mbed TLS v2.2.0
Data Structures | Macros | Functions
gcm.h File Reference

Detailed Description

Galois/Counter mode for 128-bit block ciphers.

Copyright (C) 2006-2015, ARM Limited, 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)

Definition in file gcm.h.

#include "cipher.h"
#include <stdint.h>
Include dependency graph for gcm.h:

Go to the source code of this file.

Data Structures

struct  mbedtls_gcm_context
 GCM context structure. More...
 

Macros

#define MBEDTLS_GCM_ENCRYPT   1
 
#define MBEDTLS_GCM_DECRYPT   0
 
#define MBEDTLS_ERR_GCM_AUTH_FAILED   -0x0012
 Authenticated decryption failed. More...
 
#define MBEDTLS_ERR_GCM_BAD_INPUT   -0x0014
 Bad input parameters to function. More...
 

Functions

void mbedtls_gcm_init (mbedtls_gcm_context *ctx)
 Initialize GCM context (just makes references valid) Makes the context ready for mbedtls_gcm_setkey() or mbedtls_gcm_free(). More...
 
int mbedtls_gcm_setkey (mbedtls_gcm_context *ctx, mbedtls_cipher_id_t cipher, const unsigned char *key, unsigned int keybits)
 GCM initialization (encryption) More...
 
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)
 GCM buffer encryption/decryption using a block cipher. More...
 
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)
 GCM buffer authenticated decryption using a block cipher. More...
 
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)
 Generic GCM stream start function. More...
 
int mbedtls_gcm_update (mbedtls_gcm_context *ctx, size_t length, const unsigned char *input, unsigned char *output)
 Generic GCM update function. More...
 
int mbedtls_gcm_finish (mbedtls_gcm_context *ctx, unsigned char *tag, size_t tag_len)
 Generic GCM finalisation function. More...
 
void mbedtls_gcm_free (mbedtls_gcm_context *ctx)
 Free a GCM context and underlying cipher sub-context. More...
 
int mbedtls_gcm_self_test (int verbose)
 Checkup routine. More...
 

Macro Definition Documentation

#define MBEDTLS_ERR_GCM_AUTH_FAILED   -0x0012

Authenticated decryption failed.

Definition at line 33 of file gcm.h.

#define MBEDTLS_ERR_GCM_BAD_INPUT   -0x0014

Bad input parameters to function.

Definition at line 34 of file gcm.h.

#define MBEDTLS_GCM_DECRYPT   0

Definition at line 31 of file gcm.h.

#define MBEDTLS_GCM_ENCRYPT   1

Definition at line 30 of file gcm.h.

Function Documentation

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 
)

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.
Parameters
ctxGCM context
lengthlength of the input data
ivinitialization vector
iv_lenlength of IV
addadditional data
add_lenlength of additional data
tagbuffer holding the tag
tag_lenlength of the tag
inputbuffer holding the input data
outputbuffer for holding the output data
Returns
0 if successful and authenticated, MBEDTLS_ERR_GCM_AUTH_FAILED if tag does not match
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 
)

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.
Parameters
ctxGCM context
modeMBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
lengthlength of the input data
ivinitialization vector
iv_lenlength of IV
addadditional data
add_lenlength of additional data
inputbuffer holding the input data
outputbuffer for holding the output data
tag_lenlength of the tag to generate
tagbuffer for holding the tag
Returns
0 if successful
int mbedtls_gcm_finish ( mbedtls_gcm_context ctx,
unsigned char *  tag,
size_t  tag_len 
)

Generic GCM finalisation function.

Wraps up the GCM stream and generates the tag. The tag can have a maximum length of 16 bytes.

Parameters
ctxGCM context
tagbuffer for holding the tag (may be NULL if tag_len is 0)
tag_lenlength of the tag to generate
Returns
0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT
void mbedtls_gcm_free ( mbedtls_gcm_context ctx)

Free a GCM context and underlying cipher sub-context.

Parameters
ctxGCM context to free
void mbedtls_gcm_init ( mbedtls_gcm_context ctx)

Initialize GCM context (just makes references valid) Makes the context ready for mbedtls_gcm_setkey() or mbedtls_gcm_free().

Parameters
ctxGCM context to initialize
int mbedtls_gcm_self_test ( int  verbose)

Checkup routine.

Returns
0 if successful, or 1 if the test failed
int mbedtls_gcm_setkey ( mbedtls_gcm_context ctx,
mbedtls_cipher_id_t  cipher,
const unsigned char *  key,
unsigned int  keybits 
)

GCM initialization (encryption)

Parameters
ctxGCM context to be initialized
ciphercipher to use (a 128-bit block cipher)
keyencryption key
keybitsmust be 128, 192 or 256
Returns
0 if successful, or a cipher specific error code
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 
)

Generic GCM stream start function.

Parameters
ctxGCM context
modeMBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
ivinitialization vector
iv_lenlength of IV
addadditional data (or NULL if length is 0)
add_lenlength of additional data
Returns
0 if successful
int mbedtls_gcm_update ( mbedtls_gcm_context ctx,
size_t  length,
const unsigned char *  input,
unsigned char *  output 
)

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 mbedtls_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.
Parameters
ctxGCM context
lengthlength of the input data
inputbuffer holding the input data
outputbuffer for holding the output data
Returns
0 if successful or MBEDTLS_ERR_GCM_BAD_INPUT