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