gcm.h

00001 /**
00002  * \file gcm.h
00003  *
00004  * \brief Galois/Counter mode for 128-bit block ciphers
00005  *
00006  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
00007  *  SPDX-License-Identifier: Apache-2.0
00008  *
00009  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00010  *  not use this file except in compliance with the License.
00011  *  You may obtain a copy of the License at
00012  *
00013  *  http://www.apache.org/licenses/LICENSE-2.0
00014  *
00015  *  Unless required by applicable law or agreed to in writing, software
00016  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00017  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00018  *  See the License for the specific language governing permissions and
00019  *  limitations under the License.
00020  *
00021  *  This file is part of mbed TLS (https://tls.mbed.org)
00022  */
00023 #ifndef MBEDTLS_GCM_H
00024 #define MBEDTLS_GCM_H
00025 
00026 #include "cipher.h"
00027 
00028 #include <stdint.h>
00029 
00030 #define MBEDTLS_GCM_ENCRYPT     1
00031 #define MBEDTLS_GCM_DECRYPT     0
00032 
00033 #define MBEDTLS_ERR_GCM_AUTH_FAILED                       -0x0012  /**< Authenticated decryption failed. */
00034 #define MBEDTLS_ERR_GCM_BAD_INPUT                         -0x0014  /**< Bad input parameters to function. */
00035 
00036 #ifdef __cplusplus
00037 extern "C" {
00038 #endif
00039 
00040 /**
00041  * \brief          GCM context structure
00042  */
00043 typedef struct {
00044     mbedtls_cipher_context_t cipher_ctx ;/*!< cipher context used */
00045     uint64_t HL[16];            /*!< Precalculated HTable */
00046     uint64_t HH[16];            /*!< Precalculated HTable */
00047     uint64_t len ;               /*!< Total data length */
00048     uint64_t add_len ;           /*!< Total add length */
00049     unsigned char base_ectr[16];/*!< First ECTR for tag */
00050     unsigned char y[16];        /*!< Y working value */
00051     unsigned char buf[16];      /*!< buf working value */
00052     int mode ;                   /*!< Encrypt or Decrypt */
00053 }
00054 mbedtls_gcm_context;
00055 
00056 /**
00057  * \brief           Initialize GCM context (just makes references valid)
00058  *                  Makes the context ready for mbedtls_gcm_setkey() or
00059  *                  mbedtls_gcm_free().
00060  *
00061  * \param ctx       GCM context to initialize
00062  */
00063 void mbedtls_gcm_init( mbedtls_gcm_context *ctx );
00064 
00065 /**
00066  * \brief           GCM initialization (encryption)
00067  *
00068  * \param ctx       GCM context to be initialized
00069  * \param cipher    cipher to use (a 128-bit block cipher)
00070  * \param key       encryption key
00071  * \param keybits   must be 128, 192 or 256
00072  *
00073  * \return          0 if successful, or a cipher specific error code
00074  */
00075 int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
00076                         mbedtls_cipher_id_t cipher,
00077                         const unsigned char *key,
00078                         unsigned int keybits );
00079 
00080 /**
00081  * \brief           GCM buffer encryption/decryption using a block cipher
00082  *
00083  * \note On encryption, the output buffer can be the same as the input buffer.
00084  *       On decryption, the output buffer cannot be the same as input buffer.
00085  *       If buffers overlap, the output buffer must trail at least 8 bytes
00086  *       behind the input buffer.
00087  *
00088  * \param ctx       GCM context
00089  * \param mode      MBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
00090  * \param length    length of the input data
00091  * \param iv        initialization vector
00092  * \param iv_len    length of IV
00093  * \param add       additional data
00094  * \param add_len   length of additional data
00095  * \param input     buffer holding the input data
00096  * \param output    buffer for holding the output data
00097  * \param tag_len   length of the tag to generate
00098  * \param tag       buffer for holding the tag
00099  *
00100  * \return         0 if successful
00101  */
00102 int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
00103                        int mode,
00104                        size_t length,
00105                        const unsigned char *iv,
00106                        size_t iv_len,
00107                        const unsigned char *add,
00108                        size_t add_len,
00109                        const unsigned char *input,
00110                        unsigned char *output,
00111                        size_t tag_len,
00112                        unsigned char *tag );
00113 
00114 /**
00115  * \brief           GCM buffer authenticated decryption using a block cipher
00116  *
00117  * \note On decryption, the output buffer cannot be the same as input buffer.
