PolarSSL v1.3.7
Data Structures | Macros | Enumerations | Functions
cipher.h File Reference

Generic cipher wrapper. More...

#include "config.h"
#include <string.h>
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Data Structures

struct  cipher_base_t
 Base cipher information. More...
 
struct  cipher_info_t
 Cipher information. More...
 
struct  cipher_context_t
 Generic cipher context. More...
 

Macros

#define POLARSSL_CIPHER_MODE_AEAD
 
#define POLARSSL_CIPHER_MODE_WITH_PADDING
 
#define POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE   -0x6080
 The selected feature is not available. More...
 
#define POLARSSL_ERR_CIPHER_BAD_INPUT_DATA   -0x6100
 Bad input parameters to function. More...
 
#define POLARSSL_ERR_CIPHER_ALLOC_FAILED   -0x6180
 Failed to allocate memory. More...
 
#define POLARSSL_ERR_CIPHER_INVALID_PADDING   -0x6200
 Input data contains invalid padding and is rejected. More...
 
#define POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED   -0x6280
 Decryption of block requires a full block. More...
 
#define POLARSSL_ERR_CIPHER_AUTH_FAILED   -0x6300
 Authentication failed (for AEAD modes). More...
 
#define POLARSSL_MAX_IV_LENGTH   16
 Maximum length of any IV, in bytes. More...
 
#define POLARSSL_MAX_BLOCK_LENGTH   16
 Maximum block size of any cipher, in bytes. More...
 

Enumerations

enum  cipher_id_t {
  POLARSSL_CIPHER_ID_NONE = 0, POLARSSL_CIPHER_ID_NULL, POLARSSL_CIPHER_ID_AES, POLARSSL_CIPHER_ID_DES,
  POLARSSL_CIPHER_ID_3DES, POLARSSL_CIPHER_ID_CAMELLIA, POLARSSL_CIPHER_ID_BLOWFISH, POLARSSL_CIPHER_ID_ARC4
}
 
enum  cipher_type_t {
  POLARSSL_CIPHER_NONE = 0, POLARSSL_CIPHER_NULL, POLARSSL_CIPHER_AES_128_ECB, POLARSSL_CIPHER_AES_192_ECB,
  POLARSSL_CIPHER_AES_256_ECB, POLARSSL_CIPHER_AES_128_CBC, POLARSSL_CIPHER_AES_192_CBC, POLARSSL_CIPHER_AES_256_CBC,
  POLARSSL_CIPHER_AES_128_CFB128, POLARSSL_CIPHER_AES_192_CFB128, POLARSSL_CIPHER_AES_256_CFB128, POLARSSL_CIPHER_AES_128_CTR,
  POLARSSL_CIPHER_AES_192_CTR, POLARSSL_CIPHER_AES_256_CTR, POLARSSL_CIPHER_AES_128_GCM, POLARSSL_CIPHER_AES_192_GCM,
  POLARSSL_CIPHER_AES_256_GCM, POLARSSL_CIPHER_CAMELLIA_128_ECB, POLARSSL_CIPHER_CAMELLIA_192_ECB, POLARSSL_CIPHER_CAMELLIA_256_ECB,
  POLARSSL_CIPHER_CAMELLIA_128_CBC, POLARSSL_CIPHER_CAMELLIA_192_CBC, POLARSSL_CIPHER_CAMELLIA_256_CBC, POLARSSL_CIPHER_CAMELLIA_128_CFB128,
  POLARSSL_CIPHER_CAMELLIA_192_CFB128, POLARSSL_CIPHER_CAMELLIA_256_CFB128, POLARSSL_CIPHER_CAMELLIA_128_CTR, POLARSSL_CIPHER_CAMELLIA_192_CTR,
  POLARSSL_CIPHER_CAMELLIA_256_CTR, POLARSSL_CIPHER_CAMELLIA_128_GCM, POLARSSL_CIPHER_CAMELLIA_192_GCM, POLARSSL_CIPHER_CAMELLIA_256_GCM,
  POLARSSL_CIPHER_DES_ECB, POLARSSL_CIPHER_DES_CBC, POLARSSL_CIPHER_DES_EDE_ECB, POLARSSL_CIPHER_DES_EDE_CBC,
  POLARSSL_CIPHER_DES_EDE3_ECB, POLARSSL_CIPHER_DES_EDE3_CBC, POLARSSL_CIPHER_BLOWFISH_ECB, POLARSSL_CIPHER_BLOWFISH_CBC,
  POLARSSL_CIPHER_BLOWFISH_CFB64, POLARSSL_CIPHER_BLOWFISH_CTR, POLARSSL_CIPHER_ARC4_128
}
 
