/*
 *  md4.c : MD4 hash algorithm.
 *
 * Part of the Python Cryptography Toolkit
 *
 * Originally written by: A.M. Kuchling
 *
 * ===================================================================
 * The contents of this file are dedicated to the public domain.  To
 * the extent that dedication to the public domain is not available,
 * everyone is granted a worldwide, perpetual, royalty-free,
 * non-exclusive license to exercise all rights associated with the
 * contents of this file for any purpose whatsoever.
 * No rights are reserved.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * ===================================================================
 *
 */

#include "pycrypto_common.h"
#include <string.h>

#define MODULE_NAME MD4
#define DIGEST_SIZE 16
#define BLOCK_SIZE 64

static char MODULE__doc__[] =
    "MD4 cryptographic hash algorithm.\n"
    "\n"
    "MD4 is specified in RFC1320_ and produces the 128 bit digest of a message.\n"
    "\n"
    "    >>> from Crypto.Hash import MD4\n"
    "    >>>\n"
    "    >>> h = MD4.new()\n"
    "    >>> h.update(b'Hello')\n"
    "    >>> print h.hexdigest()\n"
    "\n"
    "MD4 stand for Message Digest version 4, and it was invented by Rivest in 1990.\n"
    "\n"
    "This algorithm is insecure. Do not use it for new designs.\n"
    "\n"
    ".. _RFC1320: http://tools.ietf.org/html/rfc1320\n"
    "\n"
    ":Variables:\n"
    " block_size\n"
    "    The internal block size of the hash algorithm in bytes.\n"
    " digest_size\n"
    "    The size of the resulting hash in bytes.\n";

typedef uint32_t U32;
typedef uint8_t U8;
#define U32_MAX (U32)4294967295

typedef struct {
	U32 A,B,C,D, count;
	U32 len1, len2;
	U8 buf[64];
} hash_state;

#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

/* ROTATE_LEFT rotates x left n bits */
#define ROL(x, n) (((x) << n) | ((x) >> (32-n) ))

static void 
hash_init (hash_state *ptr)
{
	ptr->A=(U32)0x67452301;
	ptr->B=(U32)0xefcdab89;
	ptr->C=(U32)0x98badcfe;
	ptr->D=(U32)0x10325476;
	ptr->count=ptr->len1=ptr->len2=0;
}

static void
hash_copy(hash_state *src, hash_state *dest)
{
	dest->len1=src->len1;
	dest->len2=src->len2;
	dest->A=src->A;
	dest->B=src->B;
	dest->C=src->C;
	dest->D=src->D;
	dest->count=src->count;  
	memcpy(dest->buf, src->buf, dest->count);
}

static void 
hash_update (hash_state *self, const U8 *buf, U32 len)
{
	U32 L;

	if ((self->len1+(len<<3))<self->len1)
	{
		self->len2++;
	}
	self->len1+=len<< 3;
	self->len2+=len>>29;
	while (len>0) 
	{
		L=(64-self->count) < len ? (64-self->count) : len;
		memcpy(self->buf+self->count, buf, L);
		self->count+=L;
		buf+=L;
		len-=L;
		if (self->count==64) 
		{
			U32 X[16], A, B, C, D;
			int i,j;
			self->count=0;
			for(i=j=0; j<16; i+=4, j++) 
				X[j]=((U32)self->buf[i]       + ((U32)self->buf[i+1]<<8) +
				      ((U32)self->buf[i+2]<<16) + ((U32)self->buf[i+3]<<24));


			A=self->A; B=self->B; C=self->C; D=self->D;

#define function(a,b,c,d,k,s) a=ROL(a+F(b,c,d)+X[k],s);	 
			function(A,B,C,D, 0, 3);
			function(D,A,B,C, 1, 7);
			function(C,D,A,B, 2,11);
			function(B,C,D,A, 3,19);
			function(A,B,C,D, 4, 3);
			function(D,A,B,C, 5, 7);
			function(C,D,A,B, 6,11);
			function(B,C,D,A, 7,19);
			function(A,B,C,D, 8, 3);
			function(D,A,B,C, 9, 7);
			function(C,D,A,B,10,11);
			function(B,C,D,A,11,19);
			function(A,B,C,D,12, 3);
			function(D,A,B,C,13, 7);
			function(C,D,A,B,14,11);
			function(B,C,D,A,15,19);

