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* the plaintext may be smaller.
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*
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* \param alg An AEAD algorithm
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* (\c PSA_ALG_XXX value such that
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* #PSA_ALG_IS_AEAD(\p alg) is true).
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* \param ciphertext_length Size of the plaintext in bytes.
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*
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* \return The AEAD ciphertext size for the specified
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* algorithm.
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* If the AEAD algorithm is not recognized, return 0.
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* An implementation may return either 0 or a
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* correct size for an AEAD algorithm that it
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* recognizes, but does not support.
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*/
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#define PSA_AEAD_DECRYPT_OUTPUT_SIZE(alg, ciphertext_length) \
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(PSA_AEAD_TAG_LENGTH(alg) != 0 ? \
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(plaintext_length) - PSA_AEAD_TAG_LENGTH(alg) : \
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0)
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#define PSA_RSA_MINIMUM_PADDING_SIZE(alg) \
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(PSA_ALG_IS_RSA_OAEP(alg) ? \
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2 * PSA_HASH_FINAL_SIZE(PSA_ALG_RSA_OAEP_GET_HASH(alg)) + 1 : \
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11 /*PKCS#1v1.5*/)
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/**
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* \brief ECDSA signature size for a given curve bit size
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*
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* \param curve_bits Curve size in bits.
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* \return Signature size in bytes.
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*
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* \note This macro returns a compile-time constant if its argument is one.
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*/
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#define PSA_ECDSA_SIGNATURE_SIZE(curve_bits) \
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(PSA_BITS_TO_BYTES(curve_bits) * 2)
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/** Safe signature buffer size for psa_asymmetric_sign().
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*
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* This macro returns a safe buffer size for a signature using a key
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* of the specified type and size, with the specified algorithm.
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* Note that the actual size of the signature may be smaller
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* (some algorithms produce a variable-size signature).
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*
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* \warning This function may call its arguments multiple times or
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* zero times, so you should not pass arguments that contain
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* side effects.
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*
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* \param key_type An asymmetric key type (this may indifferently be a
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* key pair type or a public key type).
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* \param key_bits The size of the key in bits.
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* \param alg The signature algorithm.
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*
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* \return If the parameters are valid and supported, return
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* a buffer size in bytes that guarantees that
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* psa_asymmetric_sign() will not fail with
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* #PSA_ERROR_BUFFER_TOO_SMALL.
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* If the parameters are a valid combination that is not supported
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* by the implementation, this macro either shall return either a
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* sensible size or 0.
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* If the parameters are not valid, the
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* return value is unspecified.
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*/
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#define PSA_ASYMMETRIC_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) \
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(PSA_KEY_TYPE_IS_RSA(key_type) ? ((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \
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PSA_KEY_TYPE_IS_ECC(key_type) ? PSA_ECDSA_SIGNATURE_SIZE(key_bits) : \
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((void)alg, 0))
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/** Safe output buffer size for psa_asymmetric_encrypt().
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*
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* This macro returns a safe buffer size for a ciphertext produced using
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* a key of the specified type and size, with the specified algorithm.
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* Note that the actual size of the ciphertext may be smaller, depending
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* on the algorithm.
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*
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* \warning This function may call its arguments multiple times or
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* zero times, so you should not pass arguments that contain
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* side effects.
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*
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* \param key_type An asymmetric key type (this may indifferently be a
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* key pair type or a public key type).
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* \param key_bits The size of the key in bits.
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* \param alg The signature algorithm.
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*
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* \return If the parameters are valid and supported, return
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* a buffer size in bytes that guarantees that
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* psa_asymmetric_encrypt() will not fail with
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* #PSA_ERROR_BUFFER_TOO_SMALL.
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* If the parameters are a valid combination that is not supported
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* by the implementation, this macro either shall return either a
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* sensible size or 0.
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* If the parameters are not valid, the
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* return value is unspecified.