enum  cipher_mode_t {
  POLARSSL_MODE_NONE = 0, POLARSSL_MODE_ECB, POLARSSL_MODE_CBC, POLARSSL_MODE_CFB,
  POLARSSL_MODE_OFB, POLARSSL_MODE_CTR, POLARSSL_MODE_GCM, POLARSSL_MODE_STREAM
}
 
enum  cipher_padding_t {
  POLARSSL_PADDING_PKCS7 = 0, POLARSSL_PADDING_ONE_AND_ZEROS, POLARSSL_PADDING_ZEROS_AND_LEN, POLARSSL_PADDING_ZEROS,
  POLARSSL_PADDING_NONE
}
 
enum  operation_t { POLARSSL_OPERATION_NONE = -1, POLARSSL_DECRYPT = 0, POLARSSL_ENCRYPT }
 
enum  { POLARSSL_KEY_LENGTH_NONE = 0, POLARSSL_KEY_LENGTH_DES = 64, POLARSSL_KEY_LENGTH_DES_EDE = 128, POLARSSL_KEY_LENGTH_DES_EDE3 = 192 }
 

Functions

const int * cipher_list (void)
 Returns the list of ciphers supported by the generic cipher module. More...
 
const cipher_info_tcipher_info_from_string (const char *cipher_name)
 Returns the cipher information structure associated with the given cipher name. More...
 
const cipher_info_tcipher_info_from_type (const cipher_type_t cipher_type)
 Returns the cipher information structure associated with the given cipher type. More...
 
const cipher_info_tcipher_info_from_values (const cipher_id_t cipher_id, int key_length, const cipher_mode_t mode)
 Returns the cipher information structure associated with the given cipher id, key size and mode. More...
 
int cipher_init_ctx (cipher_context_t *ctx, const cipher_info_t *cipher_info)
 Initialises and fills the cipher context structure with the appropriate values. More...
 
int cipher_free_ctx (cipher_context_t *ctx)
 Free the cipher-specific context of ctx. More...
 
static unsigned int cipher_get_block_size (const cipher_context_t *ctx)
 Returns the block size of the given cipher. More...
 
static cipher_mode_t cipher_get_cipher_mode (const cipher_context_t *ctx)
 Returns the mode of operation for the cipher. More...
 
static int cipher_get_iv_size (const cipher_context_t *ctx)
 Returns the size of the cipher's IV/NONCE in bytes. More...
 
static cipher_type_t cipher_get_type (const cipher_context_t *ctx)
 Returns the type of the given cipher. More...
 
static const char * cipher_get_name (const cipher_context_t *ctx)
 Returns the name of the given cipher, as a string. More...
 
static int cipher_get_key_size (const cipher_context_t *ctx)
 Returns the key length of the cipher. More...
 
static operation_t cipher_get_operation (const cipher_context_t *ctx)
 Returns the operation of the given cipher. More...
 
int cipher_setkey (cipher_context_t *ctx, const unsigned char *key, int key_length, const operation_t operation)
 Set the key to use with the given context. More...
 
int cipher_set_padding_mode (cipher_context_t *ctx, cipher_padding_t mode)
 Set padding mode, for cipher modes that use padding. More...
 
int cipher_set_iv (cipher_context_t *ctx, const unsigned char *iv, size_t iv_len)
 Set the initialization vector (IV) or nonce. More...
 
int cipher_reset (cipher_context_t *ctx)
 Finish preparation of the given context. More...
 
int cipher_update_ad (cipher_context_t *ctx, const unsigned char *ad, size_t ad_len)
 Add additional data (for AEAD ciphers). More...
 
int cipher_update (cipher_context_t *ctx, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen)
 Generic cipher update function. More...
 
int cipher_finish (cipher_context_t *ctx, unsigned char *output, size_t *olen)
 Generic cipher finalisation function. More...
 
int cipher_write_tag (cipher_context_t *ctx, unsigned char *tag, size_t tag_len)
 Write tag for AEAD ciphers. More...
 
int cipher_check_tag (cipher_context_t *ctx, const unsigned char *tag, size_t tag_len)
 Check tag for AEAD ciphers. More...
 
int cipher_self_test (int verbose)
 Checkup routine. More...
 

