mbed TLS  Version 2.8.0
SSL/TLS Library for the Embedded Space
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cipher.h File Reference

Data Structures

struct  mbedtls_cipher_info_t
 Cipher information. More...
 
struct  mbedtls_cipher_context_t
 Generic cipher context. More...
 

Macros

#define MBEDTLS_CIPHER_MODE_AEAD
 
#define MBEDTLS_CIPHER_MODE_WITH_PADDING
 
#define MBEDTLS_CIPHER_MODE_STREAM
 
#define MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE   -0x6080
 The selected feature is not available. More...
 
#define MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA   -0x6100
 Bad input parameters. More...
 
#define MBEDTLS_ERR_CIPHER_ALLOC_FAILED   -0x6180
 Failed to allocate memory. More...
 
#define MBEDTLS_ERR_CIPHER_INVALID_PADDING   -0x6200
 Input data contains invalid padding and is rejected. More...
 
#define MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED   -0x6280
 Decryption of block requires a full block. More...
 
#define MBEDTLS_ERR_CIPHER_AUTH_FAILED   -0x6300
 Authentication failed (for AEAD modes). More...
 
#define MBEDTLS_ERR_CIPHER_INVALID_CONTEXT   -0x6380
 The context is invalid. More...
 
#define MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED   -0x6400
 Cipher hardware accelerator failed. More...
 
#define MBEDTLS_CIPHER_VARIABLE_IV_LEN   0x01
 Cipher accepts IVs of variable length. More...
 
#define MBEDTLS_CIPHER_VARIABLE_KEY_LEN   0x02
 Cipher accepts keys of variable length. More...
 
#define MBEDTLS_MAX_IV_LENGTH   16
 Maximum length of any IV, in Bytes. More...
 
#define MBEDTLS_MAX_BLOCK_LENGTH   16
 Maximum block size of any cipher, in Bytes. More...
 

Enumerations

enum  mbedtls_cipher_id_t {
  MBEDTLS_CIPHER_ID_NONE = 0,
  MBEDTLS_CIPHER_ID_NULL,
  MBEDTLS_CIPHER_ID_AES,
  MBEDTLS_CIPHER_ID_DES,
  MBEDTLS_CIPHER_ID_3DES,
  MBEDTLS_CIPHER_ID_CAMELLIA,
  MBEDTLS_CIPHER_ID_BLOWFISH,
  MBEDTLS_CIPHER_ID_ARC4
}
 An enumeration of supported ciphers. More...
 
