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

#define MODULE_NAME MD2
#define DIGEST_SIZE 16
#define BLOCK_SIZE 64

static char MODULE__doc__[] =
    "MD2 cryptographic hash algorithm.\n"
    "\n"
    "MD2 is specified in RFC1319_ and it produces the 128 bit digest of a message.\n"
    "\n"
    "    >>> from Crypto.Hash import MD2\n"
    "    >>>\n"
    "    >>> h = MD2.new()\n"
    "    >>> h.update(b'Hello')\n"
    "    >>> print h.hexdigest()\n"
    "\n"
    "MD2 stand for Message Digest version 2, and it was invented by Rivest in 1989.\n"
    "\n"
    "This algorithm is both slow and insecure. Do not use it for new designs.\n"
    "\n"
    ".. _RFC1319: http://tools.ietf.org/html/rfc1319\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 uint8_t U8;
typedef uint32_t U32;

typedef struct {
	U8 C[16], X[48];
	unsigned 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;
	unsigned 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"