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 // 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
  34 struct salsa20_ctx
  35 {
  36         u32 input[16];
  37 };
  38
  39 asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
  40                                  u32 keysize, u32 ivsize);
  41 asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
  42 asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
  43                                       const u8 *src, u8 *dst, u32 bytes);
  44
  45 static 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
  53 static 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
  90 static 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
 113 static int __init init(void)
 114 {
 115         return crypto_register_alg(&alg);
 116 }
 117
 118 static void __exit fini(void)
 119 {
 120         crypto_unregister_alg(&alg);
 121 }
 122
 123 module_init(init);
 124 module_exit(fini);
 125
 126 MODULE_LICENSE("GPL");
 127 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
 128 MODULE_ALIAS("salsa20");
 129 MODULE_ALIAS("salsa20-asm");