enum  mbedtls_cipher_type_t {
  MBEDTLS_CIPHER_NONE = 0,
  MBEDTLS_CIPHER_NULL,
  MBEDTLS_CIPHER_AES_128_ECB,
  MBEDTLS_CIPHER_AES_192_ECB,
  MBEDTLS_CIPHER_AES_256_ECB,
  MBEDTLS_CIPHER_AES_128_CBC,
  MBEDTLS_CIPHER_AES_192_CBC,
  MBEDTLS_CIPHER_AES_256_CBC,
  MBEDTLS_CIPHER_AES_128_CFB128,
  MBEDTLS_CIPHER_AES_192_CFB128,
  MBEDTLS_CIPHER_AES_256_CFB128,
  MBEDTLS_CIPHER_AES_128_CTR,
  MBEDTLS_CIPHER_AES_192_CTR,
  MBEDTLS_CIPHER_AES_256_CTR,
  MBEDTLS_CIPHER_AES_128_GCM,
  MBEDTLS_CIPHER_AES_192_GCM,
  MBEDTLS_CIPHER_AES_256_GCM,
  MBEDTLS_CIPHER_CAMELLIA_128_ECB,
  MBEDTLS_CIPHER_CAMELLIA_192_ECB,
  MBEDTLS_CIPHER_CAMELLIA_256_ECB,
  MBEDTLS_CIPHER_CAMELLIA_128_CBC,
  MBEDTLS_CIPHER_CAMELLIA_192_CBC,
  MBEDTLS_CIPHER_CAMELLIA_256_CBC,
  MBEDTLS_CIPHER_CAMELLIA_128_CFB128,
  MBEDTLS_CIPHER_CAMELLIA_192_CFB128,
  MBEDTLS_CIPHER_CAMELLIA_256_CFB128,
  MBEDTLS_CIPHER_CAMELLIA_128_CTR,
  MBEDTLS_CIPHER_CAMELLIA_192_CTR,
  MBEDTLS_CIPHER_CAMELLIA_256_CTR,
  MBEDTLS_CIPHER_CAMELLIA_128_GCM,
  MBEDTLS_CIPHER_CAMELLIA_192_GCM,
  MBEDTLS_CIPHER_CAMELLIA_256_GCM,
  MBEDTLS_CIPHER_DES_ECB,
  MBEDTLS_CIPHER_DES_CBC,
  MBEDTLS_CIPHER_DES_EDE_ECB,
  MBEDTLS_CIPHER_DES_EDE_CBC,
  MBEDTLS_CIPHER_DES_EDE3_ECB,
  MBEDTLS_CIPHER_DES_EDE3_CBC,
  MBEDTLS_CIPHER_BLOWFISH_ECB,
  MBEDTLS_CIPHER_BLOWFISH_CBC,
  MBEDTLS_CIPHER_BLOWFISH_CFB64,
  MBEDTLS_CIPHER_BLOWFISH_CTR,
  MBEDTLS_CIPHER_ARC4_128,
  MBEDTLS_CIPHER_AES_128_CCM,
  MBEDTLS_CIPHER_AES_192_CCM,
  MBEDTLS_CIPHER_AES_256_CCM,
  MBEDTLS_CIPHER_CAMELLIA_128_CCM,
  MBEDTLS_CIPHER_CAMELLIA_192_CCM,
  MBEDTLS_CIPHER_CAMELLIA_256_CCM
}
 An enumeration of supported (cipher, mode) pairs. More...
 
enum  mbedtls_cipher_mode_t {
  MBEDTLS_MODE_NONE = 0,
  MBEDTLS_MODE_ECB,
  MBEDTLS_MODE_CBC,
  MBEDTLS_MODE_CFB,
  MBEDTLS_MODE_OFB,
  MBEDTLS_MODE_CTR,
  MBEDTLS_MODE_GCM,
  MBEDTLS_MODE_STREAM,
  MBEDTLS_MODE_CCM
}
 Supported cipher modes. More...
 
enum  mbedtls_cipher_padding_t {
  MBEDTLS_PADDING_PKCS7 = 0,
  MBEDTLS_PADDING_ONE_AND_ZEROS,
  MBEDTLS_PADDING_ZEROS_AND_LEN,
  MBEDTLS_PADDING_ZEROS,
  MBEDTLS_PADDING_NONE
}
 Supported cipher padding types. More...
 
enum  mbedtls_operation_t {
  MBEDTLS_OPERATION_NONE = -1,
  MBEDTLS_DECRYPT = 0,
  MBEDTLS_ENCRYPT
}
 Type of operation. More...
 
enum  {
  MBEDTLS_KEY_LENGTH_NONE = 0,
  MBEDTLS_KEY_LENGTH_DES = 64,
  MBEDTLS_KEY_LENGTH_DES_EDE = 128,
  MBEDTLS_KEY_LENGTH_DES_EDE3 = 192
}
 

Functions

const int * mbedtls_cipher_list (void)
 This function retrieves the list of ciphers supported by the generic cipher module. More...
 
const mbedtls_cipher_info_tmbedtls_cipher_info_from_string (const char *cipher_name)
 This function retrieves the cipher-information structure associated with the given cipher name. More...
 
const mbedtls_cipher_info_tmbedtls_cipher_info_from_type (const mbedtls_cipher_type_t cipher_type)
 This function retrieves the cipher-information structure associated with the given cipher type. More...
 
