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_decode_object_identifier.c
  ASN.1 DER, Decode Object Identifier, Tom St Denis
*/

#ifdef LTC_DER
/**
  Decode OID data and store the array of integers in words
  @param in      The OID DER encoded data
  @param inlen   The length of the OID data
  @param words   [out] The destination of the OID words
  @param outlen  [in/out] The number of OID words
  @return CRYPT_OK if successful
*/
int der_decode_object_identifier(const unsigned char *in,    unsigned long  inlen,
                                       unsigned long *words, unsigned long *outlen)
{
   unsigned long x, y, t, len;
   int err;

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

   /* header is at least 3 bytes */
   if (inlen < 3) {
      return CRYPT_INVALID_PACKET;
   }

   /* must be room for at least two words */
   if (*outlen < 2) {
      *outlen = 2;
      return CRYPT_BUFFER_OVERFLOW;
   }

   /* decode the packet header */
   x = 0;
   if ((in[x++] & 0x1F) != 0x06) {
      return CRYPT_INVALID_PACKET;
   }

   /* get the length */
   if (in[x] < 128) {
      len = in[x++];
   } else {
      if (in[x] < 0x81 || in[x] > 0x82) {
         return CRYPT_INVALID_PACKET;
      }
      y   = in[x++] & 0x7F;
      len = 0;
      while (y--) {
         len = (len << 8) | (unsigned long)in[x++];
      }
   }

   if (len < 1 || (len + x) > inlen) {
      return CRYPT_INVALID_PACKET;
   }

   /* decode words */
   y = 0;
   t = 0;
   while (len--) {
      t = (t << 7) | (in[x] & 0x7F);
      if (!(in[x++] & 0x80)) {
         /* store t */
         if (y >= *outlen) {
            y++;
         } else {
            if (y == 0) {
               words[0] = t / 40;
               words[1] = t % 40;
               y = 2;
            } else {
               words[y++] = t;
            }
         }
         t = 0;
      }
   }

   if (y > *outlen) {
      err =  CRYPT_BUFFER_OVERFLOW;
   } else {
      err =  CRYPT_OK;
   }

   *outlen = y;
   return err;
}

#endif

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