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- /**
- * \file gcm.h
- *
- * \brief Galois/Counter Mode (GCM) for 128-bit block ciphers, as defined
- * in <em>D. McGrew, J. Viega, The Galois/Counter Mode of Operation
- * (GCM), Natl. Inst. Stand. Technol.</em>
- *
- * For more information on GCM, see <em>NIST SP 800-38D: Recommendation for
- * Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC</em>.
- *
- */
- /*
- * Copyright (C) 2006-2018, Arm Limited (or its affiliates), 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 MBEDTLS_GCM_H
- #define MBEDTLS_GCM_H
- #include "cipher.h"
- #include <stdint.h>
- #define MBEDTLS_GCM_ENCRYPT 1
- #define MBEDTLS_GCM_DECRYPT 0
- #define MBEDTLS_ERR_GCM_AUTH_FAILED -0x0012 /**< Authenticated decryption failed. */
- #define MBEDTLS_ERR_GCM_HW_ACCEL_FAILED -0x0013 /**< GCM hardware accelerator failed. */
- #define MBEDTLS_ERR_GCM_BAD_INPUT -0x0014 /**< Bad input parameters to function. */
- #if !defined(MBEDTLS_GCM_ALT)
- #ifdef __cplusplus
- extern "C" {
- #endif
- /**
- * \brief The GCM context structure.
- */
- typedef struct {
- mbedtls_cipher_context_t cipher_ctx; /*!< The cipher context used. */
- uint64_t HL[16]; /*!< Precalculated HTable low. */
- uint64_t HH[16]; /*!< Precalculated HTable high. */
- uint64_t len; /*!< The total length of the encrypted data. */
- uint64_t add_len; /*!< The total length of the additional data. */
- unsigned char base_ectr[16]; /*!< The first ECTR for tag. */
- unsigned char y[16]; /*!< The Y working value. */
- unsigned char buf[16]; /*!< The buf working value. */
- int mode; /*!< The operation to perform:
- #MBEDTLS_GCM_ENCRYPT or
- #MBEDTLS_GCM_DECRYPT. */
- }
- mbedtls_gcm_context;
- /**
- * \brief This function initializes the specified GCM context,
- * to make references valid, and prepares the context
- * for mbedtls_gcm_setkey() or mbedtls_gcm_free().
- *
- * The function does not bind the GCM context to a particular
- * cipher, nor set the key. For this purpose, use
- * mbedtls_gcm_setkey().
- *
- * \param ctx The GCM context to initialize.
- */
- void mbedtls_gcm_init( mbedtls_gcm_context *ctx );
- /**
- * \brief This function associates a GCM context with a
- * cipher algorithm and a key.
- *
- * \param ctx The GCM context to initialize.
- * \param cipher The 128-bit block cipher to use.
- * \param key The encryption key.
- * \param keybits The key size in bits. Valid options are:
- * <ul><li>128 bits</li>
- * <li>192 bits</li>
- * <li>256 bits</li></ul>
- *
- * \return \c 0 on success, or a cipher specific error code.
- */
- int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
- mbedtls_cipher_id_t cipher,
- const unsigned char *key,
- unsigned int keybits );
- /**
- * \brief This function performs GCM encryption or decryption of a buffer.
- *
- * \note For encryption, the output buffer can be the same as the input buffer.
- * For decryption, the output buffer cannot be the same as input buffer.
- * If the buffers overlap, the output buffer must trail at least 8 Bytes
- * behind the input buffer.
- *
- * \warning When this function performs a decryption, it outputs the
- * authentication tag and does not verify that the data is
- * authentic. You should use this function to perform encryption
- * only. For decryption, use mbedtls_gcm_auth_decrypt() instead.
- *
- * \param ctx The GCM context to use for encryption or decryption.
- * \param mode The operation to perform:
- * - #MBEDTLS_GCM_ENCRYPT to perform authenticated encryption.
- * The ciphertext is written to \p output and the
- * authentication tag is written to \p tag.
- * - #MBEDTLS_GCM_DECRYPT to perform decryption.
- * The plaintext is written to \p output and the
- * authentication tag is written to \p tag.
- * Note that this mode is not recommended, because it does
- * not verify the authenticity of the data. For this reason,
- * you should use mbedtls_gcm_auth_decrypt() instead of
- * calling this function in decryption mode.
- * \param length The length of the input data, which is equal to the length
- * of the output data.
- * \param iv The initialization vector.
- * \param iv_len The length of the IV.
- * \param add The buffer holding the additional data.
- * \param add_len The length of the additional data.
- * \param input The buffer holding the input data. Its size is \b length.
- * \param output The buffer for holding the output data. It must have room
- * for \b length bytes.
- * \param tag_len The length of the tag to generate.
- * \param tag The buffer for holding the tag.
