From 582c9eeb558ded077506b9f74a02b600e212b780 Mon Sep 17 00:00:00 2001 From: Nikos Mavrogiannopoulos Date: Sun, 17 Mar 2013 14:16:09 +0100 Subject: Added encryption function for 12-round salsa20. --- salsa20r12-crypt.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 salsa20r12-crypt.c (limited to 'salsa20r12-crypt.c') diff --git a/salsa20r12-crypt.c b/salsa20r12-crypt.c new file mode 100644 index 00000000..0c82217b --- /dev/null +++ b/salsa20r12-crypt.c @@ -0,0 +1,74 @@ +/* salsa20r12-crypt.c + * + * The Salsa20 stream cipher. + */ + +/* nettle, low-level cryptographics library + * + * Copyright (C) 2013 Nikos Mavrogiannopoulos + * + * The nettle library is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as published by + * the Free Software Foundation; either version 2.1 of the License, or (at your + * option) any later version. + * + * The nettle library is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public + * License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with the nettle library; see the file COPYING.LIB. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + * MA 02111-1301, USA. + */ + +/* Based on: + salsa20-ref.c version 20051118 + D. J. Bernstein + Public domain. +*/ + +#if HAVE_CONFIG_H +# include "config.h" +#endif + +#include + +#include "salsa20.h" + +#include "macros.h" +#include "memxor.h" + +void +salsa20r12_crypt(struct salsa20_ctx *ctx, + unsigned length, + uint8_t *c, + const uint8_t *m) +{ + uint32_t x[_SALSA20_INPUT_LENGTH]; + + if (!length) + return; + + for (;;) + { + + _salsa20_core (x, ctx->input, 12); + + ctx->input[9] += (++ctx->input[8] == 0); + + /* stopping at 2^70 length per nonce is user's responsibility */ + + if (length <= SALSA20_BLOCK_SIZE) + { + memxor3 (c, m, (uint8_t *) x, length); + return; + } + memxor3 (c, m, (uint8_t *) x, SALSA20_BLOCK_SIZE); + + length -= SALSA20_BLOCK_SIZE; + c += SALSA20_BLOCK_SIZE; + m += SALSA20_BLOCK_SIZE; + } +} -- cgit v1.2.1