Detailed Description

Generic cipher wrapper.

Author
Adriaan de Jong dejon.nosp@m.g@fo.nosp@m.x-it..nosp@m.com

Copyright (C) 2006-2014, 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.

Definition in file cipher.h.

Macro Definition Documentation

#define POLARSSL_CIPHER_MODE_AEAD

Definition at line 40 of file cipher.h.

#define POLARSSL_CIPHER_MODE_WITH_PADDING

Definition at line 44 of file cipher.h.

#define POLARSSL_ERR_CIPHER_ALLOC_FAILED   -0x6180

Failed to allocate memory.

Definition at line 59 of file cipher.h.

#define POLARSSL_ERR_CIPHER_AUTH_FAILED   -0x6300

Authentication failed (for AEAD modes).

Definition at line 62 of file cipher.h.

#define POLARSSL_ERR_CIPHER_BAD_INPUT_DATA   -0x6100

Bad input parameters to function.

Definition at line 58 of file cipher.h.

#define POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE   -0x6080

The selected feature is not available.

Definition at line 57 of file cipher.h.

#define POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED   -0x6280

Decryption of block requires a full block.

Definition at line 61 of file cipher.h.

#define POLARSSL_ERR_CIPHER_INVALID_PADDING   -0x6200

Input data contains invalid padding and is rejected.

Definition at line 60 of file cipher.h.

#define POLARSSL_MAX_BLOCK_LENGTH   16

Maximum block size of any cipher, in bytes.

Definition at line 164 of file cipher.h.

#define POLARSSL_MAX_IV_LENGTH   16

Maximum length of any IV, in bytes.

Definition at line 162 of file cipher.h.

Enumeration Type Documentation

anonymous enum
Enumerator
POLARSSL_KEY_LENGTH_NONE 

Undefined key length.

POLARSSL_KEY_LENGTH_DES 

Key length, in bits (including parity), for DES keys.

POLARSSL_KEY_LENGTH_DES_EDE 

Key length, in bits (including parity), for DES in two key EDE.

POLARSSL_KEY_LENGTH_DES_EDE3 

Key length, in bits (including parity), for DES in three-key EDE.

Definition at line 150 of file cipher.h.

Enumerator
POLARSSL_CIPHER_ID_NONE 
POLARSSL_CIPHER_ID_NULL 
POLARSSL_CIPHER_ID_AES 
POLARSSL_CIPHER_ID_DES 
POLARSSL_CIPHER_ID_3DES 
POLARSSL_CIPHER_ID_CAMELLIA 
POLARSSL_CIPHER_ID_BLOWFISH 
POLARSSL_CIPHER_ID_ARC4 

Definition at line 68 of file cipher.h.

Enumerator
POLARSSL_MODE_NONE 
POLARSSL_MODE_ECB 
POLARSSL_MODE_CBC 
POLARSSL_MODE_CFB 
POLARSSL_MODE_OFB 
POLARSSL_MODE_CTR 
POLARSSL_MODE_GCM 
POLARSSL_MODE_STREAM 

Definition at line 125 of file cipher.h.

Enumerator
POLARSSL_PADDING_PKCS7 

PKCS7 padding (default)

POLARSSL_PADDING_ONE_AND_ZEROS 

ISO/IEC 7816-4 padding.

POLARSSL_PADDING_ZEROS_AND_LEN 

ANSI X.923 padding.

POLARSSL_PADDING_ZEROS 

zero padding (not reversible!)

POLARSSL_PADDING_NONE 

never pad (full blocks only)

Definition at line 136 of file cipher.h.