const mbedtls_cipher_info_tmbedtls_cipher_info_from_values (const mbedtls_cipher_id_t cipher_id, int key_bitlen, const mbedtls_cipher_mode_t mode)
 This function retrieves the cipher-information structure associated with the given cipher ID, key size and mode. More...
 
void mbedtls_cipher_init (mbedtls_cipher_context_t *ctx)
 This function initializes a cipher_context as NONE.
 
void mbedtls_cipher_free (mbedtls_cipher_context_t *ctx)
 This function frees and clears the cipher-specific context of ctx. More...
 
int mbedtls_cipher_setup (mbedtls_cipher_context_t *ctx, const mbedtls_cipher_info_t *cipher_info)
 This function initializes and fills the cipher-context structure with the appropriate values. More...
 
int mbedtls_cipher_setkey (mbedtls_cipher_context_t *ctx, const unsigned char *key, int key_bitlen, const mbedtls_operation_t operation)
 This function sets the key to use with the given context. More...
 
int mbedtls_cipher_set_padding_mode (mbedtls_cipher_context_t *ctx, mbedtls_cipher_padding_t mode)
 This function sets the padding mode, for cipher modes that use padding. More...
 
int mbedtls_cipher_set_iv (mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len)
 This function sets the initialization vector (IV) or nonce. More...
 
int mbedtls_cipher_reset (mbedtls_cipher_context_t *ctx)
 This function resets the cipher state. More...
 
int mbedtls_cipher_update_ad (mbedtls_cipher_context_t *ctx, const unsigned char *ad, size_t ad_len)
 This function adds additional data for AEAD ciphers. More...
 
int mbedtls_cipher_update (mbedtls_cipher_context_t *ctx, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen)
 The generic cipher update function. More...
 
int mbedtls_cipher_finish (mbedtls_cipher_context_t *ctx, unsigned char *output, size_t *olen)
 The generic cipher finalization function. More...
 
int mbedtls_cipher_write_tag (mbedtls_cipher_context_t *ctx, unsigned char *tag, size_t tag_len)
 This function writes a tag for AEAD ciphers. More...
 
int mbedtls_cipher_check_tag (mbedtls_cipher_context_t *ctx, const unsigned char *tag, size_t tag_len)
 This function checks the tag for AEAD ciphers. More...
 
int mbedtls_cipher_crypt (mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen)
 The generic all-in-one encryption/decryption function, for all ciphers except AEAD constructs. More...
 
int mbedtls_cipher_auth_encrypt (mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *ad, size_t ad_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen, unsigned char *tag, size_t tag_len)
 The generic autenticated encryption (AEAD) function. More...
 
int mbedtls_cipher_auth_decrypt (mbedtls_cipher_context_t *ctx, const unsigned char *iv, size_t iv_len, const unsigned char *ad, size_t ad_len, const unsigned char *input, size_t ilen, unsigned char *output, size_t *olen, const unsigned char *tag, size_t tag_len)
 The generic autenticated decryption (AEAD) function. More...
 

Description

The generic cipher wrapper.

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

Data Structure Documentation

struct mbedtls_cipher_info_t

Cipher information.

Allows calling cipher functions in a generic way.

Data Fields
const mbedtls_cipher_base_t * base Struct for base cipher information and functions.
unsigned int block_size The block size, in Bytes.
int flags Flags to set.

For example, if the cipher supports variable IV sizes or variable key sizes.

unsigned int iv_size IV or nonce size, in Bytes.

For ciphers that accept variable IV sizes, this is the recommended size.

unsigned int key_bitlen The cipher key length, in bits.

This is the default length for variable sized ciphers. Includes parity bits for ciphers like DES.

mbedtls_cipher_mode_t mode The cipher mode.

For example, MBEDTLS_MODE_CBC.

const char * name Name of the cipher.
mbedtls_cipher_type_t type Full cipher identifier.

For example, MBEDTLS_CIPHER_AES_256_CBC.

Macro Definition Documentation

#define MBEDTLS_CIPHER_VARIABLE_IV_LEN   0x01

Cipher accepts IVs of variable length.

#define MBEDTLS_CIPHER_VARIABLE_KEY_LEN   0x02

Cipher accepts keys of variable length.