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*/
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#define PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \
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(PSA_KEY_TYPE_IS_RSA(key_type) ? \
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((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \
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0)
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/** Safe output buffer size for psa_asymmetric_decrypt().
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*
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* This macro returns a safe buffer size for a ciphertext produced using
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* a key of the specified type and size, with the specified algorithm.
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* Note that the actual size of the ciphertext may be smaller, depending
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* on the algorithm.
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*
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* \warning This function may call its arguments multiple times or
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* zero times, so you should not pass arguments that contain
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* side effects.
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*
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* \param key_type An asymmetric key type (this may indifferently be a
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* key pair type or a public key type).
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* \param key_bits The size of the key in bits.
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* \param alg The signature algorithm.
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*
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* \return If the parameters are valid and supported, return
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* a buffer size in bytes that guarantees that
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* psa_asymmetric_decrypt() will not fail with
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* #PSA_ERROR_BUFFER_TOO_SMALL.
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* If the parameters are a valid combination that is not supported
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* by the implementation, this macro either shall return either a
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* sensible size or 0.
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* If the parameters are not valid, the
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* return value is unspecified.
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*/
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#define PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \
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(PSA_KEY_TYPE_IS_RSA(key_type) ? \
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PSA_BITS_TO_BYTES(key_bits) - PSA_RSA_MINIMUM_PADDING_SIZE(alg) : \
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0)
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/* Maximum size of the ASN.1 encoding of an INTEGER with the specified
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* number of bits.
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*
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* This definition assumes that bits <= 2^19 - 9 so that the length field
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* is at most 3 bytes. The length of the encoding is the length of the
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* bit string padded to a whole number of bytes plus:
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* - 1 type byte;
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* - 1 to 3 length bytes;
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* - 0 to 1 bytes of leading 0 due to the sign bit.
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*/
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#define PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(bits) \
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((bits) / 8 + 5)
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/* Maximum size of the export encoding of an RSA public key.
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* Assumes that the public exponent is less than 2^32.
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*
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* SubjectPublicKeyInfo ::= SEQUENCE {
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* algorithm AlgorithmIdentifier,
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* subjectPublicKey BIT STRING } -- contains RSAPublicKey
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* AlgorithmIdentifier ::= SEQUENCE {
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* algorithm OBJECT IDENTIFIER,
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* parameters NULL }
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* RSAPublicKey ::= SEQUENCE {
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* modulus INTEGER, -- n
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* publicExponent INTEGER } -- e
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*
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* - 3 * 4 bytes of SEQUENCE overhead;
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* - 1 + 1 + 9 bytes of algorithm (RSA OID);
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* - 2 bytes of NULL;
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* - 4 bytes of BIT STRING overhead;
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* - n : INTEGER;
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* - 7 bytes for the public exponent.
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*/
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#define PSA_KEY_EXPORT_RSA_PUBLIC_KEY_MAX_SIZE(key_bits) \
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(PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) + 36)
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/* Maximum size of the export encoding of an RSA key pair.
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* Assumes thatthe public exponent is less than 2^32 and that the size
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* difference between the two primes is at most 1 bit.
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*
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* RSAPrivateKey ::= SEQUENCE {
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* version Version, -- 0
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* modulus INTEGER, -- N-bit
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* publicExponent INTEGER, -- 32-bit
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* privateExponent INTEGER, -- N-bit
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* prime1 INTEGER, -- N/2-bit
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* prime2 INTEGER, -- N/2-bit
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* exponent1 INTEGER, -- N/2-bit
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* exponent2 INTEGER, -- N/2-bit
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* coefficient INTEGER, -- N/2-bit
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* }
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*
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* - 4 bytes of SEQUENCE overhead;
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* - 3 bytes of version;
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* - 7 half-size INTEGERs plus 2 full-size INTEGERs,
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* overapproximated as 9 half-size INTEGERS;
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* - 7 bytes for the public exponent.
