ccm.c File Reference

#include <string.h>
#include "tinydtls.h"
#include "global.h"
#include "numeric.h"
#include "ccm.h"
#include <assert.h>

Go to the source code of this file.

Macros
#define	CCM_FLAGS(A, M, L)   (((A > 0) << 6) | (((M - 2)/2) << 3) | (L - 1))
#define	MASK_L(_L)   ((1 << 8 * _L) - 1)
#define	SET_COUNTER(A, L, cnt, C)

Functions
static void	block0 (size_t M, size_t L, size_t la, size_t lm, unsigned char nonce[DTLS_CCM_BLOCKSIZE], unsigned char *result)
static void	add_auth_data (rijndael_ctx *ctx, const unsigned char *msg, size_t la, unsigned char B[DTLS_CCM_BLOCKSIZE], unsigned char X[DTLS_CCM_BLOCKSIZE])
static void	encrypt (rijndael_ctx *ctx, size_t L, unsigned long counter, unsigned char *msg, size_t len, unsigned char A[DTLS_CCM_BLOCKSIZE], unsigned char S[DTLS_CCM_BLOCKSIZE])
static void	mac (rijndael_ctx *ctx, unsigned char *msg, size_t len, unsigned char B[DTLS_CCM_BLOCKSIZE], unsigned char X[DTLS_CCM_BLOCKSIZE])
long int	dtls_ccm_encrypt_message (rijndael_ctx *ctx, size_t M, size_t L, unsigned char nonce[DTLS_CCM_BLOCKSIZE], unsigned char *msg, size_t lm, const unsigned char *aad, size_t la)
long int	dtls_ccm_decrypt_message (rijndael_ctx *ctx, size_t M, size_t L, unsigned char nonce[DTLS_CCM_BLOCKSIZE], unsigned char *msg, size_t lm, const unsigned char *aad, size_t la)

Macro Definition Documentation

#define CCM_FLAGS	(		A,
			M,
			L
	)		(((A > 0) << 6) | (((M - 2)/2) << 3) | (L - 1))

Definition at line 29 of file ccm.c.

#define MASK_L

(

_L

)

((1 << 8 * _L) - 1)

Definition at line 31 of file ccm.c.

#define SET_COUNTER	(		A,
			L,
			cnt,
			C
	)

Value:

{                   \
    unsigned int i_;                                                    \
    memset((A) + DTLS_CCM_BLOCKSIZE - (L), 0, (L));         \
    (C) = (cnt) & MASK_L(L);                        \
    for (i_ = DTLS_CCM_BLOCKSIZE - 1; (C) && (i_ > (L)); --i_, (C) >>= 8) \
      (A)[i_] |= (C) & 0xFF;                        \
  }

Definition at line 33 of file ccm.c.

Function Documentation

static void add_auth_data ( rijndael_ctx *  ctx, const unsigned char *  msg, size_t  la, unsigned char  B[DTLS_CCM_BLOCKSIZE], unsigned char  X[DTLS_CCM_BLOCKSIZE]  )

static

Creates the CBC-MAC for the additional authentication data that is sent in cleartext.

Parameters

ctx	The crypto context for the AES encryption.
msg	The message starting with the additional authentication data.
la	The number of additional authentication bytes in msg.
B	The input buffer for crypto operations. When this function is called, B must be initialized with B0 (the first authentication block.
X	The output buffer where the result of the CBC calculation is placed.

Returns

The result is written to X.

Definition at line 76 of file ccm.c.

static void block0 ( size_t  M, size_t  L, size_t  la, size_t  lm, unsigned char  nonce[DTLS_CCM_BLOCKSIZE], unsigned char *  result  )

inlinestatic

Definition at line 42 of file ccm.c.

long int dtls_ccm_decrypt_message	(	rijndael_ctx *	ctx,
		size_t	M,
		size_t	L,
		unsigned char	nonce[DTLS_CCM_BLOCKSIZE],
		unsigned char *	msg,
		size_t	lm,
		const unsigned char *	aad,
		size_t	la
	)

Definition at line 232 of file ccm.c.

long int dtls_ccm_encrypt_message	(	rijndael_ctx *	ctx,
		size_t	M,
		size_t	L,
		unsigned char	nonce[DTLS_CCM_BLOCKSIZE],
		unsigned char *	msg,
		size_t	lm,
		const unsigned char *	aad,
		size_t	la
	)

Authenticates and encrypts a message using AES in CCM mode. Please see also RFC 3610 for the meaning of M, L, lm and la.

Parameters

ctx	The initialized rijndael_ctx object to be used for AES operations.
M	The number of authentication octets.
L	The number of bytes used to encode the message length.
N	The nonce value to use. You must provide DTLS_CCM_BLOCKSIZE nonce octets, although only the first 16 - L - 1 are used.
msg	The message to encrypt. The first la octets are additional authentication data that will be cleartext. Note that the encryption operation modifies the contents of msg and adds M bytes MAC. Therefore, the buffer must be at least lm + M bytes large.
lm	The actual length of msg.
aad	A pointer to the additional authentication data (can be NULL if la is zero).
la	The number of additional authentication octets (may be zero).

Returns

FIXME

Definition at line 168 of file ccm.c.

static void encrypt ( rijndael_ctx *  ctx, size_t  L, unsigned long  counter, unsigned char *  msg, size_t  len, unsigned char  A[DTLS_CCM_BLOCKSIZE], unsigned char  S[DTLS_CCM_BLOCKSIZE]  )

inlinestatic

Definition at line 141 of file ccm.c.

static void mac ( rijndael_ctx *  ctx, unsigned char *  msg, size_t  len, unsigned char  B[DTLS_CCM_BLOCKSIZE], unsigned char  X[DTLS_CCM_BLOCKSIZE]  )

inlinestatic

Definition at line 154 of file ccm.c.