#define MBEDTLS_ERR_CIPHER_ALLOC_FAILED   -0x6180

Failed to allocate memory.

#define MBEDTLS_ERR_CIPHER_AUTH_FAILED   -0x6300

Authentication failed (for AEAD modes).

#define MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA   -0x6100

Bad input parameters.

#define MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE   -0x6080

The selected feature is not available.

#define MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED   -0x6280

Decryption of block requires a full block.

#define MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED   -0x6400

Cipher hardware accelerator failed.

#define MBEDTLS_ERR_CIPHER_INVALID_CONTEXT   -0x6380

The context is invalid.

For example, because it was freed.

#define MBEDTLS_ERR_CIPHER_INVALID_PADDING   -0x6200

Input data contains invalid padding and is rejected.

#define MBEDTLS_MAX_BLOCK_LENGTH   16

Maximum block size of any cipher, in Bytes.

#define MBEDTLS_MAX_IV_LENGTH   16

Maximum length of any IV, in Bytes.

Enumeration Type Documentation

anonymous enum
Enumerator
MBEDTLS_KEY_LENGTH_NONE 

Undefined key length.

MBEDTLS_KEY_LENGTH_DES 

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

MBEDTLS_KEY_LENGTH_DES_EDE 

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

MBEDTLS_KEY_LENGTH_DES_EDE3 

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

An enumeration of supported ciphers.

Warning
ARC4 and DES are considered weak ciphers and their use constitutes a security risk. We recommend considering stronger ciphers instead.

Supported cipher modes.

Supported cipher padding types.

Enumerator
MBEDTLS_PADDING_PKCS7 

PKCS7 padding (default).

MBEDTLS_PADDING_ONE_AND_ZEROS 

ISO/IEC 7816-4 padding.

MBEDTLS_PADDING_ZEROS_AND_LEN 

ANSI X.923 padding.

MBEDTLS_PADDING_ZEROS 

zero padding (not reversible).

MBEDTLS_PADDING_NONE 

never pad (full blocks only).

An enumeration of supported (cipher, mode) pairs.

Warning
ARC4 and DES are considered weak ciphers and their use constitutes a security risk. We recommend considering stronger ciphers instead.

Type of operation.

Function Documentation

int mbedtls_cipher_auth_decrypt ( mbedtls_cipher_context_t ctx,
const unsigned char *  iv,
size_t  iv_len,
const unsigned char *  ad,
size_t  ad_len,
const unsigned char *  input,
size_t  ilen,
unsigned char *  output,
size_t *  olen,
const unsigned char *  tag,
size_t  tag_len 
)

The generic autenticated decryption (AEAD) function.

Parameters
ctxThe generic cipher context.
ivThe IV to use, or NONCE_COUNTER for CTR-mode ciphers.
iv_lenThe IV length for ciphers with variable-size IV. This parameter is discarded by ciphers with fixed-size IV.
adThe additional data to be authenticated.
ad_lenThe length of ad.
inputThe buffer holding the input data.
ilenThe length of the input data.
outputThe buffer for the output data. Must be able to hold at least ilen.
olenThe length of the output data, to be updated with the actual number of Bytes written.
tagThe buffer holding the authentication tag.
tag_lenThe length of the authentication tag.
Returns
0 on success, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or MBEDTLS_ERR_CIPHER_AUTH_FAILED if data is not authentic, or a cipher-specific error code on failure for any other reason.
Note
If the data is not authentic, then the output buffer is zeroed out to prevent the unauthentic plaintext being used, making this interface safer.
int mbedtls_cipher_auth_encrypt ( mbedtls_cipher_context_t ctx,
const unsigned char *  iv,
size_t  iv_len,
const unsigned char *  ad,
size_t  ad_len,
const unsigned char *  input,
size_t  ilen,
unsigned char *  output,
size_t *  olen,
unsigned char *  tag,
size_t  tag_len 
)

The generic autenticated encryption (AEAD) function.

