/** * \file gcm.h * * \brief Galois/Counter mode for AES * * Copyright (C) 2006-2013, Brainspark B.V. * * This file is part of PolarSSL (http://www.polarssl.org) * Lead Maintainer: Paul Bakker * * 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 "aes.h" #ifdef _MSC_VER #include typedef UINT64 uint64_t; #else #include #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 { aes_context aes_ctx; /*!< AES 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 key encryption key * \param keysize must be 128, 192 or 256 * * \return 0 if successful, or POLARSSL_ERR_AES_INVALID_KEY_LENGTH */ int gcm_init( gcm_context *ctx, const unsigned char *key, unsigned int keysize ); /** * \brief GCM buffer encryption/decryption using AES * * \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 AES * * \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 Checkup routine * * \return 0 if successful, or 1 if the test failed */ int gcm_self_test( int verbose ); #ifdef __cplusplus } #endif #endif /* gcm.h */