1/*
  2 * Glue code for optimized assembly version of  Salsa20.
  3 *
  4 * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
  5 *
  6 * The assembly codes are public domain assembly codes written by Daniel. J.
  7 * Bernstein <djb@cr.yp.to>. The codes are modified to include indentation
  8 * and to remove extraneous comments and functions that are not needed.
  9 * - i586 version, renamed as salsa20-i586-asm_32.S
 10 *   available from <http://cr.yp.to/snuffle/salsa20/x86-pm/salsa20.s>
 11 * - x86-64 version, renamed as salsa20-x86_64-asm_64.S
 12 *   available from <http://cr.yp.to/snuffle/salsa20/amd64-3/salsa20.s>
 13 *
 14 * This program is free software; you can redistribute it and/or modify it
 15 * under the terms of the GNU General Public License as published by the Free
 16 * Software Foundation; either version 2 of the License, or (at your option)
 17 * any later version.
 18 *
 19 */
 20
 21#include <crypto/algapi.h>
 22#include <linux/module.h>
 23#include <linux/crypto.h>
 24
 25#define SALSA20_IV_SIZE        8U
 26#define SALSA20_MIN_KEY_SIZE  16U
 27#define SALSA20_MAX_KEY_SIZE  32U
 28
 29struct salsa20_ctx
 30{
 31	u32 input[16];
 32};
 33
 34asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
 35				 u32 keysize, u32 ivsize);
 36asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
 37asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
 38				      const u8 *src, u8 *dst, u32 bytes);
 39
 40static int setkey(struct crypto_tfm *tfm, const u8 *key,
 41		  unsigned int keysize)
 42{
 43	struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
 44	salsa20_keysetup(ctx, key, keysize*8, SALSA20_IV_SIZE*8);
 45	return 0;
 46}
 47
 48static int encrypt(struct blkcipher_desc *desc,
 49		   struct scatterlist *dst, struct scatterlist *src,
 50		   unsigned int nbytes)
 51{
 52	struct blkcipher_walk walk;
 53	struct crypto_blkcipher *tfm = desc->tfm;
 54	struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
 55	int err;
 56
 57	blkcipher_walk_init(&walk, dst, src, nbytes);
 58	err = blkcipher_walk_virt_block(desc, &walk, 64);
 59
 60	salsa20_ivsetup(ctx, walk.iv);
 61
 62	if (likely(walk.nbytes == nbytes))
 63	{
 64		salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
 65				      walk.dst.virt.addr, nbytes);
 66		return blkcipher_walk_done(desc, &walk, 0);
 67	}
 68
 69	while (walk.nbytes >= 64) {
 70		salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
 71				      walk.dst.virt.addr,
 72				      walk.nbytes - (walk.nbytes % 64));
 73		err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
 74	}
 75
 76	if (walk.nbytes) {
 77		salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
 78				      walk.dst.virt.addr, walk.nbytes);
 79		err = blkcipher_walk_done(desc, &walk, 0);
 80	}
 81
 82	return err;
 83}
 84
 85static struct crypto_alg alg = {
 86	.cra_name           =   "salsa20",
 87	.cra_driver_name    =   "salsa20-asm",
 88	.cra_priority       =   200,
 89	.cra_flags          =   CRYPTO_ALG_TYPE_BLKCIPHER,
 90	.cra_type           =   &crypto_blkcipher_type,
 91	.cra_blocksize      =   1,
 92	.cra_ctxsize        =   sizeof(struct salsa20_ctx),
 93	.cra_alignmask      =	3,
 94	.cra_module         =   THIS_MODULE,
 95	.cra_u              =   {
 96		.blkcipher = {
 97			.setkey         =   setkey,
 98			.encrypt        =   encrypt,
 99			.decrypt        =   encrypt,
100			.min_keysize    =   SALSA20_MIN_KEY_SIZE,
101			.max_keysize    =   SALSA20_MAX_KEY_SIZE,
102			.ivsize         =   SALSA20_IV_SIZE,
103		}
104	}
105};
106
107static int __init init(void)
108{
109	return crypto_register_alg(&alg);
110}
111
112static void __exit fini(void)
113{
114	crypto_unregister_alg(&alg);
115}
116
117module_init(init);
118module_exit(fini);
119
120MODULE_LICENSE("GPL");
121MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
122MODULE_ALIAS_CRYPTO("salsa20");
123MODULE_ALIAS_CRYPTO("salsa20-asm");