ccm.h File Reference

This file provides an API for the CCM authenticated encryption mode for block ciphers. More...

#include "config.h"
#include "cipher.h"

Include dependency graph for ccm.h:

Go to the source code of this file.

Data Structures
struct	mbedtls_ccm_context
	The CCM context-type definition. More...

Macros
#define	MBEDTLS_ERR_CCM_BAD_INPUT   -0x000D
	Bad input parameters to the function. More...
#define	MBEDTLS_ERR_CCM_AUTH_FAILED   -0x000F
	Authenticated decryption failed. More...
#define	MBEDTLS_ERR_CCM_HW_ACCEL_FAILED   -0x0011
	CCM hardware accelerator failed. More...

Typedefs
typedef struct mbedtls_ccm_context	mbedtls_ccm_context
	The CCM context-type definition. More...

Functions
void	mbedtls_ccm_init (mbedtls_ccm_context *ctx)
	This function initializes the specified CCM context, to make references valid, and prepare the context for mbedtls_ccm_setkey() or mbedtls_ccm_free(). More...
int	mbedtls_ccm_setkey (mbedtls_ccm_context *ctx, mbedtls_cipher_id_t cipher, const unsigned char *key, unsigned int keybits)
	This function initializes the CCM context set in the ctx parameter and sets the encryption key. More...
void	mbedtls_ccm_free (mbedtls_ccm_context *ctx)
	This function releases and clears the specified CCM context and underlying cipher sub-context. More...
int	mbedtls_ccm_encrypt_and_tag (mbedtls_ccm_context *ctx, 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, unsigned char *tag, size_t tag_len)
	This function encrypts a buffer using CCM. More...
int	mbedtls_ccm_star_encrypt_and_tag (mbedtls_ccm_context *ctx, 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, unsigned char *tag, size_t tag_len)
	This function encrypts a buffer using CCM*. More...
int	mbedtls_ccm_auth_decrypt (mbedtls_ccm_context *ctx, 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, const unsigned char *tag, size_t tag_len)
	This function performs a CCM authenticated decryption of a buffer. More...
int	mbedtls_ccm_star_auth_decrypt (mbedtls_ccm_context *ctx, 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, const unsigned char *tag, size_t tag_len)
	This function performs a CCM* authenticated decryption of a buffer. More...
int	mbedtls_ccm_self_test (int verbose)
	The CCM checkup routine. More...

Detailed Description

This file provides an API for the CCM authenticated encryption mode for block ciphers.

CCM combines Counter mode encryption with CBC-MAC authentication for 128-bit block ciphers.

Input to CCM includes the following elements:

• Payload - data that is both authenticated and encrypted.
• Associated data (Adata) - data that is authenticated but not encrypted, For example, a header.
• Nonce - A unique value that is assigned to the payload and the associated data.

Definition of CCM: http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf RFC 3610 "Counter with CBC-MAC (CCM)"

Related: RFC 5116 "An Interface and Algorithms for Authenticated Encryption"

Definition of CCM*: IEEE 802.15.4 - IEEE Standard for Local and metropolitan area networks Integer representation is fixed most-significant-octet-first order and the representation of octets is most-significant-bit-first order. This is consistent with RFC 3610.

Definition in file ccm.h.

Macro Definition Documentation

#define MBEDTLS_ERR_CCM_AUTH_FAILED   -0x000F

Authenticated decryption failed.

Definition at line 61 of file ccm.h.

#define MBEDTLS_ERR_CCM_BAD_INPUT   -0x000D

Bad input parameters to the function.

Definition at line 60 of file ccm.h.

#define MBEDTLS_ERR_CCM_HW_ACCEL_FAILED   -0x0011

CCM hardware accelerator failed.

Definition at line 64 of file ccm.h.

Typedef Documentation

typedef struct mbedtls_ccm_context mbedtls_ccm_context

The CCM context-type definition.

The CCM context is passed to the APIs called.

Function Documentation

int mbedtls_ccm_auth_decrypt	(	mbedtls_ccm_context *	ctx,
		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,
		const unsigned char *	tag,
		size_t	tag_len
	)

This function performs a CCM authenticated decryption of a buffer.

Parameters

ctx	The CCM context to use for decryption. This must be initialized and bound to a key.
length	The length of the input data in Bytes.
iv	The initialization vector (nonce). This must be a readable buffer of at least iv_len Bytes.
iv_len	The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12, or 13. The length L of the message length field is 15 - iv_len.
add	The additional data field. This must be a readable buffer of at least that add_len Bytes..
add_len	The length of additional data in Bytes. This must be less than 2^16 - 2^8.
input	The buffer holding the input data. If length is greater than zero, input must be a readable buffer of at least that length.
output	The buffer holding the output data. If length is greater than zero, output must be a writable buffer of at least that length.
tag	The buffer holding the authentication field. This must be a readable buffer of at least tag_len Bytes.
tag_len	The length of the authentication field to generate in Bytes: 4, 6, 8, 10, 12, 14 or 16.

Returns

0 on success. This indicates that the message is authentic.

MBEDTLS_ERR_CCM_AUTH_FAILED if the tag does not match.

A cipher-specific error code on calculation failure.

int mbedtls_ccm_encrypt_and_tag	(	mbedtls_ccm_context *	ctx,
		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,
		unsigned char *	tag,
		size_t	tag_len
	)

This function encrypts a buffer using CCM.

