/usr/include/polarssl/gcm.h is in libpolarssl-dev 1.3.4-1.
This file is owned by root:root, with mode 0o644.
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* \file gcm.h
*
* \brief Galois/Counter mode for 128-bit block ciphers
*
* Copyright (C) 2006-2013, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef POLARSSL_GCM_H
#define POLARSSL_GCM_H
#include "cipher.h"
#if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
#include <basetsd.h>
typedef UINT32 uint32_t;
typedef UINT64 uint64_t;
#else
#include <stdint.h>
#endif
#define GCM_ENCRYPT 1
#define GCM_DECRYPT 0
#define POLARSSL_ERR_GCM_AUTH_FAILED -0x0012 /**< Authenticated decryption failed. */
#define POLARSSL_ERR_GCM_BAD_INPUT -0x0014 /**< Bad input parameters to function. */
#ifdef __cplusplus
extern "C" {
#endif
/**
* \brief GCM context structure
*/
typedef struct {
cipher_context_t cipher_ctx;/*!< cipher context used */
uint64_t HL[16]; /*!< Precalculated HTable */
uint64_t HH[16]; /*!< Precalculated HTable */
uint64_t len; /*!< Total data length */
uint64_t add_len; /*!< Total add length */
unsigned char base_ectr[16];/*!< First ECTR for tag */
unsigned char y[16]; /*!< Y working value */
unsigned char buf[16]; /*!< buf working value */
int mode; /*!< Encrypt or Decrypt */
}
gcm_context;
/**
* \brief GCM initialization (encryption)
*
* \param ctx GCM context to be initialized
* \param cipher cipher to use (a 128-bit block cipher)
* \param key encryption key
* \param keysize must be 128, 192 or 256
*
* \return 0 if successful, or a cipher specific error code
*/
int gcm_init( gcm_context *ctx, cipher_id_t cipher, const unsigned char *key,
unsigned int keysize );
/**
* \brief GCM buffer encryption/decryption using a block cipher
*
* \note On encryption, the output buffer can be the same as the input buffer.
* On decryption, the output buffer cannot be the same as input buffer.
* If buffers overlap, the output buffer must trail at least 8 bytes
* behind the input buffer.
*
* \param ctx GCM context
* \param mode GCM_ENCRYPT or GCM_DECRYPT
* \param length length of the input data
* \param iv initialization vector
* \param iv_len length of IV
* \param add additional data
* \param add_len length of additional data
* \param input buffer holding the input data
* \param output buffer for holding the output data
* \param tag_len length of the tag to generate
* \param tag buffer for holding the tag
*
* \return 0 if successful
*/
int gcm_crypt_and_tag( 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 GCM buffer authenticated decryption using a block cipher
*
* \note On decryption, the output buffer cannot be the same as input buffer.
* If buffers overlap, the output buffer must trail at least 8 bytes
* behind the input buffer.
*
* \param ctx GCM context
* \param length length of the input data
* \param iv initialization vector
* \param iv_len length of IV
* \param add additional data
* \param add_len length of additional data
* \param tag buffer holding the tag
* \param tag_len length of the tag
* \param input buffer holding the input data
* \param output buffer for holding the output data
*
* \return 0 if successful and authenticated,
* POLARSSL_ERR_GCM_AUTH_FAILED if tag does not match
*/
int gcm_auth_decrypt( 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 Generic GCM stream start function
*
* \param ctx GCM context
* \param mode GCM_ENCRYPT or GCM_DECRYPT
* \param iv initialization vector
* \param iv_len length of IV
* \param add additional data (or NULL if length is 0)
* \param add_len length of additional data
*
* \return 0 if successful
*/
int gcm_starts( gcm_context *ctx,
int mode,
const unsigned char *iv,
size_t iv_len,
const unsigned char *add,
size_t add_len );
/**
* \brief Generic GCM update function. Encrypts/decrypts using the
* given GCM context. Expects input to be a multiple of 16
* bytes! Only the last call before gcm_finish() can be less
* than 16 bytes!
*
* \note On decryption, the output buffer cannot be the same as input buffer.
* If buffers overlap, the output buffer must trail at least 8 bytes
* behind the input buffer.
*
* \param ctx GCM context
* \param length length of the input data
* \param input buffer holding the input data
* \param output buffer for holding the output data
*
* \return 0 if successful or POLARSSL_ERR_GCM_BAD_INPUT
*/
int gcm_update( gcm_context *ctx,
size_t length,
const unsigned char *input,
unsigned char *output );
/**
* \brief Generic GCM finalisation function. Wraps up the GCM stream
* and generates the tag. The tag can have a maximum length of
* 16 bytes.
*
* \param ctx GCM context
* \param tag buffer for holding the tag (may be NULL if tag_len is 0)
* \param tag_len length of the tag to generate
*
* \return 0 if successful or POLARSSL_ERR_GCM_BAD_INPUT
*/
int gcm_finish( gcm_context *ctx,
unsigned char *tag,
size_t tag_len );
/**
* \brief Free a GCM context and underlying cipher sub-context
*
* \param ctx GCM context to free
*/
void gcm_free( gcm_context *ctx );
/**
* \brief Checkup routine
*
* \return 0 if successful, or 1 if the test failed
*/
int gcm_self_test( int verbose );
#ifdef __cplusplus
}
#endif
#endif /* gcm.h */
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