+++ /dev/null
-/*
- * Salsa20: Salsa20 stream cipher algorithm
- *
- * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
- *
- * Derived from:
- * - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
- *
- * Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
- * Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
- * More information about eSTREAM and Salsa20 can be found here:
- * https://www.ecrypt.eu.org/stream/
- * https://cr.yp.to/snuffle.html
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of 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.
- *
- */
-
-#include <asm/unaligned.h>
-#include <crypto/internal/skcipher.h>
-#include <linux/module.h>
-
-#define SALSA20_IV_SIZE 8
-#define SALSA20_MIN_KEY_SIZE 16
-#define SALSA20_MAX_KEY_SIZE 32
-#define SALSA20_BLOCK_SIZE 64
-
-struct salsa20_ctx {
- u32 initial_state[16];
-};
-
-static void salsa20_block(u32 *state, __le32 *stream)
-{
- u32 x[16];
- int i;
-
- memcpy(x, state, sizeof(x));
-
- for (i = 0; i < 20; i += 2) {
- x[ 4] ^= rol32((x[ 0] + x[12]), 7);
- x[ 8] ^= rol32((x[ 4] + x[ 0]), 9);
- x[12] ^= rol32((x[ 8] + x[ 4]), 13);
- x[ 0] ^= rol32((x[12] + x[ 8]), 18);
- x[ 9] ^= rol32((x[ 5] + x[ 1]), 7);
- x[13] ^= rol32((x[ 9] + x[ 5]), 9);
- x[ 1] ^= rol32((x[13] + x[ 9]), 13);
- x[ 5] ^= rol32((x[ 1] + x[13]), 18);
- x[14] ^= rol32((x[10] + x[ 6]), 7);
- x[ 2] ^= rol32((x[14] + x[10]), 9);
- x[ 6] ^= rol32((x[ 2] + x[14]), 13);
- x[10] ^= rol32((x[ 6] + x[ 2]), 18);
- x[ 3] ^= rol32((x[15] + x[11]), 7);
- x[ 7] ^= rol32((x[ 3] + x[15]), 9);
- x[11] ^= rol32((x[ 7] + x[ 3]), 13);
- x[15] ^= rol32((x[11] + x[ 7]), 18);
- x[ 1] ^= rol32((x[ 0] + x[ 3]), 7);
- x[ 2] ^= rol32((x[ 1] + x[ 0]), 9);
- x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
- x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
- x[ 6] ^= rol32((x[ 5] + x[ 4]), 7);
- x[ 7] ^= rol32((x[ 6] + x[ 5]), 9);
- x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
- x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
- x[11] ^= rol32((x[10] + x[ 9]), 7);
- x[ 8] ^= rol32((x[11] + x[10]), 9);
- x[ 9] ^= rol32((x[ 8] + x[11]), 13);
- x[10] ^= rol32((x[ 9] + x[ 8]), 18);
- x[12] ^= rol32((x[15] + x[14]), 7);
- x[13] ^= rol32((x[12] + x[15]), 9);
- x[14] ^= rol32((x[13] + x[12]), 13);
- x[15] ^= rol32((x[14] + x[13]), 18);
- }
-
- for (i = 0; i < 16; i++)
- stream[i] = cpu_to_le32(x[i] + state[i]);
-
- if (++state[8] == 0)
- state[9]++;
-}
-
-static void salsa20_docrypt(u32 *state, u8 *dst, const u8 *src,
- unsigned int bytes)
-{
- __le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)];
-
- while (bytes >= SALSA20_BLOCK_SIZE) {
- salsa20_block(state, stream);
- crypto_xor_cpy(dst, src, (const u8 *)stream,
- SALSA20_BLOCK_SIZE);
- bytes -= SALSA20_BLOCK_SIZE;
- dst += SALSA20_BLOCK_SIZE;
- src += SALSA20_BLOCK_SIZE;
- }
- if (bytes) {
- salsa20_block(state, stream);
- crypto_xor_cpy(dst, src, (const u8 *)stream, bytes);
- }
-}
-
-static void salsa20_init(u32 *state, const struct salsa20_ctx *ctx,
- const u8 *iv)
-{
- memcpy(state, ctx->initial_state, sizeof(ctx->initial_state));