Parameters
ctxThe generic cipher context.
ivThe IV to use, or NONCE_COUNTER for CTR-mode ciphers.
iv_lenThe IV length for ciphers with variable-size IV. This parameter is discarded by ciphers with fixed-size IV.
adThe additional data to authenticate.
ad_lenThe length of ad.
inputThe buffer holding the input data.
ilenThe length of the input data.
outputThe buffer for the output data. Must be able to hold at least ilen.
olenThe length of the output data, to be updated with the actual number of Bytes written.
tagThe buffer for the authentication tag.
tag_lenThe desired length of the authentication tag.
Returns
0 on success, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or a cipher-specific error code.
int mbedtls_cipher_check_tag ( mbedtls_cipher_context_t ctx,
const unsigned char *  tag,
size_t  tag_len 
)

This function checks the tag for AEAD ciphers.

Only supported with GCM. Must be called after mbedtls_cipher_finish().

Parameters
ctxThe generic cipher context.
tagThe buffer holding the tag.
tag_lenThe length of the tag to check.
Returns
0 on success, or a specific error code on failure.
int mbedtls_cipher_crypt ( mbedtls_cipher_context_t ctx,
const unsigned char *  iv,
size_t  iv_len,
const unsigned char *  input,
size_t  ilen,
unsigned char *  output,
size_t *  olen 
)

The generic all-in-one encryption/decryption function, for all ciphers except AEAD constructs.

Parameters
ctxThe generic cipher context.
ivThe IV to use, or NONCE_COUNTER for CTR-mode ciphers.
iv_lenThe IV length for ciphers with variable-size IV. This parameter is discarded by ciphers with fixed-size IV.
inputThe buffer holding the input data.
ilenThe length of the input data.
outputThe buffer for the output data. Must be able to hold at least ilen + block_size. Must not be the same buffer as input.
olenThe length of the output data, to be updated with the actual number of Bytes written.
Note
Some ciphers do not use IVs nor nonce. For these ciphers, use iv = NULL and iv_len = 0.
Returns
0 on success, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA, or MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption expected a full block but was not provided one, or MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding while decrypting, or a cipher-specific error code on failure for any other reason.
int mbedtls_cipher_finish ( mbedtls_cipher_context_t ctx,
unsigned char *  output,
size_t *  olen 
)

The generic cipher finalization function.

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

Parameters
ctxThe generic cipher context.
outputThe buffer to write data to. Needs block_size available.
olenThe length of the data written to the output buffer.
Returns
0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails, MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED if decryption expected a full block but was not provided one, MBEDTLS_ERR_CIPHER_INVALID_PADDING on invalid padding while decrypting, or a cipher-specific error code on failure for any other reason.
void mbedtls_cipher_free ( mbedtls_cipher_context_t ctx)

This function frees and clears the cipher-specific context of ctx.

Freeing ctx itself remains the responsibility of the caller.

const mbedtls_cipher_info_t* mbedtls_cipher_info_from_string ( const char *  cipher_name)

This function retrieves 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 mbedtls_cipher_info_t* mbedtls_cipher_info_from_type ( const mbedtls_cipher_type_t  cipher_type)

This function retrieves 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 mbedtls_cipher_info_t* mbedtls_cipher_info_from_values ( const mbedtls_cipher_id_t  cipher_id,
int  key_bitlen,
const mbedtls_cipher_mode_t  mode 
)

This function retrieves the cipher-information structure associated with the given cipher ID, key size and mode.

Parameters
cipher_idThe ID of the cipher to search for. For example, #MBEDTLS_CIPHER_ID_AES.
key_bitlenThe length of the key in bits.
modeThe cipher mode. For example, #MBEDTLS_MODE_CBC.
Returns
The cipher information structure associated with the given cipher_id, or NULL if not found.
const int* mbedtls_cipher_list ( void  )

This function retrieves the list of ciphers supported by the generic cipher module.

Returns
A statically-allocated array of ciphers. The last entry is zero.
int mbedtls_cipher_reset ( mbedtls_cipher_context_t ctx)

This function resets the cipher state.

