arch/x86/crypto/salsa20_glue.c

   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  * Also modified to set up the initial state using the generic C code rather
  15  * than in assembly.
  16  *
  17  * This program is free software; you can redistribute it and/or modify it
  18  * under the terms of the GNU General Public License as published by the Free
  19  * Software Foundation; either version 2 of the License, or (at your option)
  20  * any later version.
  21  *
  22  */
  23
  24 #include <asm/unaligned.h>
  25 #include <crypto/internal/skcipher.h>
  26 #include <crypto/salsa20.h>
  27 #include <linux/module.h>
  28
  29 asmlinkage void salsa20_encrypt_bytes(u32 state[16], const u8 *src, u8 *dst,
  30                                       u32 bytes);
  31
  32 static int salsa20_asm_crypt(struct skcipher_request *req)
  33 {
  34         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  35         const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
  36         struct skcipher_walk walk;
  37         u32 state[16];
  38         int err;
  39
  40         err = skcipher_walk_virt(&walk, req, true);
  41
  42         crypto_salsa20_init(state, ctx, walk.iv);
  43
  44         while (walk.nbytes > 0) {
  45                 unsigned int nbytes = walk.nbytes;
  46
  47                 if (nbytes < walk.total)
  48                         nbytes = round_down(nbytes, walk.stride);
  49
  50                 salsa20_encrypt_bytes(state, walk.src.virt.addr,
  51                                       walk.dst.virt.addr, nbytes);
  52                 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  53         }
  54
  55         return err;
  56 }
  57
  58 static struct skcipher_alg alg = {
  59         .base.cra_name          = "salsa20",
  60         .base.cra_driver_name   = "salsa20-asm",
  61         .base.cra_priority      = 200,
  62         .base.cra_blocksize     = 1,
  63         .base.cra_ctxsize       = sizeof(struct salsa20_ctx),
  64         .base.cra_module        = THIS_MODULE,
  65
  66         .min_keysize            = SALSA20_MIN_KEY_SIZE,
  67         .max_keysize            = SALSA20_MAX_KEY_SIZE,
  68         .ivsize                 = SALSA20_IV_SIZE,
  69         .chunksize              = SALSA20_BLOCK_SIZE,
  70         .setkey                 = crypto_salsa20_setkey,
  71         .encrypt                = salsa20_asm_crypt,
  72         .decrypt                = salsa20_asm_crypt,
  73 };
  74
  75 static int __init init(void)
  76 {
  77         return crypto_register_skcipher(&alg);
  78 }
  79
  80 static void __exit fini(void)
  81 {
  82         crypto_unregister_skcipher(&alg);
  83 }
  84
  85 module_init(init);
  86 module_exit(fini);
  87
  88 MODULE_LICENSE("GPL");
  89 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
  90 MODULE_ALIAS_CRYPTO("salsa20");
  91 MODULE_ALIAS_CRYPTO("salsa20-asm");