Enumerator
POLARSSL_CIPHER_NONE 
POLARSSL_CIPHER_NULL 
POLARSSL_CIPHER_AES_128_ECB 
POLARSSL_CIPHER_AES_192_ECB 
POLARSSL_CIPHER_AES_256_ECB 
POLARSSL_CIPHER_AES_128_CBC 
POLARSSL_CIPHER_AES_192_CBC 
POLARSSL_CIPHER_AES_256_CBC 
POLARSSL_CIPHER_AES_128_CFB128 
POLARSSL_CIPHER_AES_192_CFB128 
POLARSSL_CIPHER_AES_256_CFB128 
POLARSSL_CIPHER_AES_128_CTR 
POLARSSL_CIPHER_AES_192_CTR 
POLARSSL_CIPHER_AES_256_CTR 
POLARSSL_CIPHER_AES_128_GCM 
POLARSSL_CIPHER_AES_192_GCM 
POLARSSL_CIPHER_AES_256_GCM 
POLARSSL_CIPHER_CAMELLIA_128_ECB 
POLARSSL_CIPHER_CAMELLIA_192_ECB 
POLARSSL_CIPHER_CAMELLIA_256_ECB 
POLARSSL_CIPHER_CAMELLIA_128_CBC 
POLARSSL_CIPHER_CAMELLIA_192_CBC 
POLARSSL_CIPHER_CAMELLIA_256_CBC 
POLARSSL_CIPHER_CAMELLIA_128_CFB128 
POLARSSL_CIPHER_CAMELLIA_192_CFB128 
POLARSSL_CIPHER_CAMELLIA_256_CFB128 
POLARSSL_CIPHER_CAMELLIA_128_CTR 
POLARSSL_CIPHER_CAMELLIA_192_CTR 
POLARSSL_CIPHER_CAMELLIA_256_CTR 
POLARSSL_CIPHER_CAMELLIA_128_GCM 
POLARSSL_CIPHER_CAMELLIA_192_GCM 
POLARSSL_CIPHER_CAMELLIA_256_GCM 
POLARSSL_CIPHER_DES_ECB 
POLARSSL_CIPHER_DES_CBC 
POLARSSL_CIPHER_DES_EDE_ECB 
POLARSSL_CIPHER_DES_EDE_CBC 
POLARSSL_CIPHER_DES_EDE3_ECB 
POLARSSL_CIPHER_DES_EDE3_CBC 
POLARSSL_CIPHER_BLOWFISH_ECB 
POLARSSL_CIPHER_BLOWFISH_CBC 
POLARSSL_CIPHER_BLOWFISH_CFB64 
POLARSSL_CIPHER_BLOWFISH_CTR 
POLARSSL_CIPHER_ARC4_128 

Definition at line 79 of file cipher.h.

Enumerator
POLARSSL_OPERATION_NONE 
POLARSSL_DECRYPT 
POLARSSL_ENCRYPT 

Definition at line 144 of file cipher.h.

Function Documentation

int cipher_check_tag ( cipher_context_t ctx,
const unsigned char *  tag,
size_t  tag_len 
)

Check tag for AEAD ciphers.

                 No effect for other ciphers.
                 Calling time depends on the cipher:
                 for GCM, must be called after cipher_finish().
Parameters
ctxGeneric cipher context
tagBuffer holding the tag
tag_lenLength of the tag to check
Returns
0 on success, or a specific error code.
int cipher_finish ( cipher_context_t ctx,
unsigned char *  output,
size_t *  olen 
)

Generic cipher finalisation function.

If data still needs to be flushed from an incomplete block, data contained within it will be padded with the size of the last block, and written to the output buffer.

Parameters
ctxGeneric cipher context
outputbuffer to write data to. Needs block_size available.
olenlength of the data written to the output buffer.
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails, POLARSSL_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption expected a full block but was not provided one, POLARSSL_ERR_CIPHER_INVALID_PADDING on invalid padding while decrypting or a cipher specific error code.
int cipher_free_ctx ( cipher_context_t ctx)

Free the cipher-specific context of ctx.

Freeing ctx itself remains the responsibility of the caller.

