/*
 *  md2.c : MD2 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 <string.h>
#include "Python.h"
#include "pycrypto_compat.h"

#define MODULE_NAME _MD2
#define DIGEST_SIZE 16
#define BLOCK_SIZE 64

/**
 * id-md2      OBJECT IDENTIFIER ::= {
 * 			iso(1) member-body(2) us(840) rsadsi(113549)
 * 			digestAlgorithm(2) 2
 * 			}
 */
static const char md2_oid[] = { 0x06, 0x08, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x02 };

#define DER_OID 		((void*)&md2_oid)
#define DER_OID_SIZE		(sizeof md2_oid)

typedef unsigned char U8;
typedef unsigned int U32;

typedef struct {
	U8 C[16], X[48];
	int count;
	U8 buf[16];
} hash_state;

static void hash_init (hash_state *ptr)
{
	memset(ptr->X, 0, 48);
	memset(ptr->C, 0, 16);
	ptr->count=0;
}

static U8 S[256] = {
	41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
	19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
	76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
	138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
	245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
	148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
	39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
	181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
	150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
	112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
	96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
	85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
	234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
	129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
	8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
	203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
	166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
	31, 26, 219, 153, 141, 51, 159, 17, 131, 20
};

static void
hash_copy(hash_state *src, hash_state *dest)
{
	dest->count=src->count;  
	memcpy(dest->buf, src->buf, dest->count);
	memcpy(dest->X, src->X, 48);
	memcpy(dest->C, src->C, 16);
}


static void hash_update (hash_state *self, const U8 *buf, U32 len)
{
	U32 L;
	while (len) 
	{
		L=(16-self->count) < len ? (16-self->count) : len;
		memcpy(self->buf+self->count, buf, L);
		self->count+=L;
		buf+=L;
		len-=L;
		if (self->count==16) 
		{
			U8 t;
			int i,j;
	  
			self->count=0;
			memcpy(self->X+16, self->buf, 16);
			t=self->C[15];
			for(i=0; i<16; i++)
			{
				self->X[32+i]=self->X[16+i]^self->X[i];
				t=self->C[i]^=S[self->buf[i]^t];
			}
	  
			t=0;
			for(i=0; i<18; i++)
			{
				for(j=0; j<48; j++)
					t=self->X[j]^=S[t];
				t=(t+i) & 0xFF;
			}
		}
	}
}

static PyObject *
hash_digest (const hash_state *self)
{
	U8 padding[16];
	U32 padlen;
	hash_state temp;
	int i;
  
	memcpy(&temp, self, sizeof(hash_state));
	padlen= 16-self->count;
	for(i=0; i<padlen; i++) padding[i]=padlen;
	hash_update(&temp, padding, padlen);
	hash_update(&temp, temp.C, 16);
	return PyBytes_FromStringAndSize((char *) temp.X, 16);
}

#include "hash_template.c"