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*/
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#define PSA_KEY_EXPORT_RSA_KEYPAIR_MAX_SIZE(key_bits) \
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(9 * PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE((key_bits) / 2 + 1) + 14)
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/* Maximum size of the export encoding of a DSA public key.
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*
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* SubjectPublicKeyInfo ::= SEQUENCE {
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* algorithm AlgorithmIdentifier,
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* subjectPublicKey BIT STRING } -- contains DSAPublicKey
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* AlgorithmIdentifier ::= SEQUENCE {
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* algorithm OBJECT IDENTIFIER,
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* parameters Dss-Parms } -- SEQUENCE of 3 INTEGERs
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* DSAPublicKey ::= INTEGER -- public key, Y
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*
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* - 3 * 4 bytes of SEQUENCE overhead;
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* - 1 + 1 + 7 bytes of algorithm (DSA OID);
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* - 4 bytes of BIT STRING overhead;
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* - 3 full-size INTEGERs (p, g, y);
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* - 1 + 1 + 32 bytes for 1 sub-size INTEGER (q <= 256 bits).
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*/
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#define PSA_KEY_EXPORT_DSA_PUBLIC_KEY_MAX_SIZE(key_bits) \
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(PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) * 3 + 59)
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/* Maximum size of the export encoding of a DSA key pair.
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*
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* DSAPrivateKey ::= SEQUENCE {
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* version Version, -- 0
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* prime INTEGER, -- p
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* subprime INTEGER, -- q
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* generator INTEGER, -- g
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* public INTEGER, -- y
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* private INTEGER, -- x
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* }
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*
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* - 4 bytes of SEQUENCE overhead;
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* - 3 bytes of version;
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* - 3 full-size INTEGERs (p, g, y);
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* - 2 * (1 + 1 + 32) bytes for 2 sub-size INTEGERs (q, x <= 256 bits).
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*/
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#define PSA_KEY_EXPORT_DSA_KEYPAIR_MAX_SIZE(key_bits) \
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(PSA_KEY_EXPORT_ASN1_INTEGER_MAX_SIZE(key_bits) * 3 + 75)
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/* Maximum size of the export encoding of an ECC public key.
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*
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* SubjectPublicKeyInfo ::= SEQUENCE {
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* algorithm AlgorithmIdentifier,
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* subjectPublicKey BIT STRING } -- contains ECPoint
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* AlgorithmIdentifier ::= SEQUENCE {
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* algorithm OBJECT IDENTIFIER,
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* parameters OBJECT IDENTIFIER } -- namedCurve
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* ECPoint ::= ...
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* -- first 8 bits: 0x04;
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* -- then x_P as a `ceiling(m/8)`-byte string, big endian;
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* -- then y_P as a `ceiling(m/8)`-byte string, big endian;
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* -- where `m` is the bit size associated with the curve.
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*
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* - 2 * 4 bytes of SEQUENCE overhead;
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* - 1 + 1 + 7 bytes of algorithm (id-ecPublicKey OID);
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* - 1 + 1 + 12 bytes of namedCurve OID;
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* - 4 bytes of BIT STRING overhead;
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* - 1 byte + 2 * point size in ECPoint.
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*/
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#define PSA_KEY_EXPORT_ECC_PUBLIC_KEY_MAX_SIZE(key_bits) \
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(2 * PSA_BITS_TO_BYTES(key_bits) + 36)
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/* Maximum size of the export encoding of an ECC key pair.
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*
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* An ECC key pair is represented by the secret value.
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*/
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#define PSA_KEY_EXPORT_ECC_KEYPAIR_MAX_SIZE(key_bits) \
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(PSA_BITS_TO_BYTES(key_bits))
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/** Safe output buffer size for psa_export_key() or psa_export_public_key().
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*
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* This macro returns a compile-time constant if its arguments are
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* compile-time constants.
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*
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* \warning This function may call its arguments multiple times or
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* zero times, so you should not pass arguments that contain
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* side effects.
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*
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* The following code illustrates how to allocate enough memory to export
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* a key by querying the key type and size at runtime.
