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  * 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 struct salsa20_ctx
  30 {
  31         u32 input[16];
  32 };
  33
  34 asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
  35                                  u32 keysize, u32 ivsize);
  36 asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
  37 asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
  38                                       const u8 *src, u8 *dst, u32 bytes);
  39
  40 static 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
  48 static 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
  85 static 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
 107 static int __init init(void)
 108 {
 109         return crypto_register_alg(&alg);
 110 }
 111
 112 static void __exit fini(void)
 113 {
 114         crypto_unregister_alg(&alg);
 115 }
 116
 117 module_init(init);
 118 module_exit(fini);
 119
 120 MODULE_LICENSE("GPL");
 121 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
 122 MODULE_ALIAS_CRYPTO("salsa20");
 123 MODULE_ALIAS_CRYPTO("salsa20-asm");