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_init.c
  HMAC support, initialize state, Tom St Denis/Dobes Vandermeer
*/

#ifdef LTC_HMAC

#define LTC_HMAC_BLOCKSIZE hash_descriptor[hash].blocksize

/**
   Initialize an HMAC context.
   @param hmac     The HMAC state
   @param hash     The index of the hash you want to use 
   @param key      The secret key
   @param keylen   The length of the secret key (octets)
   @return CRYPT_OK if successful
*/
int hmac_init(hmac_state *hmac, int hash, const unsigned char *key, unsigned long keylen)
{
    unsigned char buf[MAXBLOCKSIZE];
    unsigned long hashsize;
    unsigned long i, z;
    int err;

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

    /* valid hash? */
    if ((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }
    hmac->hash = hash;
    hashsize   = hash_descriptor[hash].hashsize;

    /* valid key length? */
    if (keylen == 0) {
        return CRYPT_INVALID_KEYSIZE;
    }

    /* allocate memory for key */
    hmac->key = XMALLOC(LTC_HMAC_BLOCKSIZE);
    if (hmac->key == NULL) {
       return CRYPT_MEM;
    }

    /* (1) make sure we have a large enough key */
    if(keylen > LTC_HMAC_BLOCKSIZE) {
        z = LTC_HMAC_BLOCKSIZE;
        if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) {
           goto LBL_ERR;
        }
        keylen = hashsize;
    } else {
        XMEMCPY(hmac->key, key, (size_t)keylen);
    }

        if(keylen < LTC_HMAC_BLOCKSIZE) {
            zeromem((hmac->key) + keylen, (size_t)(LTC_HMAC_BLOCKSIZE - keylen));
        }

    /* Create the initialization vector for step (3) */
    for(i=0; i < LTC_HMAC_BLOCKSIZE;   i++) {
       buf[i] = hmac->key[i] ^ 0x36;
    }

    /* Pre-pend that to the hash data */
    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;
    }
    goto done;
LBL_ERR:
    /* free the key since we failed */
    XFREE(hmac->key);
done:
#ifdef LTC_CLEAN_STACK
   zeromem(buf, LTC_HMAC_BLOCKSIZE);
#endif
 
   return err;    
}

#endif

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