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 hmac_done.c
  HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer
*/

#ifdef LTC_HMAC

#define LTC_HMAC_BLOCKSIZE hash_descriptor[hash].blocksize

/**
   Terminate an HMAC session
   @param hmac    The HMAC state
   @param out     [out] The destination of the HMAC authentication tag
   @param outlen  [in/out]  The max size and resulting size of the HMAC authentication tag
   @return CRYPT_OK if successful
*/
int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen)
{
    unsigned char buf[MAXBLOCKSIZE], isha[MAXBLOCKSIZE];
    unsigned long hashsize, i;
    int hash, err;

    LTC_ARGCHK(hmac  != NULL);
    LTC_ARGCHK(out   != NULL);

    /* test hash */
    hash = hmac->hash;
    if((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }

    /* get the hash message digest size */
    hashsize = hash_descriptor[hash].hashsize;

    if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
       goto LBL_ERR;
    }

    /* Create the second HMAC vector vector for step (3) */
    for(i=0; i < LTC_HMAC_BLOCKSIZE; i++) {
        buf[i] = hmac->key[i] ^ 0x5C;
    }

    /* Now calculate the "outer" hash for step (5), (6), and (7) */
    if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) {
       goto LBL_ERR;
    }
    if ((err = hash_descriptor[hash].process(&hmac->md, buf, LTC_HMAC_BLOCKSIZE)) != CRYPT_OK) {
       goto LBL_ERR;
    }
    if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) {
       goto LBL_ERR;
    }
    if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) {
       goto LBL_ERR;
    }

    /* copy to output  */
    for (i = 0; i < hashsize && i < *outlen; i++) {
        out[i] = buf[i];
    }
    *outlen = i;

    err = CRYPT_OK;
LBL_ERR:
    XFREE(hmac->key);
#ifdef LTC_CLEAN_STACK
    zeromem(isha, hashsize);
    zeromem(buf,  hashsize);
    zeromem(hmac, sizeof(*hmac));
#endif

    return err;
}

#endif

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