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_setiv.c
   LRW_MODE implementation, Set the current IV, Tom St Denis
*/

#ifdef LTC_LRW_MODE

/**
  Set the IV for LRW
  @param IV      The IV, must be 16 octets
  @param len     Length ... must be 16 :-)
  @param lrw     The LRW state to update
  @return CRYPT_OK if successful
*/
int lrw_setiv(const unsigned char *IV, unsigned long len, symmetric_LRW *lrw)
{
   int           err;
#ifdef LTC_LRW_TABLES
   unsigned char T[16];
   int           x, y;
#endif
   LTC_ARGCHK(IV != NULL);
   LTC_ARGCHK(lrw != NULL);

   if (len != 16) {
      return CRYPT_INVALID_ARG;
   }

   if ((err = cipher_is_valid(lrw->cipher)) != CRYPT_OK) {
      return err;
   }

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

   /* check if we have to actually do work */
   if (cipher_descriptor[lrw->cipher].accel_lrw_encrypt != NULL && cipher_descriptor[lrw->cipher].accel_lrw_decrypt != NULL) {
       /* we have accelerators, let's bail since they don't use lrw->pad anyways */
       return CRYPT_OK;
   }

#ifdef LTC_LRW_TABLES
   XMEMCPY(T, &lrw->PC[0][IV[0]][0], 16);
   for (x = 1; x < 16; x++) {
#ifdef LTC_FAST
       for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
           *(LTC_FAST_TYPE_PTR_CAST(T + y)) ^= *(LTC_FAST_TYPE_PTR_CAST(&lrw->PC[x][IV[x]][y]));
       }
#else
       for (y = 0; y < 16; y++) {
           T[y] ^= lrw->PC[x][IV[x]][y];
       }
#endif
   }
   XMEMCPY(lrw->pad, T, 16);
#else
   gcm_gf_mult(lrw->tweak, IV, lrw->pad);
#endif

   return CRYPT_OK;
}


#endif
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