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* \code{c}
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* psa_key_type_t key_type;
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* size_t key_bits;
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* psa_status_t status;
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* status = psa_get_key_information(key, &key_type, &key_bits);
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* if (status != PSA_SUCCESS) handle_error(...);
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* size_t buffer_size = PSA_KEY_EXPORT_MAX_SIZE(key_type, key_bits);
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* unsigned char *buffer = malloc(buffer_size);
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* if (buffer != NULL) handle_error(...);
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* size_t buffer_length;
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* status = psa_export_key(key, buffer, buffer_size, &buffer_length);
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* if (status != PSA_SUCCESS) handle_error(...);
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* \endcode
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|
*
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|
* For psa_export_public_key(), calculate the buffer size from the
|
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* public key type. You can use the macro #PSA_KEY_TYPE_PUBLIC_KEY_OF_KEYPAIR
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* to convert a key pair type to the corresponding public key type.
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* \code{c}
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|
* psa_key_type_t key_type;
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|
* size_t key_bits;
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|
* psa_status_t status;
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* status = psa_get_key_information(key, &key_type, &key_bits);
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* if (status != PSA_SUCCESS) handle_error(...);
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|
* psa_key_type_t public_key_type = PSA_KEY_TYPE_PUBLIC_KEY_OF_KEYPAIR(key_type);
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|
* size_t buffer_size = PSA_KEY_EXPORT_MAX_SIZE(public_key_type, key_bits);
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|
* unsigned char *buffer = malloc(buffer_size);
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|
* if (buffer != NULL) handle_error(...);
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|
* size_t buffer_length;
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|
* status = psa_export_public_key(key, buffer, buffer_size, &buffer_length);
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|
* if (status != PSA_SUCCESS) handle_error(...);
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|
* \endcode
|
|
*
|
|
* \param key_type A supported key type.
|
|
* \param key_bits The size of the key in bits.
|
|
*
|
|
* \return If the parameters are valid and supported, return
|
|
* a buffer size in bytes that guarantees that
|
|
* psa_asymmetric_sign() will not fail with
|
|
* #PSA_ERROR_BUFFER_TOO_SMALL.
|
|
* If the parameters are a valid combination that is not supported
|
|
* by the implementation, this macro either shall return either a
|
|
* sensible size or 0.
|
|
* If the parameters are not valid, the
|
|
* return value is unspecified.
|
|
*/
|
|
#define PSA_KEY_EXPORT_MAX_SIZE(key_type, key_bits) \
|
|
(PSA_KEY_TYPE_IS_UNSTRUCTURED(key_type) ? PSA_BITS_TO_BYTES(key_bits) : \
|
|
(key_type) == PSA_KEY_TYPE_RSA_KEYPAIR ? PSA_KEY_EXPORT_RSA_KEYPAIR_MAX_SIZE(key_bits) : \
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|
(key_type) == PSA_KEY_TYPE_RSA_PUBLIC_KEY ? PSA_KEY_EXPORT_RSA_PUBLIC_KEY_MAX_SIZE(key_bits) : \
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|
(key_type) == PSA_KEY_TYPE_DSA_KEYPAIR ? PSA_KEY_EXPORT_DSA_KEYPAIR_MAX_SIZE(key_bits) : \
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|
(key_type) == PSA_KEY_TYPE_DSA_PUBLIC_KEY ? PSA_KEY_EXPORT_DSA_PUBLIC_KEY_MAX_SIZE(key_bits) : \
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|
PSA_KEY_TYPE_IS_ECC_KEYPAIR(key_type) ? PSA_KEY_EXPORT_ECC_KEYPAIR_MAX_SIZE(key_bits) : \
|
|
PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY(key_type) ? PSA_KEY_EXPORT_ECC_PUBLIC_KEY_MAX_SIZE(key_bits) : \
|
|
0)
|
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|
|
#endif /* PSA_CRYPTO_SIZES_H */
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