/* 
   * Cryptographic API.
   *
   * MD4 Message Digest Algorithm (RFC1320).
   *
   * Implementation derived from Andrew Tridgell and Steve French's
   * CIFS MD4 implementation, and the cryptoapi implementation
   * originally based on the public domain implementation written
   * by Colin Plumb in 1993.
   *
   * Copyright (c) Andrew Tridgell 1997-1998.
   * Modified by Steve French (sfrench@us.ibm.com) 2002
   * Copyright (c) Cryptoapi developers.
   * Copyright (c) 2002 David S. Miller (davem@redhat.com)
   * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   *
   * 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 <crypto/internal/hash.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/string.h>
  #include <linux/types.h>
  #include <asm/byteorder.h>
  
  #define MD4_DIGEST_SIZE		16
  #define MD4_HMAC_BLOCK_SIZE	64
  #define MD4_BLOCK_WORDS		16
  #define MD4_HASH_WORDS		4
  
  struct md4_ctx {
  	u32 hash[MD4_HASH_WORDS];
  	u32 block[MD4_BLOCK_WORDS];
  	u64 byte_count;
  };
  
  static inline u32 lshift(u32 x, unsigned int s)
  {
  	x &= 0xFFFFFFFF;
  	return ((x << s) & 0xFFFFFFFF) | (x >> (32 - s));
  }
  
  static inline u32 F(u32 x, u32 y, u32 z)
  {
  	return (x & y) | ((~x) & z);
  }
  
  static inline u32 G(u32 x, u32 y, u32 z)
  {
  	return (x & y) | (x & z) | (y & z);
  }
  
  static inline u32 H(u32 x, u32 y, u32 z)
  {
  	return x ^ y ^ z;
  }
  
  #define ROUND1(a,b,c,d,k,s) (a = lshift(a + F(b,c,d) + k, s))
  #define ROUND2(a,b,c,d,k,s) (a = lshift(a + G(b,c,d) + k + (u32)0x5A827999,s))
  #define ROUND3(a,b,c,d,k,s) (a = lshift(a + H(b,c,d) + k + (u32)0x6ED9EBA1,s))
  
  /* XXX: this stuff can be optimized */
  static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
  {
  	while (words--) {
  		__le32_to_cpus(buf);
  		buf++;
  	}
  }
  
  static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
  {
  	while (words--) {
  		__cpu_to_le32s(buf);
  		buf++;
  	}
  }
  
  static void md4_transform(u32 *hash, u32 const *in)
  {
  	u32 a, b, c, d;
  
  	a = hash[0];
  	b = hash[1];
  	c = hash[2];
  	d = hash[3];
  
  	ROUND1(a, b, c, d, in[0], 3);
  	ROUND1(d, a, b, c, in[1], 7);
  	ROUND1(c, d, a, b, in[2], 11);
  	ROUND1(b, c, d, a, in[3], 19);
  	ROUND1(a, b, c, d, in[4], 3);
  	ROUND1(d, a, b, c, in[5], 7);
  	ROUND1(c, d, a, b, in[6], 11);
  	ROUND1(b, c, d, a, in[7], 19);
  	ROUND1(a, b, c, d, in[8], 3);
  	ROUND1(d, a, b, c, in[9], 7);
  	ROUND1(c, d, a, b, in[10], 11);
  	ROUND1(b, c, d, a, in[11], 19);
  	ROUND1(a, b, c, d, in[12], 3);
  	ROUND1(d, a, b, c, in[13], 7);
  	ROUND1(c, d, a, b, in[14], 11);
  	ROUND1(b, c, d, a, in[15], 19);
  
  	ROUND2(a, b, c, d,in[ 0], 3);
  	ROUND2(d, a, b, c, in[4], 5);
  	ROUND2(c, d, a, b, in[8], 9);
  	ROUND2(b, c, d, a, in[12], 13);
  	ROUND2(a, b, c, d, in[1], 3);
  	ROUND2(d, a, b, c, in[5], 5);
  	ROUND2(c, d, a, b, in[9], 9);
  	ROUND2(b, c, d, a, in[13], 13);
  	ROUND2(a, b, c, d, in[2], 3);
  	ROUND2(d, a, b, c, in[6], 5);
  	ROUND2(c, d, a, b, in[10], 9);
  	ROUND2(b, c, d, a, in[14], 13);
  	ROUND2(a, b, c, d, in[3], 3);
  	ROUND2(d, a, b, c, in[7], 5);
  	ROUND2(c, d, a, b, in[11], 9);
  	ROUND2(b, c, d, a, in[15], 13);
  