- *
- * \return \c 0 if the encryption or decryption was performed
- * successfully. Note that in #MBEDTLS_GCM_DECRYPT mode,
- * this does not indicate that the data is authentic.
- * \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid.
- * \return #MBEDTLS_ERR_GCM_HW_ACCEL_FAILED or a cipher-specific
- * error code if the encryption or decryption failed.
- */
- int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
- int mode,
- size_t length,
- const unsigned char *iv,
- size_t iv_len,
- const unsigned char *add,
- size_t add_len,
- const unsigned char *input,
- unsigned char *output,
- size_t tag_len,
- unsigned char *tag );
- /**
- * \brief This function performs a GCM authenticated decryption of a
- * buffer.
- *
- * \note For decryption, the output buffer cannot be the same as input buffer.
- * If the buffers overlap, the output buffer must trail at least 8 Bytes
- * behind the input buffer.
- *
- * \param ctx The GCM context.
- * \param length The length of the ciphertext to decrypt, which is also
- * the length of the decrypted plaintext.
- * \param iv The initialization vector.
- * \param iv_len The length of the IV.
- * \param add The buffer holding the additional data.
- * \param add_len The length of the additional data.
- * \param tag The buffer holding the tag to verify.
- * \param tag_len The length of the tag to verify.
- * \param input The buffer holding the ciphertext. Its size is \b length.
- * \param output The buffer for holding the decrypted plaintext. It must
- * have room for \b length bytes.
- *
- * \return \c 0 if successful and authenticated.
- * \return #MBEDTLS_ERR_GCM_AUTH_FAILED if the tag does not match.
- * \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid.
- * \return #MBEDTLS_ERR_GCM_HW_ACCEL_FAILED or a cipher-specific
- * error code if the decryption failed.
- */
- int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
- size_t length,
- const unsigned char *iv,
- size_t iv_len,
- const unsigned char *add,
- size_t add_len,
- const unsigned char *tag,
- size_t tag_len,
- const unsigned char *input,
- unsigned char *output );
- /**
- * \brief This function starts a GCM encryption or decryption
- * operation.
- *
- * \param ctx The GCM context.
- * \param mode The operation to perform: #MBEDTLS_GCM_ENCRYPT or
- * #MBEDTLS_GCM_DECRYPT.
- * \param iv The initialization vector.
- * \param iv_len The length of the IV.
- * \param add The buffer holding the additional data, or NULL if \p add_len is 0.
- * \param add_len The length of the additional data. If 0, \p add is NULL.
- *
- * \return \c 0 on success.
- */
- int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
- int mode,
- const unsigned char *iv,
- size_t iv_len,
- const unsigned char *add,
- size_t add_len );
- /**
- * \brief This function feeds an input buffer into an ongoing GCM
- * encryption or decryption operation.
- *
- * ` The function expects input to be a multiple of 16
- * Bytes. Only the last call before calling
- * mbedtls_gcm_finish() can be less than 16 Bytes.
- *
- * \note For decryption, the output buffer cannot be the same as input buffer.
- * If the buffers overlap, the output buffer must trail at least 8 Bytes
- * behind the input buffer.
- *
- * \param ctx The GCM context.
- * \param length The length of the input data. This must be a multiple of 16 except in the last call before mbedtls_gcm_finish().
- * \param input The buffer holding the input data.
- * \param output The buffer for holding the output data.
- *
- * \return \c 0 on success, or #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
- */
- int mbedtls_gcm_update( mbedtls_gcm_context *ctx,
- size_t length,
- const unsigned char *input,
- unsigned char *output );
- /**
- * \brief This function finishes the GCM operation and generates
- * the authentication tag.
- *
- * It wraps up the GCM stream, and generates the
- * tag. The tag can have a maximum length of 16 Bytes.
- *
- * \param ctx The GCM context.
- * \param tag The buffer for holding the tag.
- * \param tag_len The length of the tag to generate. Must be at least four.
- *
- * \return \c 0 on success, or #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
- */
- int mbedtls_gcm_finish( mbedtls_gcm_context *ctx,
- unsigned char *tag,
- size_t tag_len );
- /**
- * \brief This function clears a GCM context and the underlying
- * cipher sub-context.
- *
- * \param ctx The GCM context to clear.
- */
- void mbedtls_gcm_free( mbedtls_gcm_context *ctx );
- #ifdef __cplusplus
- }
- #endif
- #else /* !MBEDTLS_GCM_ALT */
- #include "gcm_alt.h"
- #endif /* !MBEDTLS_GCM_ALT */
- #ifdef __cplusplus
- extern "C" {
- #endif
- /**
- * \brief The GCM checkup routine.
- *
- * \return \c 0 on success, or \c 1 on failure.
- */
- int mbedtls_gcm_self_test( int verbose );
- #ifdef __cplusplus
- }
- #endif
- #endif /* gcm.h */
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