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Improve GCM documentation
- Rephrase file/function/parameter/enum/define/error descriptions into full and clear sentences. - Make sure to adhere to the Arm writing guidelines. - Fix missing/incorrect Doxygen tags. - Standardize terminology used within the file. GitHub PR: #1324
This commit is contained in:
Rose Zadik
Jaeden Amero
parent
41ad082484
commit
17b4f7fc60
@ -1,10 +1,16 @@
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/**
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* \file gcm.h
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*
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* \brief Galois/Counter mode for 128-bit block ciphers
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* \brief Galois/Counter Mode (GCM) for 128-bit block ciphers, as 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) 2006-2015, ARM Limited, All Rights Reserved
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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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@ -19,8 +25,9 @@
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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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* 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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@ -42,39 +49,49 @@ extern "C" {
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#endif
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/**
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* \brief GCM context structure
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* \brief The GCM context structure.
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*/
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typedef struct {
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mbedtls_cipher_context_t cipher_ctx;/*!< cipher context used */
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uint64_t HL[16]; /*!< Precalculated HTable */
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uint64_t HH[16]; /*!< Precalculated HTable */
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uint64_t len; /*!< Total data length */
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uint64_t add_len; /*!< Total add length */
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unsigned char base_ectr[16];/*!< First ECTR for tag */
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unsigned char y[16]; /*!< Y working value */
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unsigned char buf[16]; /*!< buf working value */
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int mode; /*!< Encrypt or Decrypt */
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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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/**
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* \brief Initialize GCM context (just makes references valid)
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* Makes the context ready for mbedtls_gcm_setkey() or
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* mbedtls_gcm_free().
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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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* \param ctx GCM context to initialize
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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.
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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 GCM initialization (encryption)
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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 GCM context to be initialized
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* \param cipher cipher to use (a 128-bit block cipher)
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* \param key encryption key
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* \param keybits must be 128, 192 or 256
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* \param ctx The GCM context to initialize.
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* \param cipher The 128-bit block cipher to use.
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* \param key The encryption key.
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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 0 if successful, or a cipher specific error code
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* \return \c 0 on success, or a cipher specific error code.
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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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@ -82,26 +99,27 @@ int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
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unsigned int keybits );
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/**
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* \brief GCM buffer encryption/decryption using a block cipher
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* \brief This function performs GCM encryption or decryption of a buffer.
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*
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* \note On encryption, the output buffer can be the same as the input buffer.
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* On decryption, the output buffer cannot be the same as input buffer.
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* If buffers overlap, the output buffer must trail at least 8 bytes
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* \note For encryption, the output buffer can be the same as the input buffer.
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* For decryption, the output buffer cannot be the same as input buffer.
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* If the buffers overlap, the output buffer must trail at least 8 Bytes
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* behind the input buffer.
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*
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* \param ctx GCM context
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* \param mode MBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
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* \param length length of the input data
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* \param iv initialization vector
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* \param iv_len length of IV
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* \param add additional data
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* \param add_len length of additional data
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* \param input buffer holding the input data
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* \param output buffer for holding the output data
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* \param tag_len length of the tag to generate
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* \param tag buffer for holding the tag
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* \param ctx The GCM context to use for encryption or decryption.
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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 length The length of the input data. This must be a multiple of 16 except in the last call before mbedtls_gcm_finish().
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* \param iv The initialization vector.
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* \param iv_len The length of the IV.
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* \param add The buffer holding the additional data.
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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.
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* \param output The buffer for holding the output data.
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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.
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*
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* \return 0 if successful
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* \return \c 0 on success.
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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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@ -116,25 +134,26 @@ int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
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unsigned char *tag );
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/**
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* \brief GCM buffer authenticated decryption using a block cipher
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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 On decryption, the output buffer cannot be the same as input buffer.
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* If buffers overlap, the output buffer must trail at least 8 bytes
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* \note For decryption, the output buffer cannot be the same as input buffer.