  	ROUND3(a, b, c, d,in[ 0], 3);
  	ROUND3(d, a, b, c, in[8], 9);
  	ROUND3(c, d, a, b, in[4], 11);
  	ROUND3(b, c, d, a, in[12], 15);
  	ROUND3(a, b, c, d, in[2], 3);
  	ROUND3(d, a, b, c, in[10], 9);
  	ROUND3(c, d, a, b, in[6], 11);
  	ROUND3(b, c, d, a, in[14], 15);
  	ROUND3(a, b, c, d, in[1], 3);
  	ROUND3(d, a, b, c, in[9], 9);
  	ROUND3(c, d, a, b, in[5], 11);
  	ROUND3(b, c, d, a, in[13], 15);
  	ROUND3(a, b, c, d, in[3], 3);
  	ROUND3(d, a, b, c, in[11], 9);
  	ROUND3(c, d, a, b, in[7], 11);
  	ROUND3(b, c, d, a, in[15], 15);
  
  	hash[0] += a;
  	hash[1] += b;
  	hash[2] += c;
  	hash[3] += d;
  }
  
  static inline void md4_transform_helper(struct md4_ctx *ctx)
  {
  	le32_to_cpu_array(ctx->block, ARRAY_SIZE(ctx->block));
  	md4_transform(ctx->hash, ctx->block);
  }
  
  static int md4_init(struct shash_desc *desc)
  {
  	struct md4_ctx *mctx = shash_desc_ctx(desc);
  
  	mctx->hash[0] = 0x67452301;
  	mctx->hash[1] = 0xefcdab89;
  	mctx->hash[2] = 0x98badcfe;
  	mctx->hash[3] = 0x10325476;
  	mctx->byte_count = 0;
  
  	return 0;
  }
  
  static int md4_update(struct shash_desc *desc, const u8 *data, unsigned int len)
  {
  	struct md4_ctx *mctx = shash_desc_ctx(desc);
  	const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
  
  	mctx->byte_count += len;
  
  	if (avail > len) {
  		memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  		       data, len);
  		return 0;
  	}
  
  	memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  	       data, avail);
  
  	md4_transform_helper(mctx);
  	data += avail;
  	len -= avail;
  
  	while (len >= sizeof(mctx->block)) {
  		memcpy(mctx->block, data, sizeof(mctx->block));
  		md4_transform_helper(mctx);
  		data += sizeof(mctx->block);
  		len -= sizeof(mctx->block);
  	}
  
  	memcpy(mctx->block, data, len);
  
  	return 0;
  }
  
  static int md4_final(struct shash_desc *desc, u8 *out)
  {
  	struct md4_ctx *mctx = shash_desc_ctx(desc);
  	const unsigned int offset = mctx->byte_count & 0x3f;
  	char *p = (char *)mctx->block + offset;
  	int padding = 56 - (offset + 1);
  
  	*p++ = 0x80;
  	if (padding < 0) {
  		memset(p, 0x00, padding + sizeof (u64));
  		md4_transform_helper(mctx);
  		p = (char *)mctx->block;
  		padding = 56;
  	}
  
  	memset(p, 0, padding);
  	mctx->block[14] = mctx->byte_count << 3;
  	mctx->block[15] = mctx->byte_count >> 29;
  	le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
  	                  sizeof(u64)) / sizeof(u32));
  	md4_transform(mctx->hash, mctx->block);
  	cpu_to_le32_array(mctx->hash, ARRAY_SIZE(mctx->hash));
  	memcpy(out, mctx->hash, sizeof(mctx->hash));
  	memset(mctx, 0, sizeof(*mctx));
  
  	return 0;
  }
  
  static struct shash_alg alg = {
  	.digestsize	=	MD4_DIGEST_SIZE,
  	.init		=	md4_init,
  	.update		=	md4_update,
  	.final		=	md4_final,
  	.descsize	=	sizeof(struct md4_ctx),
  	.base		=	{
  		.cra_name	=	"md4",
  		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
  		.cra_blocksize	=	MD4_HMAC_BLOCK_SIZE,
  		.cra_module	=	THIS_MODULE,
  	}
  };
  
  static int __init md4_mod_init(void)
  {
  	return crypto_register_shash(&alg);
  }
  
  static void __exit md4_mod_fini(void)
  {
  	crypto_unregister_shash(&alg);
  }
  
  module_init(md4_mod_init);
  module_exit(md4_mod_fini);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("MD4 Message Digest Algorithm");
  MODULE_ALIAS_CRYPTO("md4");