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"

/**
   @file lrw_start.c
   LRW_MODE implementation, start mode, Tom St Denis
*/

#ifdef LTC_LRW_MODE

/**
  Initialize the LRW context
  @param cipher        The cipher desired, must be a 128-bit block cipher
  @param IV            The index value, must be 128-bits
  @param key           The cipher key
  @param keylen        The length of the cipher key in octets
  @param tweak         The tweak value (second key), must be 128-bits
  @param num_rounds    The number of rounds for the cipher (0 == default)
  @param lrw           [out] The LRW state
  @return CRYPT_OK on success.
*/
int lrw_start(               int   cipher,
              const unsigned char *IV,
              const unsigned char *key,       int keylen,
              const unsigned char *tweak,
                             int  num_rounds,
                   symmetric_LRW *lrw)
{
   int           err;
#ifdef LTC_LRW_TABLES
   unsigned char B[16];
   int           x, y, z, t;
#endif

   LTC_ARGCHK(IV    != NULL);
   LTC_ARGCHK(key   != NULL);
   LTC_ARGCHK(tweak != NULL);
   LTC_ARGCHK(lrw   != NULL);

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

   /* is cipher valid? */
   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
      return err;
   }
   if (cipher_descriptor[cipher].block_length != 16) {
      return CRYPT_INVALID_CIPHER;
   }

   /* schedule key */
   if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &lrw->key)) != CRYPT_OK) {
      return err;
   }
   lrw->cipher = cipher;

   /* copy the IV and tweak */
   XMEMCPY(lrw->tweak, tweak, 16);

#ifdef LTC_LRW_TABLES
   /* setup tables */
   /* generate the first table as it has no shifting (from which we make the other tables) */
   zeromem(B, 16);
   for (y = 0; y < 256; y++) {
        B[0] = y;
        gcm_gf_mult(tweak, B, &lrw->PC[0][y][0]);
   }

   /* now generate the rest of the tables based the previous table */
   for (x = 1; x < 16; x++) {
      for (y = 0; y < 256; y++) {
         /* now shift it right by 8 bits */
         t = lrw->PC[x-1][y][15];
         for (z = 15; z > 0; z--) {
             lrw->PC[x][y][z] = lrw->PC[x-1][y][z-1];
         }
         lrw->PC[x][y][0]  = gcm_shift_table[t<<1];
         lrw->PC[x][y][1] ^= gcm_shift_table[(t<<1)+1];
      }
   }
#endif

   /* generate first pad */
   return lrw_setiv(IV, 16, lrw);
}


#endif
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/* git commit:  $Format:%H$ */
/* commit time: $Format:%ai$ */