327 lines
14 KiB
C
327 lines
14 KiB
C
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/**
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* \file gcm.h
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*
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* \brief This file contains GCM definitions and functions.
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*
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* The Galois/Counter Mode (GCM) for 128-bit block ciphers is defined
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* in <em>D. McGrew, J. Viega, The Galois/Counter Mode of Operation
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* (GCM), Natl. Inst. Stand. Technol.</em>
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*
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* For more information on GCM, see <em>NIST SP 800-38D: Recommendation for
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* Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC</em>.
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*
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*/
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/*
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* Copyright (C) 2006-2018, Arm Limited (or its affiliates), 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 MBEDTLS_GCM_H
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#define MBEDTLS_GCM_H
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#include "cipher.h"
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#include <stdint.h>
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#define MBEDTLS_GCM_ENCRYPT 1
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#define MBEDTLS_GCM_DECRYPT 0
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#define MBEDTLS_ERR_GCM_AUTH_FAILED -0x0012 /**< Authenticated decryption failed. */
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/* MBEDTLS_ERR_GCM_HW_ACCEL_FAILED is deprecated and should not be used. */
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#define MBEDTLS_ERR_GCM_HW_ACCEL_FAILED -0x0013 /**< GCM hardware accelerator failed. */
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#define MBEDTLS_ERR_GCM_BAD_INPUT -0x0014 /**< Bad input parameters to function. */
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#ifdef __cplusplus
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extern "C" {
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#endif
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#if !defined(MBEDTLS_GCM_ALT)
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/**
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* \brief The GCM context structure.
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*/
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typedef struct mbedtls_gcm_context
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{
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mbedtls_cipher_context_t cipher_ctx; /*!< The cipher context used. */
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uint64_t HL[16]; /*!< Precalculated HTable low. */
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uint64_t HH[16]; /*!< Precalculated HTable high. */
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uint64_t len; /*!< The total length of the encrypted data. */
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uint64_t add_len; /*!< The total length of the additional data. */
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unsigned char base_ectr[16]; /*!< The first ECTR for tag. */
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unsigned char y[16]; /*!< The Y working value. */
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unsigned char buf[16]; /*!< The buf working value. */
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int mode; /*!< The operation to perform:
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#MBEDTLS_GCM_ENCRYPT or
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#MBEDTLS_GCM_DECRYPT. */
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}
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mbedtls_gcm_context;
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#else /* !MBEDTLS_GCM_ALT */
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#include "gcm_alt.h"
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#endif /* !MBEDTLS_GCM_ALT */
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/**
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* \brief This function initializes the specified GCM context,
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* to make references valid, and prepares the context
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* for mbedtls_gcm_setkey() or mbedtls_gcm_free().
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*
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* The function does not bind the GCM context to a particular
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* cipher, nor set the key. For this purpose, use
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* mbedtls_gcm_setkey().
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*
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* \param ctx The GCM context to initialize. This must not be \c NULL.
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*/
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void mbedtls_gcm_init( mbedtls_gcm_context *ctx );
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/**
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* \brief This function associates a GCM context with a
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* cipher algorithm and a key.
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*
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* \param ctx The GCM context. This must be initialized.
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* \param cipher The 128-bit block cipher to use.
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* \param key The encryption key. This must be a readable buffer of at
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* least \p keybits bits.
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* \param keybits The key size in bits. Valid options are:
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* <ul><li>128 bits</li>
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* <li>192 bits</li>
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* <li>256 bits</li></ul>
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*
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* \return \c 0 on success.
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* \return A cipher-specific error code on failure.
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*/
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int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
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mbedtls_cipher_id_t cipher,
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const unsigned char *key,
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unsigned int keybits );
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/**
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* \brief This function performs GCM encryption or decryption of a buffer.
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*
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* \note For encryption, the output buffer can be the same as the
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* input buffer. For decryption, the output buffer cannot be
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* the same as input buffer. If the buffers overlap, the output
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* buffer must trail at least 8 Bytes behind the input buffer.
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*
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* \warning When this function performs a decryption, it outputs the
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* authentication tag and does not verify that the data is
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* authentic. You should use this function to perform encryption
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* only. For decryption, use mbedtls_gcm_auth_decrypt() instead.
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*
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* \param ctx The GCM context to use for encryption or decryption. This
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* must be initialized.
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* \param mode The operation to perform:
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* - #MBEDTLS_GCM_ENCRYPT to perform authenticated encryption.
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* The ciphertext is written to \p output and the
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* authentication tag is written to \p tag.
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* - #MBEDTLS_GCM_DECRYPT to perform decryption.
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* The plaintext is written to \p output and the
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* authentication tag is written to \p tag.
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* Note that this mode is not recommended, because it does
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* not verify the authenticity of the data. For this reason,
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* you should use mbedtls_gcm_auth_decrypt() instead of
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* calling this function in decryption mode.
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* \param length The length of the input data, which is equal to the length
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* of the output data.
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* \param iv The initialization vector. This must be a readable buffer of
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* at least \p iv_len Bytes.
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* \param iv_len The length of the IV.
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* \param add The buffer holding the additional data. This must be of at
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* least that size in Bytes.
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* \param add_len The length of the additional data.
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* \param input The buffer holding the input data. If \p length is greater
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* than zero, this must be a readable buffer of at least that
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* size in Bytes.
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* \param output The buffer for holding the output data. If \p length is greater
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* than zero, this must be a writable buffer of at least that
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* size in Bytes.