Parameters
ctxThe generic cipher context.
Returns
0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails.
int mbedtls_cipher_set_iv ( mbedtls_cipher_context_t ctx,
const unsigned char *  iv,
size_t  iv_len 
)

This function sets the initialization vector (IV) or nonce.

Parameters
ctxThe generic cipher context.
ivThe IV to use, or NONCE_COUNTER for CTR-mode ciphers.
iv_lenThe IV length for ciphers with variable-size IV. This parameter is discarded by ciphers with fixed-size IV.
Returns
0 on success, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA
Note
Some ciphers do not use IVs nor nonce. For these ciphers, this function has no effect.
int mbedtls_cipher_set_padding_mode ( mbedtls_cipher_context_t ctx,
mbedtls_cipher_padding_t  mode 
)

This function sets the padding mode, for cipher modes that use padding.

The default passing mode is PKCS7 padding.

Parameters
ctxThe generic cipher context.
modeThe padding mode.
Returns
0 on success, MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE if the selected padding mode is not supported, or MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode does not support padding.
int mbedtls_cipher_setkey ( mbedtls_cipher_context_t ctx,
const unsigned char *  key,
int  key_bitlen,
const mbedtls_operation_t  operation 
)

This function sets the key to use with the given context.

Parameters
ctxThe generic cipher context. May not be NULL. Must have been initialized using mbedtls_cipher_info_from_type() or mbedtls_cipher_info_from_string().
keyThe key to use.
key_bitlenThe key length to use, in bits.
operationThe operation that the key will be used for: #MBEDTLS_ENCRYPT or #MBEDTLS_DECRYPT.
Returns
0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails, or a cipher-specific error code.
int mbedtls_cipher_setup ( mbedtls_cipher_context_t ctx,
const mbedtls_cipher_info_t cipher_info 
)

This function initializes and fills the cipher-context structure with the appropriate values.

It also clears the structure.

Parameters
ctxThe context to initialize. May not be NULL.
cipher_infoThe cipher to use.
Returns
0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA on parameter failure, MBEDTLS_ERR_CIPHER_ALLOC_FAILED if allocation of the cipher-specific context failed.
int mbedtls_cipher_update ( mbedtls_cipher_context_t ctx,
const unsigned char *  input,
size_t  ilen,
unsigned char *  output,
size_t *  olen 
)

The generic cipher update function.

It encrypts or decrypts using the given cipher context. Writes as many block-sized blocks of data as possible to output. Any data that cannot be written immediately is either added to the next block, or flushed when mbedtls_cipher_finish() is called. Exception: For MBEDTLS_MODE_ECB, expects a single block in size. For example, 16 Bytes for AES.

Parameters
ctxThe generic cipher context.
inputThe buffer holding the input data.
ilenThe length of the input data.
outputThe buffer for the output data. Must be able to hold at least ilen + block_size. Must not be the same buffer as input.
olenThe length of the output data, to be updated with the actual number of Bytes written.
Returns
0 on success, MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA if parameter verification fails, MBEDTLS_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 mbedtls_cipher_finish(). Must have ilen as a multiple of the block_size.
int mbedtls_cipher_update_ad ( mbedtls_cipher_context_t ctx,
const unsigned char *  ad,
size_t  ad_len 
)

This function adds additional data for AEAD ciphers.

Only supported with GCM. Must be called exactly once, after mbedtls_cipher_reset().

Parameters
ctxThe generic cipher context.
adThe additional data to use.
ad_lenthe Length of ad.
Returns
0 on success, or a specific error code on failure.
int mbedtls_cipher_write_tag ( mbedtls_cipher_context_t ctx,
unsigned char *  tag,
size_t  tag_len 
)

This function writes a tag for AEAD ciphers.

Only supported with GCM. Must be called after mbedtls_cipher_finish().

Parameters
ctxThe generic cipher context.
tagThe buffer to write the tag to.
tag_lenThe length of the tag to write.
Returns
0 on success, or a specific error code on failure.