00118  *       If buffers overlap, the output buffer must trail at least 8 bytes
00119  *       behind the input buffer.
00120  *
00121  * \param ctx       GCM context
00122  * \param length    length of the input data
00123  * \param iv        initialization vector
00124  * \param iv_len    length of IV
00125  * \param add       additional data
00126  * \param add_len   length of additional data
00127  * \param tag       buffer holding the tag
00128  * \param tag_len   length of the tag
00129  * \param input     buffer holding the input data
00130  * \param output    buffer for holding the output data
00131  *
00132  * \return         0 if successful and authenticated,
00133  *                 MBEDTLS_ERR_GCM_AUTH_FAILED if tag does not match
00134  */
00135 int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
00136                       size_t length,
00137                       const unsigned char *iv,
00138                       size_t iv_len,
00139                       const unsigned char *add,
00140                       size_t add_len,
00141                       const unsigned char *tag,
00142                       size_t tag_len,
00143                       const unsigned char *input,
00144                       unsigned char *output );
00145 
00146 /**
00147  * \brief           Generic GCM stream start function
00148  *
00149  * \param ctx       GCM context
00150  * \param mode      MBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
00151  * \param iv        initialization vector
00152  * \param iv_len    length of IV
00153  * \param add       additional data (or NULL if length is 0)
00154  * \param add_len   length of additional data
00155  *
00156  * \return         0 if successful
00157  */
00158 int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
00159                 int mode,
00160                 const unsigned char *iv,
00161                 size_t iv_len,
00162                 const unsigned char *add,
00163                 size_t add_len );
00164 
00165 /**
00166  * \brief           Generic GCM update function. Encrypts/decrypts using the
00167  *                  given GCM context. Expects input to be a multiple of 16
00168  *                  bytes! Only the last call before mbedtls_gcm_finish() can be less
00169  *                  than 16 bytes!
00170  *
00171  * \note On decryption, the output buffer cannot be the same as input buffer.
00172  *       If buffers overlap, the output buffer must trail at least 8 bytes
00173  *       behind the input buffer.
00174  *
00175  * \param ctx       GCM context
00176  * \param length    length of the input data
00177  * \param input     buffer holding the input data
00178  * \param output    buffer for holding the output data
00179  *
00180  * \return         0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT
00181  */
00182 int mbedtls_gcm_update( mbedtls_gcm_context *ctx,
00183                 size_t length,
00184                 const unsigned char *input,
00185                 unsigned char *output );
00186 
00187 /**
00188  * \brief           Generic GCM finalisation function. Wraps up the GCM stream
00189  *                  and generates the tag. The tag can have a maximum length of
00190  *                  16 bytes.
00191  *
00192  * \param ctx       GCM context
00193  * \param tag       buffer for holding the tag
00194  * \param tag_len   length of the tag to generate (must be at least 4)
00195  *
00196  * \return          0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT
00197  */
00198 int mbedtls_gcm_finish( mbedtls_gcm_context *ctx,
00199                 unsigned char *tag,
00200                 size_t tag_len );
00201 
00202 /**
00203  * \brief           Free a GCM context and underlying cipher sub-context
00204  *
00205  * \param ctx       GCM context to free
00206  */
00207 void mbedtls_gcm_free( mbedtls_gcm_context *ctx );
00208 
00209 /**
00210  * \brief          Checkup routine
00211  *
00212  * \return         0 if successful, or 1 if the test failed
00213  */
00214 int mbedtls_gcm_self_test( int verbose );
00215 
00216 #ifdef __cplusplus
00217 }
00218 #endif
00219 
00220 #endif /* gcm.h */