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/*
* Glue code for optimized assembly version of Salsa20.
*
* Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
*
* The assembly codes are public domain assembly codes written by Daniel. J.
* Bernstein <djb@cr.yp.to>. The codes are modified to include indentation
* and to remove extraneous comments and functions that are not needed.
* - i586 version, renamed as salsa20-i586-asm_32.S
* available from <http://cr.yp.to/snuffle/salsa20/x86-pm/salsa20.s>
* - x86-64 version, renamed as salsa20-x86_64-asm_64.S
* available from <http://cr.yp.to/snuffle/salsa20/amd64-3/salsa20.s>
*
* 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 <crypto/algapi.h>
#include <linux/module.h>
#include <linux/crypto.h>
#define SALSA20_IV_SIZE 8U
#define SALSA20_MIN_KEY_SIZE 16U
#define SALSA20_MAX_KEY_SIZE 32U
struct salsa20_ctx
{
u32 input[16];
};
asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
u32 keysize, u32 ivsize);
asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
const u8 *src, u8 *dst, u32 bytes);
static int setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keysize)
{
struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
salsa20_keysetup(ctx, key, keysize*8, SALSA20_IV_SIZE*8);
return 0;
}
static int encrypt(struct blkcipher_desc *desc,
struct scatterlist *dst, struct scatterlist *src,
unsigned int nbytes)
{
struct blkcipher_walk walk;
struct crypto_blkcipher *tfm = desc->tfm;
struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
int err;
blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt_block(desc, &walk, 64);
salsa20_ivsetup(ctx, walk.iv);
if (likely(walk.nbytes == nbytes))
{
salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
walk.dst.virt.addr, nbytes);
return blkcipher_walk_done(desc, &walk, 0);
}
while (walk.nbytes >= 64) {
salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
walk.dst.virt.addr,
walk.nbytes - (walk.nbytes % 64));
err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
}
if (walk.nbytes) {
salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
walk.dst.virt.addr, walk.nbytes);
err = blkcipher_walk_done(desc, &walk, 0);
}
return err;
}
static struct crypto_alg alg = {
.cra_name = "salsa20",
.cra_driver_name = "salsa20-asm",
.cra_priority = 200,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_type = &crypto_blkcipher_type,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct salsa20_ctx),
.cra_alignmask = 3,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.setkey = setkey,
.encrypt = encrypt,
.decrypt = encrypt,
.min_keysize = SALSA20_MIN_KEY_SIZE,
.max_keysize = SALSA20_MAX_KEY_SIZE,
.ivsize = SALSA20_IV_SIZE,
}
}
};
static int __init init(void)
{
return crypto_register_alg(&alg);
}
static void __exit fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
MODULE_ALIAS("salsa20");
MODULE_ALIAS("salsa20-asm");
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