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* \param tag_len The length of the tag to generate.
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* \param tag The buffer for holding the tag. This must be a readable
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* buffer of at least \p tag_len Bytes.
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*
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* \return \c 0 if the encryption or decryption was performed
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* successfully. Note that in #MBEDTLS_GCM_DECRYPT mode,
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* this does not indicate that the data is authentic.
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* \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths or pointers are
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* not valid or a cipher-specific error code if the encryption
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* or decryption failed.
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*/
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int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
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int mode,
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size_t length,
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const unsigned char *iv,
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size_t iv_len,
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const unsigned char *add,
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size_t add_len,
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const unsigned char *input,
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unsigned char *output,
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size_t tag_len,
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unsigned char *tag );
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/**
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* \brief This function performs a GCM authenticated decryption of a
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* buffer.
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*
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* \note For decryption, the output buffer cannot be the same as
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* input buffer. If the buffers overlap, the output buffer
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* must trail at least 8 Bytes behind the input buffer.
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*
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* \param ctx The GCM context. This must be initialized.
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* \param length The length of the ciphertext to decrypt, which is also
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* the length of the decrypted plaintext.
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* \param iv The initialization vector. This must be a readable buffer
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* of at least \p iv_len Bytes.
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* \param iv_len The length of the IV.
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* \param add The buffer holding the additional data. This must be of at
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* least that size in Bytes.
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* \param add_len The length of the additional data.
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* \param tag The buffer holding the tag to verify. This must be a
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* readable buffer of at least \p tag_len Bytes.
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* \param tag_len The length of the tag to verify.
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* \param input The buffer holding the ciphertext. If \p length is greater
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* than zero, this must be a readable buffer of at least that
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* size.
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* \param output The buffer for holding the decrypted plaintext. If \p length
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* is greater than zero, this must be a writable buffer of at
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* least that size.
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*
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* \return \c 0 if successful and authenticated.
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* \return #MBEDTLS_ERR_GCM_AUTH_FAILED if the tag does not match.
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* \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths or pointers are
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* not valid or a cipher-specific error code if the decryption
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* failed.
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*/
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int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
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size_t length,
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const unsigned char *iv,
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size_t iv_len,
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const unsigned char *add,
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size_t add_len,
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const unsigned char *tag,
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size_t tag_len,
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const unsigned char *input,
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unsigned char *output );
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/**
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* \brief This function starts a GCM encryption or decryption
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* operation.
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*
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* \param ctx The GCM context. This must be initialized.
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* \param mode The operation to perform: #MBEDTLS_GCM_ENCRYPT or
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* #MBEDTLS_GCM_DECRYPT.
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* \param iv The initialization vector. This must be a readable buffer of
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* at least \p iv_len Bytes.
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* \param iv_len The length of the IV.
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* \param add The buffer holding the additional data, or \c NULL
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* if \p add_len is \c 0.
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* \param add_len The length of the additional data. If \c 0,
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* \p add may be \c NULL.
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*
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* \return \c 0 on success.
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*/
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int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
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int mode,
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const unsigned char *iv,
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size_t iv_len,
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const unsigned char *add,
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size_t add_len );
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/**
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* \brief This function feeds an input buffer into an ongoing GCM
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* encryption or decryption operation.
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*
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* ` The function expects input to be a multiple of 16
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* Bytes. Only the last call before calling
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* mbedtls_gcm_finish() can be less than 16 Bytes.
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*
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* \note For decryption, the output buffer cannot be the same as
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* input buffer. If the buffers overlap, the output buffer
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* must trail at least 8 Bytes behind the input buffer.
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*
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* \param ctx The GCM context. This must be initialized.
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* \param length The length of the input data. This must be a multiple of
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* 16 except in the last call before mbedtls_gcm_finish().
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* \param input The buffer holding the input data. If \p length is greater
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* than zero, this must be a readable buffer of at least that
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* size in Bytes.
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* \param output The buffer for holding the output data. If \p length is
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* greater than zero, this must be a writable buffer of at
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* least that size in Bytes.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
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*/
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int mbedtls_gcm_update( mbedtls_gcm_context *ctx,
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size_t length,
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const unsigned char *input,
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unsigned char *output );
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/**
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* \brief This function finishes the GCM operation and generates
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* the authentication tag.
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*
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* It wraps up the GCM stream, and generates the
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* tag. The tag can have a maximum length of 16 Bytes.
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*
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* \param ctx The GCM context. This must be initialized.
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* \param tag The buffer for holding the tag. This must be a readable
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* buffer of at least \p tag_len Bytes.
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* \param tag_len The length of the tag to generate. This must be at least
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* four.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
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*/
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int mbedtls_gcm_finish( mbedtls_gcm_context *ctx,
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unsigned char *tag,
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size_t tag_len );
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/**
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* \brief This function clears a GCM context and the underlying
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* cipher sub-context.
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*
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* \param ctx The GCM context to clear. If this is \c NULL, the call has
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* no effect. Otherwise, this must be initialized.
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*/
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void mbedtls_gcm_free( mbedtls_gcm_context *ctx );
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#if defined(MBEDTLS_SELF_TEST)
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/**
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* \brief The GCM checkup routine.
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*
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* \return \c 0 on success.
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* \return \c 1 on failure.
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*/
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int mbedtls_gcm_self_test( int verbose );
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#endif /* MBEDTLS_SELF_TEST */
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#ifdef __cplusplus
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}
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#endif
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#endif /* gcm.h */
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