Note

The tag is written to a separate buffer. To concatenate the tag with the output, as done in RFC-3610: Counter with CBC-MAC (CCM), use tag = output + length, and make sure that the output buffer is at least length + tag_len wide.

Parameters

ctx	The CCM context to use for encryption. This must be initialized and bound to a key.
length	The length of the input data in Bytes.
iv	The initialization vector (nonce). This must be a readable buffer of at least iv_len Bytes.
iv_len	The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12, or 13. The length L of the message length field is 15 - iv_len.
add	The additional data field. If add_len is greater than zero, add must be a readable buffer of at least that length.
add_len	The length of additional data in Bytes. This must be less than 2^16 - 2^8.
input	The buffer holding the input data. If length is greater than zero, input must be a readable buffer of at least that length.
output	The buffer holding the output data. If length is greater than zero, output must be a writable buffer of at least that length.
tag	The buffer holding the authentication field. This must be a readable buffer of at least tag_len Bytes.
tag_len	The length of the authentication field to generate in Bytes: 4, 6, 8, 10, 12, 14 or 16.

Returns

0 on success.

A CCM or cipher-specific error code on failure.

void mbedtls_ccm_free

(

mbedtls_ccm_context *

ctx

)

This function releases and clears the specified CCM context and underlying cipher sub-context.

Parameters

ctx	The CCM context to clear. If this is NULL, the function has no effect. Otherwise, this must be initialized.

void mbedtls_ccm_init

(

mbedtls_ccm_context *

ctx

)

This function initializes the specified CCM context, to make references valid, and prepare the context for mbedtls_ccm_setkey() or mbedtls_ccm_free().

Parameters

ctx	The CCM context to initialize. This must not be NULL.

int mbedtls_ccm_self_test

(

int

verbose

)

The CCM checkup routine.

Returns

0 on success.

1 on failure.

int mbedtls_ccm_setkey	(	mbedtls_ccm_context *	ctx,
		mbedtls_cipher_id_t	cipher,
		const unsigned char *	key,
		unsigned int	keybits
	)

This function initializes the CCM context set in the ctx parameter and sets the encryption key.

Parameters

ctx	The CCM context to initialize. This must be an initialized context.
cipher	The 128-bit block cipher to use.
key	The encryption key. This must not be NULL.
keybits	The key size in bits. This must be acceptable by the cipher.

Returns

0 on success.

A CCM or cipher-specific error code on failure.

int mbedtls_ccm_star_auth_decrypt	(	mbedtls_ccm_context *	ctx,
		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,
		const unsigned char *	tag,
		size_t	tag_len
	)

This function performs a CCM* authenticated decryption of a buffer.

Note

When using this function in a variable tag length context, the tag length has to be decoded from iv and passed to this function as tag_len. (tag needs to be adjusted accordingly.)

Parameters

ctx	The CCM context to use for decryption. This must be initialized and bound to a key.
length	The length of the input data in Bytes.
iv	The initialization vector (nonce). This must be a readable buffer of at least iv_len Bytes.
iv_len	The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12, or 13. The length L of the message length field is 15 - iv_len.
add	The additional data field. This must be a readable buffer of at least that add_len Bytes.
add_len	The length of additional data in Bytes. This must be less than 2^16 - 2^8.
input	The buffer holding the input data. If length is greater than zero, input must be a readable buffer of at least that length.
output	The buffer holding the output data. If length is greater than zero, output must be a writable buffer of at least that length.
tag	The buffer holding the authentication field. This must be a readable buffer of at least tag_len Bytes.
tag_len	The length of the authentication field in Bytes. 0, 4, 6, 8, 10, 12, 14 or 16.

Warning

Passing 0 as tag_len means that the message is nos longer authenticated.

Returns

0 on success.

MBEDTLS_ERR_CCM_AUTH_FAILED if the tag does not match.

A cipher-specific error code on calculation failure.

int mbedtls_ccm_star_encrypt_and_tag	(	mbedtls_ccm_context *	ctx,
		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,
		unsigned char *	tag,
		size_t	tag_len
	)

This function encrypts a buffer using CCM*.

Note

The tag is written to a separate buffer. To concatenate the tag with the output, as done in RFC-3610: Counter with CBC-MAC (CCM), use tag = output + length, and make sure that the output buffer is at least length + tag_len wide.

When using this function in a variable tag length context, the tag length has to be encoded into the iv passed to this function.

Parameters

ctx	The CCM context to use for encryption. This must be initialized and bound to a key.
length	The length of the input data in Bytes.
iv	The initialization vector (nonce). This must be a readable buffer of at least iv_len Bytes.
iv_len	The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12, or 13. The length L of the message length field is 15 - iv_len.
add	The additional data field. This must be a readable buffer of at least add_len Bytes.
add_len	The length of additional data in Bytes. This must be less than 2^16 - 2^8.
input	The buffer holding the input data. If length is greater than zero, input must be a readable buffer of at least that length.
output	The buffer holding the output data. If length is greater than zero, output must be a writable buffer of at least that length.
tag	The buffer holding the authentication field. This must be a readable buffer of at least tag_len Bytes.
tag_len	The length of the authentication field to generate in Bytes: 0, 4, 6, 8, 10, 12, 14 or 16.

Warning

Passing 0 as tag_len means that the message is no longer authenticated.

Returns

0 on success.

A CCM or cipher-specific error code on failure.