Parameters
ctxFree the cipher-specific context
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails.
static unsigned int cipher_get_block_size ( const cipher_context_t ctx)
inlinestatic

Returns the block size of the given cipher.

Parameters
ctxcipher's context. Must have been initialised.
Returns
size of the cipher's blocks, or 0 if ctx has not been initialised.

Definition at line 357 of file cipher.h.

References cipher_info_t::block_size, and cipher_context_t::cipher_info.

static cipher_mode_t cipher_get_cipher_mode ( const cipher_context_t ctx)
inlinestatic

Returns the mode of operation for the cipher.

                 (e.g. POLARSSL_MODE_CBC)
Parameters
ctxcipher's context. Must have been initialised.
Returns
mode of operation, or POLARSSL_MODE_NONE if ctx has not been initialised.

Definition at line 374 of file cipher.h.

References cipher_context_t::cipher_info, cipher_info_t::mode, and POLARSSL_MODE_NONE.

static int cipher_get_iv_size ( const cipher_context_t ctx)
inlinestatic

Returns the size of the cipher's IV/NONCE in bytes.

Parameters
ctxcipher's context. Must have been initialised.
Returns
If IV has not been set yet: (recommended) IV size (0 for ciphers not using IV/NONCE). If IV has already been set: actual size.

Definition at line 391 of file cipher.h.

References cipher_context_t::cipher_info, cipher_info_t::iv_size, and cipher_context_t::iv_size.

static int cipher_get_key_size ( const cipher_context_t ctx)
inlinestatic

Returns the key length of the cipher.

Parameters
ctxcipher's context. Must have been initialised.
Returns
cipher's key length, in bits, or POLARSSL_KEY_LENGTH_NONE if ctx has not been initialised.

Definition at line 442 of file cipher.h.

References cipher_context_t::cipher_info, cipher_info_t::key_length, and POLARSSL_KEY_LENGTH_NONE.

static const char* cipher_get_name ( const cipher_context_t ctx)
inlinestatic

Returns the name of the given cipher, as a string.

Parameters
ctxcipher's context. Must have been initialised.
Returns
name of the cipher, or NULL if ctx was not initialised.

Definition at line 425 of file cipher.h.

References cipher_context_t::cipher_info, and cipher_info_t::name.

static operation_t cipher_get_operation ( const cipher_context_t ctx)
inlinestatic

Returns the operation of the given cipher.

Parameters
ctxcipher's context. Must have been initialised.
Returns
operation (POLARSSL_ENCRYPT or POLARSSL_DECRYPT), or POLARSSL_OPERATION_NONE if ctx has not been initialised.

Definition at line 459 of file cipher.h.

References cipher_context_t::cipher_info, cipher_context_t::operation, and POLARSSL_OPERATION_NONE.

static cipher_type_t cipher_get_type ( const cipher_context_t ctx)
inlinestatic

Returns the type of the given cipher.

Parameters
ctxcipher's context. Must have been initialised.
Returns
type of the cipher, or POLARSSL_CIPHER_NONE if ctx has not been initialised.

Definition at line 410 of file cipher.h.

References cipher_context_t::cipher_info, POLARSSL_CIPHER_NONE, and cipher_info_t::type.

const cipher_info_t* cipher_info_from_string ( const char *  cipher_name)

Returns the cipher information structure associated with the given cipher name.

Parameters
cipher_nameName of the cipher to search for.
Returns
the cipher information structure associated with the given cipher_name, or NULL if not found.
const cipher_info_t* cipher_info_from_type ( const cipher_type_t  cipher_type)

Returns the cipher information structure associated with the given cipher type.

Parameters
cipher_typeType of the cipher to search for.
Returns
the cipher information structure associated with the given cipher_type, or NULL if not found.
const cipher_info_t* cipher_info_from_values ( const cipher_id_t  cipher_id,
int  key_length,
const cipher_mode_t  mode 
)

Returns the cipher information structure associated with the given cipher id, key size and mode.