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* If the buffers overlap, the output buffer must trail at least 8 Bytes
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* behind the input buffer.
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*
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* \param ctx GCM context
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* \param length length of the input data
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* \param iv initialization vector
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* \param iv_len length of IV
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* \param add additional data
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* \param add_len length of additional data
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* \param tag buffer holding the tag
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* \param tag_len length of the tag
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* \param input buffer holding the input data
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* \param output buffer for holding the output data
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* \param ctx The GCM context.
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* \param length The length of the input data. This must be a multiple of 16 except in the last call before mbedtls_gcm_finish().
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* \param iv The initialization vector.
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* \param iv_len The length of the IV.
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* \param add The buffer holding the additional data.
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* \param add_len The length of the additional data.
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* \param tag The buffer holding the tag.
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* \param tag_len The length of the tag.
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* \param input The buffer holding the input data.
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* \param output The buffer for holding the output data.
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*
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* \return 0 if successful and authenticated,
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* MBEDTLS_ERR_GCM_AUTH_FAILED if tag does not match
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* \return 0 if successful and authenticated, or
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* #MBEDTLS_ERR_GCM_AUTH_FAILED if tag does not match.
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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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@ -148,16 +167,18 @@ int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
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unsigned char *output );
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/**
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* \brief Generic GCM stream start function
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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 GCM context
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* \param mode MBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
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* \param iv initialization vector
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* \param iv_len length of IV
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* \param add additional data (or NULL if length is 0)
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* \param add_len length of additional data
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* \param ctx The GCM context.
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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.
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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 NULL if \p add_len is 0.
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* \param add_len The length of the additional data. If 0, \p add is NULL.
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*
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* \return 0 if successful
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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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@ -167,21 +188,23 @@ int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
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size_t add_len );
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/**
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* \brief Generic GCM update function. Encrypts/decrypts using the
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* given GCM context. Expects input to be a multiple of 16
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* bytes! Only the last call before mbedtls_gcm_finish() can be less
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* than 16 bytes!
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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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* \note On decryption, the output buffer cannot be the same as input buffer.
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* If buffers overlap, the output buffer must trail at least 8 bytes
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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 input buffer.
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* If the buffers overlap, the output buffer must trail at least 8 Bytes
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* behind the input buffer.
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*
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* \param ctx GCM context
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* \param length length of the input data
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* \param input buffer holding the input data
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* \param output buffer for holding the output data
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* \param ctx The GCM context.
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* \param length The length of the input data. This must be a multiple of 16 except in the last call before mbedtls_gcm_finish().
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* \param input The buffer holding the input data.
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* \param output The buffer for holding the output data.
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*
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* \return 0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT
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* \return \c 0 on success, or #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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@ -189,24 +212,27 @@ int mbedtls_gcm_update( mbedtls_gcm_context *ctx,
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unsigned char *output );
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/**
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* \brief Generic GCM finalisation function. Wraps up the GCM stream
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* and generates the tag. The tag can have a maximum length of
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* 16 bytes.
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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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* \param ctx GCM context
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* \param tag buffer for holding the tag
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* \param tag_len length of the tag to generate (must be at least 4)
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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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* \return 0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT
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* \param ctx The GCM context.
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* \param tag The buffer for holding the tag.
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* \param tag_len The length of the tag to generate. Must be at least four.
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*
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* \return \c 0 on success, or #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 Free a GCM context and underlying cipher sub-context
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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 GCM context to free
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* \param ctx The GCM context to clear.
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*/
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void mbedtls_gcm_free( mbedtls_gcm_context *ctx );
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@ -223,9 +249,9 @@ extern "C" {
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#endif
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/**
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* \brief Checkup routine
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* \brief The GCM checkup routine.
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*
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* \return 0 if successful, or 1 if the test failed
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* \return \c 0 on success, or \c 1 on failure.
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*/
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int mbedtls_gcm_self_test( int verbose );
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