- state[6] = get_unaligned_le32(iv + 0);
- state[7] = get_unaligned_le32(iv + 4);
-}
-
-static int salsa20_setkey(struct crypto_skcipher *tfm, const u8 *key,
- unsigned int keysize)
-{
- static const char sigma[16] = "expand 32-byte k";
- static const char tau[16] = "expand 16-byte k";
- struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
- const char *constants;
-
- if (keysize != SALSA20_MIN_KEY_SIZE &&
- keysize != SALSA20_MAX_KEY_SIZE)
- return -EINVAL;
-
- ctx->initial_state[1] = get_unaligned_le32(key + 0);
- ctx->initial_state[2] = get_unaligned_le32(key + 4);
- ctx->initial_state[3] = get_unaligned_le32(key + 8);
- ctx->initial_state[4] = get_unaligned_le32(key + 12);
- if (keysize == 32) { /* recommended */
- key += 16;
- constants = sigma;
- } else { /* keysize == 16 */
- constants = tau;
- }
- ctx->initial_state[11] = get_unaligned_le32(key + 0);
- ctx->initial_state[12] = get_unaligned_le32(key + 4);
- ctx->initial_state[13] = get_unaligned_le32(key + 8);
- ctx->initial_state[14] = get_unaligned_le32(key + 12);
- ctx->initial_state[0] = get_unaligned_le32(constants + 0);
- ctx->initial_state[5] = get_unaligned_le32(constants + 4);
- ctx->initial_state[10] = get_unaligned_le32(constants + 8);
- ctx->initial_state[15] = get_unaligned_le32(constants + 12);
-
- /* space for the nonce; it will be overridden for each request */
- ctx->initial_state[6] = 0;
- ctx->initial_state[7] = 0;
-
- /* initial block number */
- ctx->initial_state[8] = 0;
- ctx->initial_state[9] = 0;
-
- return 0;
-}
-
-static int salsa20_crypt(struct skcipher_request *req)
-{
- struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
- const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
- struct skcipher_walk walk;
- u32 state[16];
- int err;
-
- err = skcipher_walk_virt(&walk, req, false);
-
- salsa20_init(state, ctx, req->iv);
-
- while (walk.nbytes > 0) {
- unsigned int nbytes = walk.nbytes;
-
- if (nbytes < walk.total)
- nbytes = round_down(nbytes, walk.stride);
-
- salsa20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
- nbytes);
- err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
- }
-
- return err;
-}
-
-static struct skcipher_alg alg = {
- .base.cra_name = "salsa20",
- .base.cra_driver_name = "salsa20-generic",
- .base.cra_priority = 100,
- .base.cra_blocksize = 1,
- .base.cra_ctxsize = sizeof(struct salsa20_ctx),
- .base.cra_module = THIS_MODULE,
-
- .min_keysize = SALSA20_MIN_KEY_SIZE,
- .max_keysize = SALSA20_MAX_KEY_SIZE,
- .ivsize = SALSA20_IV_SIZE,
- .chunksize = SALSA20_BLOCK_SIZE,
- .setkey = salsa20_setkey,
- .encrypt = salsa20_crypt,
- .decrypt = salsa20_crypt,
-};
-
-static int __init salsa20_generic_mod_init(void)
-{
- return crypto_register_skcipher(&alg);
-}
-
-static void __exit salsa20_generic_mod_fini(void)
-{
- crypto_unregister_skcipher(&alg);
-}
-
-subsys_initcall(salsa20_generic_mod_init);
-module_exit(salsa20_generic_mod_fini);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
-MODULE_ALIAS_CRYPTO("salsa20");
-MODULE_ALIAS_CRYPTO("salsa20-generic");
projects / linux-2.6-block.git / blobdiff