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_utctime.c
  ASN.1 DER, encode a GeneralizedTime, Steffen Jaeckel
  Based on der_encode_utctime.c
*/

#ifdef LTC_DER

static const char * const baseten = "0123456789";

#define STORE_V(y) do {\
    out[x++] = der_ia5_char_encode(baseten[(y/10) % 10]); \
    out[x++] = der_ia5_char_encode(baseten[y % 10]); \
} while(0)

#define STORE_V4(y) do {\
    out[x++] = der_ia5_char_encode(baseten[(y/1000) % 10]); \
    out[x++] = der_ia5_char_encode(baseten[(y/100) % 10]); \
    out[x++] = der_ia5_char_encode(baseten[(y/10) % 10]); \
    out[x++] = der_ia5_char_encode(baseten[y % 10]); \
} while(0)

/**
  Encodes a Generalized time structure in DER format
  @param gtime        The GeneralizedTime structure to encode
  @param out          The destination of the DER encoding of the GeneralizedTime structure
  @param outlen       [in/out] The length of the DER encoding
  @return CRYPT_OK if successful
*/
int der_encode_generalizedtime(ltc_generalizedtime *gtime,
                               unsigned char       *out,   unsigned long *outlen)
{
    unsigned long x, tmplen;
    int           err;

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

    if ((err = der_length_generalizedtime(gtime, &tmplen)) != CRYPT_OK) {
       return err;
    }
    if (tmplen > *outlen) {
        *outlen = tmplen;
        return CRYPT_BUFFER_OVERFLOW;
    }

    /* store header */
    out[0] = 0x18;

    /* store values */
    x = 2;
    STORE_V4(gtime->YYYY);
    STORE_V(gtime->MM);
    STORE_V(gtime->DD);
    STORE_V(gtime->hh);
    STORE_V(gtime->mm);
    STORE_V(gtime->ss);

    if (gtime->fs) {
       unsigned long divisor;
       unsigned fs = gtime->fs;
       unsigned len = 0;
       out[x++] = der_ia5_char_encode('.');
       divisor = 1;
       do {
          fs /= 10;
          divisor *= 10;
          len++;
       } while(fs != 0);
       while (len-- > 1) {
          divisor /= 10;
          out[x++] = der_ia5_char_encode(baseten[(gtime->fs/divisor) % 10]);
       }
       out[x++] = der_ia5_char_encode(baseten[gtime->fs % 10]);
    }

    if (gtime->off_mm || gtime->off_hh) {
       out[x++] = der_ia5_char_encode(gtime->off_dir ? '-' : '+');
       STORE_V(gtime->off_hh);
       STORE_V(gtime->off_mm);
    } else {
       out[x++] = der_ia5_char_encode('Z');
    }

    /* store length */
    out[1] = (unsigned char)(x - 2);

    /* all good let's return */
    *outlen = x;
    return CRYPT_OK;
}

#endif

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