/* 
   * Cryptographic API.
   *

   * TEA, XTEA, and XETA crypto alogrithms

   *
   * The TEA and Xtended TEA algorithms were developed by David Wheeler 
   * and Roger Needham at the Computer Laboratory of Cambridge University.
   *

   * Due to the order of evaluation in XTEA many people have incorrectly
   * implemented it.  XETA (XTEA in the wrong order), exists for
   * compatibility with these implementations.
   *

   * 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/byteorder.h>

  #include <linux/crypto.h>

  #include <linux/types.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

  struct tea_ctx {
  	u32 KEY[4];
  };
  
  struct xtea_ctx {
  	u32 KEY[4];
  };

  static int tea_setkey(struct crypto_tfm *tfm, const u8 *in_key,

  		      unsigned int key_len)

  {
  	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *key = (const __le32 *)in_key;

  	ctx->KEY[0] = le32_to_cpu(key[0]);
  	ctx->KEY[1] = le32_to_cpu(key[1]);
  	ctx->KEY[2] = le32_to_cpu(key[2]);
  	ctx->KEY[3] = le32_to_cpu(key[3]);

  
  	return 0; 
  
  }

  static void tea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, n, sum = 0;
  	u32 k0, k1, k2, k3;

  	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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);
  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static void tea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, n, sum;
  	u32 k0, k1, k2, k3;

  	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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;
  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static int xtea_setkey(struct crypto_tfm *tfm, const u8 *in_key,

  		       unsigned int key_len)

  {
  	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *key = (const __le32 *)in_key;

  	ctx->KEY[0] = le32_to_cpu(key[0]);
  	ctx->KEY[1] = le32_to_cpu(key[1]);
  	ctx->KEY[2] = le32_to_cpu(key[2]);
  	ctx->KEY[3] = le32_to_cpu(key[3]);

  
  	return 0; 
  
  }

  static void xtea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, sum = 0;
  	u32 limit = XTEA_DELTA * XTEA_ROUNDS;

  	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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]); 

  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static void xtea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, sum;

  	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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]);
  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static void xeta_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, sum = 0;
  	u32 limit = XTEA_DELTA * XTEA_ROUNDS;

  	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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];
  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static void xeta_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  {

  	u32 y, z, sum;

  	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);

  	const __le32 *in = (const __le32 *)src;
  	__le32 *out = (__le32 *)dst;

  	y = le32_to_cpu(in[0]);
  	z = le32_to_cpu(in[1]);

  
  	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];
  	}
  	

  	out[0] = cpu_to_le32(y);
  	out[1] = cpu_to_le32(z);

  }

  static struct crypto_alg tea_algs[3] = { {

  	.cra_name		=	"tea",
  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	TEA_BLOCK_SIZE,
  	.cra_ctxsize		=	sizeof (struct tea_ctx),

  	.cra_alignmask		=	3,

  	.cra_module		=	THIS_MODULE,

  	.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 } }

  }, {

  	.cra_name		=	"xtea",
  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	XTEA_BLOCK_SIZE,
  	.cra_ctxsize		=	sizeof (struct xtea_ctx),

  	.cra_alignmask		=	3,

  	.cra_module		=	THIS_MODULE,

  	.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 } }

  }, {

  	.cra_name		=	"xeta",
  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	XTEA_BLOCK_SIZE,
  	.cra_ctxsize		=	sizeof (struct xtea_ctx),

  	.cra_alignmask		=	3,

  	.cra_module		=	THIS_MODULE,

  	.cra_u			=	{ .cipher = {
  	.cia_min_keysize	=	XTEA_KEY_SIZE,
  	.cia_max_keysize	=	XTEA_KEY_SIZE,
  	.cia_setkey		= 	xtea_setkey,
  	.cia_encrypt		=	xeta_encrypt,
  	.cia_decrypt		=	xeta_decrypt } }

  } };

  static int __init tea_mod_init(void)

  {

  	return crypto_register_algs(tea_algs, ARRAY_SIZE(tea_algs));

  }

  static void __exit tea_mod_fini(void)

  {

  	crypto_unregister_algs(tea_algs, ARRAY_SIZE(tea_algs));

  }

  MODULE_ALIAS_CRYPTO("tea");

  MODULE_ALIAS_CRYPTO("xtea");
  MODULE_ALIAS_CRYPTO("xeta");

  module_init(tea_mod_init);
  module_exit(tea_mod_fini);

  
  MODULE_LICENSE("GPL");

  MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms");