220 lines
7.4 KiB
C
220 lines
7.4 KiB
C
/**
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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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*
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* Copyright (C) 2006-2013, Brainspark B.V.
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*
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* This file is part of PolarSSL (http://www.polarssl.org)
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* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef POLARSSL_GCM_H
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#define POLARSSL_GCM_H
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#include "cipher.h"
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#if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
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#include <basetsd.h>
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typedef UINT32 uint32_t;
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typedef UINT64 uint64_t;
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#else
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#include <stdint.h>
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#endif
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#define GCM_ENCRYPT 1
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#define GCM_DECRYPT 0
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#define POLARSSL_ERR_GCM_AUTH_FAILED -0x0012 /**< Authenticated decryption failed. */
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#define POLARSSL_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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/**
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* \brief GCM context structure
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*/
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typedef struct {
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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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}
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gcm_context;
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/**
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* \brief GCM initialization (encryption)
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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 keysize must be 128, 192 or 256
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*
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* \return 0 if successful, or a cipher specific error code
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*/
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int gcm_init( gcm_context *ctx, cipher_id_t cipher, const unsigned char *key,
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unsigned int keysize );
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/**
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* \brief GCM buffer encryption/decryption using a block cipher
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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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* behind the input buffer.
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*
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* \param ctx GCM context
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* \param mode GCM_ENCRYPT or 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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*
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* \return 0 if successful
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*/
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int gcm_crypt_and_tag( 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 GCM buffer authenticated decryption using a block cipher
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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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* 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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*
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* \return 0 if successful and authenticated,
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* POLARSSL_ERR_GCM_AUTH_FAILED if tag does not match
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*/
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int gcm_auth_decrypt( 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 Generic GCM stream start function
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*
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* \param ctx GCM context
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* \param mode GCM_ENCRYPT or 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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*
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* \return 0 if successful
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*/
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int gcm_starts( 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 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 gcm_finish() can be less
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* than 16 bytes!
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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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* 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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*
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* \return 0 if successful or POLARSSL_ERR_GCM_BAD_INPUT
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*/
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int gcm_update( 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 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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*
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* \param ctx GCM context
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* \param tag buffer for holding the tag (may be NULL if tag_len is 0)
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* \param tag_len length of the tag to generate
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*
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* \return 0 if successful or POLARSSL_ERR_GCM_BAD_INPUT
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*/
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int gcm_finish( 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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*
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* \param ctx GCM context to free
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*/
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void gcm_free( gcm_context *ctx );
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/**
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* \brief Checkup routine
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*
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* \return 0 if successful, or 1 if the test failed
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*/
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int gcm_self_test( int verbose );
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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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