aes_cmac.c File Reference

#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "aes_cmac.h"
#include "../common/insecure_memzero.h"

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Functions
void	aes_cmac_encrypt (const aes_cmac_context_t *ctx, const uint8_t *message, const uint16_t message_len, uint8_t *mac)
uint8_t	aes_cmac_init (uint8_t *key, uint16_t key_len, aes_cmac_context_t *ctx)
void	aes_cmac_destroy (aes_cmac_context_t *ctx)

Function Documentation

aes_cmac_destroy()

void aes_cmac_destroy

(

aes_cmac_context_t *

ctx

)

Definition at line 147 of file aes_cmac.c.

                                               {
  if (!ctx)
    return;
  aes_destroy(&(ctx->aes_ctx));
  insecure_memzero(ctx, sizeof(aes_cmac_context_t));
}

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aes_cmac_encrypt()

void aes_cmac_encrypt	(	const aes_cmac_context_t *	ctx,
		const uint8_t *	message,
		const uint16_t	message_len,
		uint8_t *	mac )

Definition at line 85 of file aes_cmac.c.

                                                                {
 
  uint8_t n_blocks;
  uint8_t i;
  uint8_t remaining_bytes;
 
  uint8_t M[AES_BLOCK_SIZE];
  uint8_t *ptr = (uint8_t *) message;
 
  memcpy(mac, zero, AES_BLOCK_SIZE);
  insecure_memzero(M, AES_BLOCK_SIZE);
 
  if (message_len == 0)
    n_blocks = 0;
  else
    n_blocks = (message_len + (AES_BLOCK_SIZE - 1)) / AES_BLOCK_SIZE - 1;
 
  remaining_bytes = (message_len % AES_BLOCK_SIZE);
 
  for (i = 0; i < n_blocks; i++) {
    do_xor(ptr, mac);
    aes_encrypt(mac, mac, &ctx->aes_ctx);
    ptr += AES_BLOCK_SIZE;
  }
 
  if (remaining_bytes == 0) {
    if (message != NULL && message_len != 0) {
      memcpy(M, ptr, AES_BLOCK_SIZE);
      do_xor(ctx->k1, M);
    } else {
      do_pad(M, 0);
      do_xor(ctx->k2, M);
    }
  } else {
    memcpy(M, ptr, remaining_bytes);
    do_pad(M, remaining_bytes);
    do_xor(ctx->k2, M);
  }
 
  do_xor(M, mac);
 
  aes_encrypt(mac, mac, &ctx->aes_ctx);
}

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aes_cmac_init()

uint8_t aes_cmac_init	(	uint8_t *	key,
		uint16_t	key_len,
		aes_cmac_context_t *	ctx )

Definition at line 130 of file aes_cmac.c.

                                                                               {
 
  uint8_t L[AES_BLOCK_SIZE];
 
  insecure_memzero(zero, AES_BLOCK_SIZE);
 
  aes_set_encrypt_key(key, key_len, &ctx->aes_ctx);
  aes_encrypt(zero, L, &ctx->aes_ctx);
 
  cmac_generate_subkey(L, ctx->k1);
  cmac_generate_subkey(ctx->k1, ctx->k2);
 
  aes_cmac_encrypt(ctx, zero, AES_BLOCK_SIZE, ctx->mac);
 
  return 0;
}

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