LXR linux/arch/x86/crypto/salsa20

   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
  29// use the ECRYPT_* function names
  30#define salsa20_keysetup        ECRYPT_keysetup
  31#define salsa20_ivsetup         ECRYPT_ivsetup
  32#define salsa20_encrypt_bytes   ECRYPT_encrypt_bytes
  33
  34struct salsa20_ctx
  35{
  36        u32 input[16];
  37};
  38
  39asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
  40                                 u32 keysize, u32 ivsize);
  41asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
  42asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
  43                                      const u8 *src, u8 *dst, u32 bytes);
  44
  45static int setkey(struct crypto_tfm *tfm, const u8 *key,
  46                  unsigned int keysize)
  47{
  48        struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
  49        salsa20_keysetup(ctx, key, keysize*8, SALSA20_IV_SIZE*8);
  50        return 0;
  51}
  52
  53static int encrypt(struct blkcipher_desc *desc,
  54                   struct scatterlist *dst, struct scatterlist *src,
  55                   unsigned int nbytes)
  56{
  57        struct blkcipher_walk walk;
  58        struct crypto_blkcipher *tfm = desc->tfm;
  59        struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
  60        int err;
  61
  62        blkcipher_walk_init(&walk, dst, src, nbytes);
  63        err = blkcipher_walk_virt_block(desc, &walk, 64);
  64
  65        salsa20_ivsetup(ctx, walk.iv);
  66
  67        if (likely(walk.nbytes == nbytes))
  68        {
  69                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
  70                                      walk.dst.virt.addr, nbytes);
  71                return blkcipher_walk_done(desc, &walk, 0);
  72        }
  73
  74        while (walk.nbytes >= 64) {
  75                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
  76                                      walk.dst.virt.addr,
  77                                      walk.nbytes - (walk.nbytes % 64));
  78                err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
  79        }
  80
  81        if (walk.nbytes) {
  82                salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
  83                                      walk.dst.virt.addr, walk.nbytes);
  84                err = blkcipher_walk_done(desc, &walk, 0);
  85        }
  86
  87        return err;
  88}
  89
  90static struct crypto_alg alg = {
  91        .cra_name           =   "salsa20",
  92        .cra_driver_name    =   "salsa20-asm",
  93        .cra_priority       =   200,
  94        .cra_flags          =   CRYPTO_ALG_TYPE_BLKCIPHER,
  95        .cra_type           =   &crypto_blkcipher_type,
  96        .cra_blocksize      =   1,
  97        .cra_ctxsize        =   sizeof(struct salsa20_ctx),
  98        .cra_alignmask      =   3,
  99        .cra_module         =   THIS_MODULE,
 100        .cra_list           =   LIST_HEAD_INIT(alg.cra_list),
 101        .cra_u              =   {
 102                .blkcipher = {
 103                        .setkey         =   setkey,
 104                        .encrypt        =   encrypt,
 105                        .decrypt        =   encrypt,
 106                        .min_keysize    =   SALSA20_MIN_KEY_SIZE,
 107                        .max_keysize    =   SALSA20_MAX_KEY_SIZE,
 108                        .ivsize         =   SALSA20_IV_SIZE,
 109                }
 110        }
 111};
 112
 113static int __init init(void)
 114{
 115        return crypto_register_alg(&alg);
 116}
 117
 118static void __exit fini(void)
 119{
 120        crypto_unregister_alg(&alg);
 121}
 122
 123module_init(init);
 124module_exit(fini);
 125
 126MODULE_LICENSE("GPL");
 127MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
 128MODULE_ALIAS("salsa20");
 129MODULE_ALIAS("salsa20-asm");
 130