view libtomcrypt/src/mac/pelican/pelican.c @ 1663:c795520269f9

Fallback for key gen without hard link support (#89) Add a non-atomic fallback for key generation on platforms where link() is not permitted (such as most stock Android installs) or on filesystems without hard link support (such as FAT).
author Matt Robinson <git@nerdoftheherd.com>
date Sat, 14 Mar 2020 14:37:35 +0000
parents 6dba84798cd5
children
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */
#include "tomcrypt.h"

/**
   @file pelican.c
   Pelican MAC, initialize state, by Tom St Denis
*/

#ifdef LTC_PELICAN

#define __LTC_AES_TAB_C__
#define ENCRYPT_ONLY
#define PELI_TAB
#include "../../ciphers/aes/aes_tab.c"

/**
   Initialize a Pelican state
   @param pelmac    The Pelican state to initialize
   @param key       The secret key
   @param keylen    The length of the secret key (octets)
   @return CRYPT_OK if successful
*/
int pelican_init(pelican_state *pelmac, const unsigned char *key, unsigned long keylen)
{
    int err;

    LTC_ARGCHK(pelmac != NULL);
    LTC_ARGCHK(key    != NULL);

#ifdef LTC_FAST
    if (16 % sizeof(LTC_FAST_TYPE)) {
        return CRYPT_INVALID_ARG;
    }
#endif

    if ((err = aes_setup(key, keylen, 0, &pelmac->K)) != CRYPT_OK) {
       return err;
    }

    zeromem(pelmac->state, 16);
    aes_ecb_encrypt(pelmac->state, pelmac->state, &pelmac->K);
    pelmac->buflen = 0;

    return CRYPT_OK;
}

static void _four_rounds(pelican_state *pelmac)
{
    ulong32 s0, s1, s2, s3, t0, t1, t2, t3;
    int r;

    LOAD32H(s0, pelmac->state      );
    LOAD32H(s1, pelmac->state  +  4);
    LOAD32H(s2, pelmac->state  +  8);
    LOAD32H(s3, pelmac->state  + 12);
    for (r = 0; r < 4; r++) {
        t0 =
            Te0(byte(s0, 3)) ^
            Te1(byte(s1, 2)) ^
            Te2(byte(s2, 1)) ^
            Te3(byte(s3, 0));
        t1 =
            Te0(byte(s1, 3)) ^
            Te1(byte(s2, 2)) ^
            Te2(byte(s3, 1)) ^
            Te3(byte(s0, 0));
        t2 =
            Te0(byte(s2, 3)) ^
            Te1(byte(s3, 2)) ^
            Te2(byte(s0, 1)) ^
            Te3(byte(s1, 0));
        t3 =
            Te0(byte(s3, 3)) ^
            Te1(byte(s0, 2)) ^
            Te2(byte(s1, 1)) ^
            Te3(byte(s2, 0));
        s0 = t0; s1 = t1; s2 = t2; s3 = t3;
    }
    STORE32H(s0, pelmac->state      );
    STORE32H(s1, pelmac->state  +  4);
    STORE32H(s2, pelmac->state  +  8);
    STORE32H(s3, pelmac->state  + 12);
}

/**
  Process a block of text through Pelican
  @param pelmac       The Pelican MAC state
  @param in           The input
  @param inlen        The length input (octets)
  @return CRYPT_OK on success
  */
int pelican_process(pelican_state *pelmac, const unsigned char *in, unsigned long inlen)
{

   LTC_ARGCHK(pelmac != NULL);
   LTC_ARGCHK(in     != NULL);

   /* check range */
   if (pelmac->buflen < 0 || pelmac->buflen > 15) {
      return CRYPT_INVALID_ARG;
   }

#ifdef LTC_FAST
   if (pelmac->buflen == 0) {
      while (inlen & ~15) {
         int x;
         for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pelmac->state + x)) ^= *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)in + x));
         }
         _four_rounds(pelmac);
         in    += 16;
         inlen -= 16;
      }
   }
#endif

   while (inlen--) {
       pelmac->state[pelmac->buflen++] ^= *in++;
       if (pelmac->buflen == 16) {
          _four_rounds(pelmac);
          pelmac->buflen = 0;
       }
   }
   return CRYPT_OK;
}

/**
  Terminate Pelican MAC
  @param pelmac      The Pelican MAC state
  @param out         [out] The TAG
  @return CRYPT_OK on sucess
*/
int pelican_done(pelican_state *pelmac, unsigned char *out)
{
   LTC_ARGCHK(pelmac  != NULL);
   LTC_ARGCHK(out     != NULL);

   /* check range */
   if (pelmac->buflen < 0 || pelmac->buflen > 16) {
      return CRYPT_INVALID_ARG;
   }

   if  (pelmac->buflen == 16) {
       _four_rounds(pelmac);
       pelmac->buflen = 0;
   }
   pelmac->state[pelmac->buflen++] ^= 0x80;
   aes_ecb_encrypt(pelmac->state, out, &pelmac->K);
   aes_done(&pelmac->K);
   return CRYPT_OK;
}

#endif

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