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 der_encode_object_identifier.c
  ASN.1 DER, Encode Object Identifier, Tom St Denis
*/

#ifdef LTC_DER
/**
  Encode an OID
  @param words   The words to encode  (upto 32-bits each)
  @param nwords  The number of words in the OID
  @param out     [out] Destination of OID data
  @param outlen  [in/out] The max and resulting size of the OID
  @return CRYPT_OK if successful
*/
int der_encode_object_identifier(unsigned long *words, unsigned long  nwords,
                                 unsigned char *out,   unsigned long *outlen)
{
   unsigned long i, x, y, z, t, mask, wordbuf;
   int           err;

   LTC_ARGCHK(words  != NULL);
   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);

   /* check length */
   if ((err = der_length_object_identifier(words, nwords, &x)) != CRYPT_OK) {
      return err;
   }
   if (x > *outlen) {
      *outlen = x;
      return CRYPT_BUFFER_OVERFLOW;
   }

   /* compute length to store OID data */
   z = 0;
   wordbuf = words[0] * 40 + words[1];
   for (y = 1; y < nwords; y++) {
       t = der_object_identifier_bits(wordbuf);
       z += t/7 + ((t%7) ? 1 : 0) + (wordbuf == 0 ? 1 : 0);
       if (y < nwords - 1) {
          wordbuf = words[y + 1];
       }
   }

   /* store header + length */
   x = 0;
   out[x++] = 0x06;
   if (z < 128) {
      out[x++] = (unsigned char)z;
   } else if (z < 256) {
      out[x++] = 0x81;
      out[x++] = (unsigned char)z;
   } else if (z < 65536UL) {
      out[x++] = 0x82;
      out[x++] = (unsigned char)((z>>8)&255);
      out[x++] = (unsigned char)(z&255);
   } else {
      return CRYPT_INVALID_ARG;
   }

   /* store first byte */
   wordbuf = words[0] * 40 + words[1];
   for (i = 1; i < nwords; i++) {
      /* store 7 bit words in little endian */
      t    = wordbuf & 0xFFFFFFFF;
      if (t) {
         y    = x;
         mask = 0;
         while (t) {
            out[x++] = (unsigned char)((t & 0x7F) | mask);
            t    >>= 7;
            mask  |= 0x80;  /* upper bit is set on all but the last byte */
         }
         /* now swap bytes y...x-1 */
         z = x - 1;
         while (y < z) {
            t = out[y]; out[y] = out[z]; out[z] = (unsigned char)t;
            ++y;
            --z;
         }
      } else {
         /* zero word */
         out[x++] = 0x00;
      }

      if (i < nwords - 1) {
         wordbuf = words[i + 1];
      }
   }

   *outlen = x;
   return CRYPT_OK;
}

#endif

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