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
  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("salsa20");
 123MODULE_ALIAS("salsa20-asm");
 124