#undef function	  
#define function(a,b,c,d,k,s) a=ROL(a+G(b,c,d)+X[k]+(U32)0x5a827999,s);	 
			function(A,B,C,D, 0, 3);
			function(D,A,B,C, 4, 5);
			function(C,D,A,B, 8, 9);
			function(B,C,D,A,12,13);
			function(A,B,C,D, 1, 3);
			function(D,A,B,C, 5, 5);
			function(C,D,A,B, 9, 9);
			function(B,C,D,A,13,13);
			function(A,B,C,D, 2, 3);
			function(D,A,B,C, 6, 5);
			function(C,D,A,B,10, 9);
			function(B,C,D,A,14,13);
			function(A,B,C,D, 3, 3);
			function(D,A,B,C, 7, 5);
			function(C,D,A,B,11, 9);
			function(B,C,D,A,15,13);

#undef function	 
#define function(a,b,c,d,k,s) a=ROL(a+H(b,c,d)+X[k]+(U32)0x6ed9eba1,s);	 
			function(A,B,C,D, 0, 3);
			function(D,A,B,C, 8, 9);
			function(C,D,A,B, 4,11);
			function(B,C,D,A,12,15);
			function(A,B,C,D, 2, 3);
			function(D,A,B,C,10, 9);
			function(C,D,A,B, 6,11);
			function(B,C,D,A,14,15);
			function(A,B,C,D, 1, 3);
			function(D,A,B,C, 9, 9);
			function(C,D,A,B, 5,11);
			function(B,C,D,A,13,15);
			function(A,B,C,D, 3, 3);
			function(D,A,B,C,11, 9);
			function(C,D,A,B, 7,11);
			function(B,C,D,A,15,15);

			self->A+=A; self->B+=B; self->C+=C; self->D+=D;
		}
	}
}

static PyObject *
hash_digest (const hash_state *self)
{
	U8 digest[16];
	static U8 s[8];
	U32 padlen, oldlen1, oldlen2;
	hash_state temp;
	static U8 padding[64] = {
		0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
	};

	memcpy(&temp, self, sizeof(hash_state));
	oldlen1=temp.len1; oldlen2=temp.len2;  /* Save current length */
	padlen= (56<=self->count) ? 56-self->count+64: 56-self->count;
	hash_update(&temp, padding, padlen);
	s[0]= oldlen1       & 255;
	s[1]=(oldlen1 >>  8) & 255;
	s[2]=(oldlen1 >> 16) & 255;
	s[3]=(oldlen1 >> 24) & 255;
	s[4]= oldlen2        & 255;
	s[5]=(oldlen2 >>  8) & 255;
	s[6]=(oldlen2 >> 16) & 255;
	s[7]=(oldlen2 >> 24) & 255;
	hash_update(&temp, s, 8);
  
	digest[ 0]= temp.A        & 255;
	digest[ 1]=(temp.A >>  8) & 255;
	digest[ 2]=(temp.A >> 16) & 255;
	digest[ 3]=(temp.A >> 24) & 255;
	digest[ 4]= temp.B        & 255;
	digest[ 5]=(temp.B >>  8) & 255;
	digest[ 6]=(temp.B >> 16) & 255;
	digest[ 7]=(temp.B >> 24) & 255;
	digest[ 8]= temp.C        & 255;
	digest[ 9]=(temp.C >>  8) & 255;
	digest[10]=(temp.C >> 16) & 255;
	digest[11]=(temp.C >> 24) & 255;
	digest[12]= temp.D        & 255;
	digest[13]=(temp.D >>  8) & 255;
	digest[14]=(temp.D >> 16) & 255;
	digest[15]=(temp.D >> 24) & 255;
  
	return PyBytes_FromStringAndSize((char *) digest, 16);
}

#include "hash_template.c"