/** * \file psa/crypto_sizes.h * * \brief PSA cryptography module: Mbed TLS buffer size macros * * This file contains the definitions of macros that are useful to * compute buffer sizes. The signatures and semantics of these macros * are standardized, but the definitions are not, because they depend on * the available algorithms and, in some cases, on permitted tolerances * on buffer sizes. * * Macros that compute sizes whose values do not depend on the * implementation are in crypto.h. */ /* * Copyright (C) 2018, 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) */ #ifndef PSA_CRYPTO_SIZES_H #define PSA_CRYPTO_SIZES_H /* Include the Mbed TLS configuration file, the way Mbed TLS does it * in each of its header files. */ #if !defined(MBEDTLS_CONFIG_FILE) #include "../mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_SHA512_C) #define PSA_HASH_MAX_SIZE 64 #define PSA_HMAC_MAX_HASH_BLOCK_SIZE 128 #else #define PSA_HASH_MAX_SIZE 32 #define PSA_HMAC_MAX_HASH_BLOCK_SIZE 64 #endif /** The size of the output of psa_mac_finish(), in bytes. * * This is also the MAC size that psa_mac_verify() expects. * * \param key_type The type of the MAC key. * \param key_bits The size of the MAC key in bits. * \param alg A MAC algorithm (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_MAC(alg) is true). * * \return The MAC size for the specified algorithm with * the specified key parameters. * \return 0 if the MAC algorithm is not recognized. * \return Either 0 or the correct size for a MAC algorithm that * the implementation recognizes, but does not support. * \return Unspecified if the key parameters are not consistent * with the algorithm. */ #define PSA_MAC_FINAL_SIZE(key_type, key_bits, alg) \ (PSA_ALG_IS_HMAC(alg) ? PSA_HASH_SIZE(PSA_ALG_HMAC_HASH(alg)) : \ PSA_ALG_IS_BLOCK_CIPHER_MAC(alg) ? PSA_BLOCK_CIPHER_BLOCK_SIZE(key_type) : \ 0) /** The maximum size of the output of psa_aead_encrypt(), in bytes. * * If the size of the ciphertext buffer is at least this large, it is * guaranteed that psa_aead_encrypt() will not fail due to an * insufficient buffer size. Depending on the algorithm, the actual size of * the ciphertext may be smaller. * * \param alg An AEAD algorithm * (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_AEAD(alg) is true). * \param plaintext_length Size of the plaintext in bytes. * * \return The AEAD ciphertext size for the specified * algorithm. * If the AEAD algorithm is not recognized, return 0. * An implementation may return either 0 or a * correct size for an AEAD algorithm that it * recognizes, but does not support. */ #define PSA_AEAD_ENCRYPT_OUTPUT_SIZE(alg, plaintext_length) \ (PSA_AEAD_TAG_SIZE(alg) != 0 ? \ (plaintext_length) + PSA_AEAD_TAG_SIZE(alg) : \ 0) /** The maximum size of the output of psa_aead_decrypt(), in bytes. * * If the size of the plaintext buffer is at least this large, it is * guaranteed that psa_aead_decrypt() will not fail due to an * insufficient buffer size. Depending on the algorithm, the actual size of * the plaintext may be smaller. * * \param alg An AEAD algorithm * (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_AEAD(alg) is true). * \param ciphertext_length Size of the plaintext in bytes. * * \return The AEAD ciphertext size for the specified * algorithm. * If the AEAD algorithm is not recognized, return 0. * An implementation may return either 0 or a * correct size for an AEAD algorithm that it * recognizes, but does not support. */ #define PSA_AEAD_DECRYPT_OUTPUT_SIZE(alg, ciphertext_length) \ (PSA_AEAD_TAG_SIZE(alg) != 0 ? \ (plaintext_length) - PSA_AEAD_TAG_SIZE(alg) : \ 0) /** Safe signature buffer size for psa_asymmetric_sign(). * * This macro returns a safe buffer size for a signature using a key * of the specified type and size, with the specified algorithm. * Note that the actual size of the signature may be smaller * (some algorithms produce a variable-size signature). * * \warning This function may call its arguments multiple times or * zero times, so you should not pass arguments that contain * side effects. * * \param key_type An asymmetric key type (this may indifferently be a * key pair type or a public key type). * \param key_bits The size of the key in bits. * \param alg The signature algorithm. * * \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_ASYMMETRIC_SIGN_OUTPUT_SIZE(key_type, key_bits, alg) \ (PSA_KEY_TYPE_IS_RSA(key_type) ? ((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \ PSA_KEY_TYPE_IS_ECC(key_type) ? PSA_ECDSA_SIGNATURE_SIZE(key_bits) : \ ((void)alg, 0)) #define PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \ (PSA_KEY_TYPE_IS_RSA(key_type) ? \ ((void)alg, PSA_BITS_TO_BYTES(key_bits)) : \ 0) #define PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE(key_type, key_bits, alg) \ (PSA_KEY_TYPE_IS_RSA(key_type) ? \ PSA_BITS_TO_BYTES(key_bits) - PSA_RSA_MINIMUM_PADDING_SIZE(alg) : \ 0) #endif /* PSA_CRYPTO_SIZES_H */