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_utctime.c
  ASN.1 DER, decode a  UTCTIME, Tom St Denis
*/

#ifdef LTC_DER

static int _char_to_int(unsigned char x)
{
   switch (x)  {
      case '0': return 0;
      case '1': return 1;
      case '2': return 2;
      case '3': return 3;
      case '4': return 4;
      case '5': return 5;
      case '6': return 6;
      case '7': return 7;
      case '8': return 8;
      case '9': return 9;
      default:  return 100;
   }
}

#define DECODE_V(y, max) \
   y  = _char_to_int(buf[x])*10 + _char_to_int(buf[x+1]); \
   if (y >= max) return CRYPT_INVALID_PACKET;           \
   x += 2;

/**
  Decodes a UTC time structure in DER format (reads all 6 valid encoding formats)
  @param in     Input buffer
  @param inlen  Length of input buffer in octets
  @param out    [out] Destination of UTC time structure
  @return CRYPT_OK   if successful
*/
int der_decode_utctime(const unsigned char *in, unsigned long *inlen,
                             ltc_utctime   *out)
{
   unsigned char buf[32] = { 0 }; /* initialize as all zeroes */
   unsigned long x;
   int           y;

   LTC_ARGCHK(in    != NULL);
   LTC_ARGCHK(inlen != NULL);
   LTC_ARGCHK(out   != NULL);

   /* check header */
   if (*inlen < 2UL || (in[1] >= sizeof(buf)) || ((in[1] + 2UL) > *inlen)) {
      return CRYPT_INVALID_PACKET;
   }

   /* decode the string */
   for (x = 0; x < in[1]; x++) {
       y = der_ia5_value_decode(in[x+2]);
       if (y == -1) {
          return CRYPT_INVALID_PACKET;
       }
       buf[x] = y;
   }
   *inlen = 2 + x;


   /* possible encodings are
YYMMDDhhmmZ
YYMMDDhhmm+hh'mm'
YYMMDDhhmm-hh'mm'
YYMMDDhhmmssZ
YYMMDDhhmmss+hh'mm'
YYMMDDhhmmss-hh'mm'

    So let's do a trivial decode upto [including] mm
   */

    x = 0;
    DECODE_V(out->YY, 100);
    DECODE_V(out->MM, 13);
    DECODE_V(out->DD, 32);
    DECODE_V(out->hh, 24);
    DECODE_V(out->mm, 60);

    /* clear timezone and seconds info */
    out->off_dir = out->off_hh = out->off_mm = out->ss = 0;

    /* now is it Z, +, - or 0-9 */
    if (buf[x] == 'Z') {
       return CRYPT_OK;
    } else if (buf[x] == '+' || buf[x] == '-') {
       out->off_dir = (buf[x++] == '+') ? 0 : 1;
       DECODE_V(out->off_hh, 24);
       DECODE_V(out->off_mm, 60);
       return CRYPT_OK;
    }

    /* decode seconds */
    DECODE_V(out->ss, 60);

    /* now is it Z, +, - */
    if (buf[x] == 'Z') {
       return CRYPT_OK;
    } else if (buf[x] == '+' || buf[x] == '-') {
       out->off_dir = (buf[x++] == '+') ? 0 : 1;
       DECODE_V(out->off_hh, 24);
       DECODE_V(out->off_mm, 60);
       return CRYPT_OK;
    } else {
       return CRYPT_INVALID_PACKET;
    }
}

#endif

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