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_CRYPTO("salsa20"); 123MODULE_ALIAS_CRYPTO("salsa20-asm"); 124