Add Chacha20-Poly1305, AES128-GCM and AES256-GCM support (#93) * Add Chacha20-Poly1305 authenticated encryption * Add general AEAD approach. * Add [email protected] algo using LibTomCrypt chacha and poly1305 routines. Chacha20-Poly1305 is generally faster than AES256 on CPU w/o dedicated AES instructions, having the same key size. Compiling in will add ~5,5kB to binary size on x86-64. function old new delta chacha_crypt - 1397 +1397 _poly1305_block - 608 +608 poly1305_done - 595 +595 dropbear_chachapoly_crypt - 457 +457 .rodata 26976 27392 +416 poly1305_process - 290 +290 poly1305_init - 221 +221 chacha_setup - 218 +218 encrypt_packet 1068 1270 +202 dropbear_chachapoly_getlength - 147 +147 decrypt_packet 756 897 +141 chacha_ivctr64 - 137 +137 read_packet 543 637 +94 dropbear_chachapoly_start - 94 +94 read_kex_algos 792 880 +88 chacha_keystream - 69 +69 dropbear_mode_chachapoly - 48 +48 sshciphers 280 320 +40 dropbear_mode_none 24 48 +24 dropbear_mode_ctr 24 48 +24 dropbear_mode_cbc 24 48 +24 dropbear_chachapoly_mac - 24 +24 dropbear_chachapoly - 24 +24 gen_new_keys 848 854 +6 ------------------------------------------------------------------------------ (add/remove: 14/0 grow/shrink: 10/0 up/down: 5388/0) Total: 5388 bytes * Add AES128-GCM and AES256-GCM authenticated encryption * Add general AES-GCM mode. * Add [email protected] and [email protected] algo using LibTomCrypt gcm routines. AES-GCM is combination of AES CTR mode and GHASH, slower than AES-CTR on CPU w/o dedicated AES/GHASH instructions therefore disabled by default. Compiling in will add ~6kB to binary size on x86-64. function old new delta gcm_process - 1060 +1060 .rodata 26976 27808 +832 gcm_gf_mult - 820 +820 gcm_add_aad - 660 +660 gcm_shift_table - 512 +512 gcm_done - 471 +471 gcm_add_iv - 384 +384 gcm_init - 347 +347 dropbear_gcm_crypt - 309 +309 encrypt_packet 1068 1270 +202 decrypt_packet 756 897 +141 gcm_reset - 118 +118 read_packet 543 637 +94 read_kex_algos 792 880 +88 sshciphers 280 360 +80 gcm_mult_h - 80 +80 dropbear_gcm_start - 62 +62 dropbear_mode_gcm - 48 +48 dropbear_mode_none 24 48 +24 dropbear_mode_ctr 24 48 +24 dropbear_mode_cbc 24 48 +24 dropbear_ghash - 24 +24 dropbear_gcm_getlength - 24 +24 gen_new_keys 848 854 +6 ------------------------------------------------------------------------------ (add/remove: 14/0 grow/shrink: 10/0 up/down: 6434/0) Total: 6434 bytes

/* 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"

#ifdef LTC_MDSA
/**
  Generate a random number N with given bitlength (note: MSB can be 0)
*/

int rand_bn_bits(void *N, int bits, prng_state *prng, int wprng)
{
   int res, bytes;
   unsigned char *buf, mask;

   LTC_ARGCHK(N != NULL);
   LTC_ARGCHK(bits > 1);

   /* check PRNG */
   if ((res = prng_is_valid(wprng)) != CRYPT_OK) return res;

   bytes = (bits+7) >> 3;
   mask = 0xff << (8 - bits % 8);

   /* allocate buffer */
   if ((buf = XCALLOC(1, bytes)) == NULL) return CRYPT_MEM;

   /* generate random bytes */
   if (prng_descriptor[wprng].read(buf, bytes, prng) != (unsigned long)bytes) {
      res = CRYPT_ERROR_READPRNG;
      goto cleanup;
   }
   /* mask bits */
   buf[0] &= ~mask;
   /* load value */
   if ((res = mp_read_unsigned_bin(N, buf, bytes)) != CRYPT_OK) goto cleanup;

   res = CRYPT_OK;

cleanup:
#ifdef LTC_CLEAN_STACK
   zeromem(buf, bytes);
#endif
   XFREE(buf);
   return res;
}

/**
  Generate a random number N in a range: 1 <= N < limit
*/
int rand_bn_upto(void *N, void *limit, prng_state *prng, int wprng)
{
   int res, bits;

   LTC_ARGCHK(N != NULL);
   LTC_ARGCHK(limit != NULL);

   bits = mp_count_bits(limit);
   do {
     res = rand_bn_bits(N, bits, prng, wprng);
     if (res != CRYPT_OK) return res;
   } while (mp_cmp_d(N, 0) != LTC_MP_GT || mp_cmp(N, limit) != LTC_MP_LT);

   return CRYPT_OK;
}
#endif

/* ref:         $Format:%D$ */
/* git commit:  $Format:%H$ */
/* commit time: $Format:%ai$ */