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/*
* Cryptographic API.
*
* TEA and Xtended TEA Algorithms
*
* The TEA and Xtended TEA algorithms were developed by David Wheeler
* and Roger Needham at the Computer Laboratory of Cambridge University.
*
* Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <asm/scatterlist.h>
#include <linux/crypto.h>
#define TEA_KEY_SIZE 16
#define TEA_BLOCK_SIZE 8
#define TEA_ROUNDS 32
#define TEA_DELTA 0x9e3779b9
#define XTEA_KEY_SIZE 16
#define XTEA_BLOCK_SIZE 8
#define XTEA_ROUNDS 32
#define XTEA_DELTA 0x9e3779b9
#define u32_in(x) le32_to_cpu(*(const __le32 *)(x))
#define u32_out(to, from) (*(__le32 *)(to) = cpu_to_le32(from))
struct tea_ctx {
u32 KEY[4];
};
struct xtea_ctx {
u32 KEY[4];
};
static int tea_setkey(void *ctx_arg, const u8 *in_key,
unsigned int key_len, u32 *flags)
{
struct tea_ctx *ctx = ctx_arg;
if (key_len != 16)
{
*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
ctx->KEY[0] = u32_in (in_key);
ctx->KEY[1] = u32_in (in_key + 4);
ctx->KEY[2] = u32_in (in_key + 8);
ctx->KEY[3] = u32_in (in_key + 12);
return 0;
}
static void tea_encrypt(void *ctx_arg, u8 *dst, const u8 *src)
{
u32 y, z, n, sum = 0;
u32 k0, k1, k2, k3;
struct tea_ctx *ctx = ctx_arg;
y = u32_in (src);
z = u32_in (src + 4);
k0 = ctx->KEY[0];
k1 = ctx->KEY[1];
k2 = ctx->KEY[2];
k3 = ctx->KEY[3];
n = TEA_ROUNDS;
while (n-- > 0) {
sum += TEA_DELTA;
y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
}
u32_out (dst, y);
u32_out (dst + 4, z);
}
static void tea_decrypt(void *ctx_arg, u8 *dst, const u8 *src)
{
u32 y, z, n, sum;
u32 k0, k1, k2, k3;
struct tea_ctx *ctx = ctx_arg;
y = u32_in (src);
z = u32_in (src + 4);
k0 = ctx->KEY[0];
k1 = ctx->KEY[1];
k2 = ctx->KEY[2];
k3 = ctx->KEY[3];
sum = TEA_DELTA << 5;
n = TEA_ROUNDS;
while (n-- > 0) {
z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
sum -= TEA_DELTA;
}
u32_out (dst, y);
u32_out (dst + 4, z);
}
static int xtea_setkey(void *ctx_arg, const u8 *in_key,
unsigned int key_len, u32 *flags)
{
struct xtea_ctx *ctx = ctx_arg;
if (key_len != 16)
{
*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
ctx->KEY[0] = u32_in (in_key);
ctx->KEY[1] = u32_in (in_key + 4);
ctx->KEY[2] = u32_in (in_key + 8);
ctx->KEY[3] = u32_in (in_key + 12);
return 0;
}
static void xtea_encrypt(void *ctx_arg, u8 *dst, const u8 *src)
{
u32 y, z, sum = 0;
u32 limit = XTEA_DELTA * XTEA_ROUNDS;
struct xtea_ctx *ctx = ctx_arg;
y = u32_in (src);
z = u32_in (src + 4);
while (sum != limit) {
y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3];
sum += XTEA_DELTA;
z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3];
}
u32_out (dst, y);
u32_out (dst + 4, z);
}
static void xtea_decrypt(void *ctx_arg, u8 *dst, const u8 *src)
{
u32 y, z, sum;
struct tea_ctx *ctx = ctx_arg;
y = u32_in (src);
z = u32_in (src + 4);
sum = XTEA_DELTA * XTEA_ROUNDS;
while (sum) {
z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3];
sum -= XTEA_DELTA;
y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3];
}
u32_out (dst, y);
u32_out (dst + 4, z);
}
static struct crypto_alg tea_alg = {
.cra_name = "tea",
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = TEA_BLOCK_SIZE,
.cra_ctxsize = sizeof (struct tea_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(tea_alg.cra_list),
.cra_u = { .cipher = {
.cia_min_keysize = TEA_KEY_SIZE,
.cia_max_keysize = TEA_KEY_SIZE,
.cia_setkey = tea_setkey,
.cia_encrypt = tea_encrypt,
.cia_decrypt = tea_decrypt } }
};
static struct crypto_alg xtea_alg = {
.cra_name = "xtea",
.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
.cra_blocksize = XTEA_BLOCK_SIZE,
.cra_ctxsize = sizeof (struct xtea_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(xtea_alg.cra_list),
.cra_u = { .cipher = {
.cia_min_keysize = XTEA_KEY_SIZE,
.cia_max_keysize = XTEA_KEY_SIZE,
.cia_setkey = xtea_setkey,
.cia_encrypt = xtea_encrypt,
.cia_decrypt = xtea_decrypt } }
};
static int __init init(void)
{
int ret = 0;
ret = crypto_register_alg(&tea_alg);
if (ret < 0)
goto out;
ret = crypto_register_alg(&xtea_alg);
if (ret < 0) {
crypto_unregister_alg(&tea_alg);
goto out;
}
out:
return ret;
}
static void __exit fini(void)
{
crypto_unregister_alg(&tea_alg);
crypto_unregister_alg(&xtea_alg);
}
MODULE_ALIAS("xtea");
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("TEA & XTEA Cryptographic Algorithms");
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