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

/* Copied from libtomcrypt/src/prngs/sprng.c and modified to
 * use Dropbear's genrandom(). */

/* 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.
 *
 * Tom St Denis, [email protected], http://libtomcrypt.com
 */
#include "includes.h"
#include "dbrandom.h"
#include "ltc_prng.h"

/**
   @file sprng.c
   Secure PRNG, Tom St Denis
*/
   
/* A secure PRNG using the RNG functions.  Basically this is a
 * wrapper that allows you to use a secure RNG as a PRNG
 * in the various other functions.
 */

#if DROPBEAR_LTC_PRNG

/**
  Start the PRNG
  @param prng     [out] The PRNG state to initialize
  @return CRYPT_OK if successful
*/  
int dropbear_prng_start(prng_state* UNUSED(prng))
{
   return CRYPT_OK;  
}

/**
  Add entropy to the PRNG state
  @param in       The data to add
  @param inlen    Length of the data to add
  @param prng     PRNG state to update
  @return CRYPT_OK if successful
*/  
int dropbear_prng_add_entropy(const unsigned char* UNUSED(in), unsigned long UNUSED(inlen), prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  Make the PRNG ready to read from
  @param prng   The PRNG to make active
  @return CRYPT_OK if successful
*/  
int dropbear_prng_ready(prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  Read from the PRNG
  @param out      Destination
  @param outlen   Length of output
  @param prng     The active PRNG to read from
  @return Number of octets read
*/  
unsigned long dropbear_prng_read(unsigned char* out, unsigned long outlen, prng_state* UNUSED(prng))
{
   LTC_ARGCHK(out != NULL);
   genrandom(out, outlen);
   return outlen;
}

/**
  Terminate the PRNG
  @param prng   The PRNG to terminate
  @return CRYPT_OK if successful
*/  
int dropbear_prng_done(prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  Export the PRNG state
  @param out       [out] Destination
  @param outlen    [in/out] Max size and resulting size of the state
  @param prng      The PRNG to export
  @return CRYPT_OK if successful
*/  
int dropbear_prng_export(unsigned char* UNUSED(out), unsigned long* outlen, prng_state* UNUSED(prng))
{
   LTC_ARGCHK(outlen != NULL);

   *outlen = 0;
   return CRYPT_OK;
}
 
/**
  Import a PRNG state
  @param in       The PRNG state
  @param inlen    Size of the state
  @param prng     The PRNG to import
  @return CRYPT_OK if successful
*/  
int dropbear_prng_import(const unsigned char* UNUSED(in), unsigned long UNUSED(inlen), prng_state* UNUSED(prng))
{
   return CRYPT_OK;
}

/**
  PRNG self-test
  @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled
*/  
int dropbear_prng_test(void)
{
   return CRYPT_OK;
}

const struct ltc_prng_descriptor dropbear_prng_desc =
{
    "dropbear_prng", 0,
    dropbear_prng_start,
    dropbear_prng_add_entropy,
    dropbear_prng_ready,
    dropbear_prng_read,
    dropbear_prng_done,
    dropbear_prng_export,
    dropbear_prng_import,
    dropbear_prng_test
};


#endif /* DROPBEAR_LTC_PRNG */