Parameters
cipher_idId of the cipher to search for (e.g. POLARSSL_CIPHER_ID_AES)
key_lengthLength of the key in bits
modeCipher mode (e.g. POLARSSL_MODE_CBC)
Returns
the cipher information structure associated with the given cipher_type, or NULL if not found.
int cipher_init_ctx ( cipher_context_t ctx,
const cipher_info_t cipher_info 
)

Initialises and fills the cipher context structure with the appropriate values.

Parameters
ctxcontext to initialise. May not be NULL.
cipher_infocipher to use.
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA on parameter failure, POLARSSL_ERR_CIPHER_ALLOC_FAILED if allocation of the cipher-specific context failed.
const int* cipher_list ( void  )

Returns the list of ciphers supported by the generic cipher module.

Returns
a statically allocated array of ciphers, the last entry is 0.
int cipher_reset ( cipher_context_t ctx)

Finish preparation of the given context.

Parameters
ctxgeneric cipher context
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails.
int cipher_self_test ( int  verbose)

Checkup routine.

Returns
0 if successful, or 1 if the test failed
int cipher_set_iv ( cipher_context_t ctx,
const unsigned char *  iv,
size_t  iv_len 
)

Set the initialization vector (IV) or nonce.

Parameters
ctxgeneric cipher context
ivIV to use (or NONCE_COUNTER for CTR-mode ciphers)
iv_lenIV length for ciphers with variable-size IV; discarded by ciphers with fixed-size IV.
Returns
O on success, or POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
Note
Some ciphers don't use IVs nor NONCE. For these ciphers, this function has no effect.
int cipher_set_padding_mode ( cipher_context_t ctx,
cipher_padding_t  mode 
)

Set padding mode, for cipher modes that use padding.

                 (Default: PKCS7 padding.)
Parameters
ctxgeneric cipher context
modepadding mode
Returns
0 on success, POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE if selected padding mode is not supported, or POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode does not support padding.
int cipher_setkey ( cipher_context_t ctx,
const unsigned char *  key,
int  key_length,
const operation_t  operation 
)

Set the key to use with the given context.

Parameters
ctxgeneric cipher context. May not be NULL. Must have been initialised using cipher_context_from_type or cipher_context_from_string.
keyThe key to use.
key_lengthkey length to use, in bits.
operationOperation that the key will be used for, either POLARSSL_ENCRYPT or POLARSSL_DECRYPT.
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails or a cipher specific error code.
int cipher_update ( cipher_context_t ctx,
const unsigned char *  input,
size_t  ilen,
unsigned char *  output,
size_t *  olen 
)

Generic cipher update function.

Encrypts/decrypts using the given cipher context. Writes as many block size'd blocks of data as possible to output. Any data that cannot be written immediately will either be added to the next block, or flushed when cipher_final is called. Exception: for POLARSSL_MODE_ECB, expects single block in size (e.g. 16 bytes for AES)

Parameters
ctxgeneric cipher context
inputbuffer holding the input data
ilenlength of the input data
outputbuffer for the output data. Should be able to hold at least ilen + block_size. Cannot be the same buffer as input!
olenlength of the output data, will be filled with the actual number of bytes written.
Returns
0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails, POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE on an unsupported mode for a cipher or a cipher specific error code.
Note
If the underlying cipher is GCM, all calls to this function, except the last one before cipher_finish(), must have ilen a multiple of the block size.
int cipher_update_ad ( cipher_context_t ctx,
const unsigned char *  ad,
size_t  ad_len 
)

Add additional data (for AEAD ciphers).

                 This function has no effect for non-AEAD ciphers.
                 For AEAD ciphers, it may or may not be called
                 repeatedly, and/or interleaved with calls to
                 cipher_udpate(), depending on the cipher.
                 E.g. for GCM is must be called exactly once, right
                 after cipher_reset().
Parameters
ctxgeneric cipher context
adAdditional data to use.
ad_lenLength of ad.
Returns
0 on success, or a specific error code.
int cipher_write_tag ( cipher_context_t ctx,
unsigned char *  tag,
size_t  tag_len 
)

Write tag for AEAD ciphers.

                 No effect for other ciphers.
                 Must be called after cipher_finish().
Parameters
ctxGeneric cipher context
tagbuffer to write the tag
tag_lenLength of the tag to write
Returns
0 on success, or a specific error code.