diff options
Diffstat (limited to 'skein512.c')
| -rw-r--r-- | skein512.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/skein512.c b/skein512.c new file mode 100644 index 00000000..ea78859f --- /dev/null +++ b/skein512.c @@ -0,0 +1,147 @@ +/* skein512.c + + Copyright (C) 2016, 2017, 2018 Niels Möller + + This file is part of GNU Nettle. + + GNU Nettle is free software: you can redistribute it and/or + modify it under the terms of either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at your + option) any later version. + + or both in parallel, as here. + + GNU Nettle 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 + General Public License for more details. + + You should have received copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see http://www.gnu.org/licenses/. +*/ + +#if HAVE_CONFIG_H +# include "config.h" +#endif + +#include <assert.h> +#include <string.h> + +#include "skein.h" + +#include "nettle-write.h" + +void +_skein512_expand(uint64_t keys[_SKEIN512_NKEYS]) +{ + uint64_t sum; + unsigned i; + + for (i = 0, sum = _SKEIN_C240; i < _SKEIN512_LENGTH; i++) + sum ^= keys[i]; + keys[_SKEIN512_LENGTH] = sum; + + /* Repeat keys, for simpler indexing. */ + for (i = _SKEIN512_LENGTH + 1; i < _SKEIN512_NKEYS; i++) + keys[i] = keys[i-9]; +} + +void +skein512_init(struct skein512_ctx *ctx) +{ + static const uint64_t G0[_SKEIN512_LENGTH] = { + 0x4903ADFF749C51CEull, 0x0D95DE399746DF03ull, + 0x8FD1934127C79BCEull, 0x9A255629FF352CB1ull, + 0x5DB62599DF6CA7B0ull, 0xEABE394CA9D5C3F4ull, + 0x991112C71A75B523ull, 0xAE18A40B660FCC33ull, + }; + memcpy (ctx->state, G0, sizeof(G0)); + ctx->count = 0; + ctx->index = 0; +} + +static void +skein512_process_block(struct skein512_ctx *ctx, + unsigned tag, unsigned length, + const uint8_t *data) +{ + /* Expand key */ + uint64_t tweak[_SKEIN_NTWEAK]; + + tag |= ((ctx->count == 0) << 6); + + tweak[0] = (ctx->count << 6) + length; + tweak[1] = (ctx->count >> 58) | ((uint64_t) tag << 56); + _skein512_expand(ctx->state); + + _skein512_block(ctx->state, ctx->state, tweak, data); + + ctx->count++; + + /* Wraparound not handled (limited message size). */ + assert (ctx->count > 0); +} + +void +skein512_update(struct skein512_ctx *ctx, + size_t length, + const uint8_t *data) +{ + if (ctx->index > 0) + { + unsigned left = SKEIN512_BLOCK_SIZE - ctx->index; + if (length <= left) + { + memcpy (ctx->block + ctx->index, data, length); + ctx->index += length; + return; + } + memcpy (ctx->block + ctx->index, data, left); + data += left; + length -= left; + + assert (length > 0); + + skein512_process_block(ctx, 0x30, SKEIN512_BLOCK_SIZE, ctx->block); + } + while (length > SKEIN512_BLOCK_SIZE) + { + skein512_process_block(ctx, 0x30, SKEIN512_BLOCK_SIZE, data); + data += SKEIN512_BLOCK_SIZE; + length -= SKEIN512_BLOCK_SIZE; + } + assert (length <= SKEIN512_BLOCK_SIZE); + memcpy (ctx->block, data, length); + ctx->index = length; +} + +void +skein512_digest(struct skein512_ctx *ctx, + size_t length, + uint8_t *digest) +{ + static const uint8_t zeros[SKEIN512_BLOCK_SIZE]; + + /* FIXME: Should be always true. */ + if (ctx->index > 0 || ctx->count == 0) + { + memset (ctx->block + ctx->index, 0, + SKEIN512_BLOCK_SIZE - ctx->index); + skein512_process_block(ctx, 0xb0, ctx->index, ctx->block); + } + /* Reset count for output processing. */ + ctx->count = 0; + skein512_process_block(ctx, 0xff, 8, zeros); + _nettle_write_le64(length, digest, ctx->state); + + skein512_init(ctx); +} |