//
//	cook - file construction tool
//	Copyright (C) 1994, 1995, 1999, 2003-2008 Peter Miller
//
//	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 3 of the License, or
//	(at your option) any later version.
//
//	This program is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//	GNU General Public License for more details.
//
//	You should have received a copy of the GNU General Public License
//	along with this program. If not, see
//	<http://www.gnu.org/licenses/>.
//
// Derived from code marked
//	derived from RSADSI MD5 Message-Digest Algorithm
//	Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991.
//      All rights reserved.
//
//	License to copy and use this software is granted provided that it
//	is identified as the "RSA Data Security, Inc. MD5 Message-Digest
//	Algorithm" in all material mentioning or referencing this software
//	or this function.
//
//	License is also granted to make and use derivative works provided
//	that such works are identified as "derived from the RSA Data
//	Security, Inc. MD5 Message-Digest Algorithm" in all material
//	mentioning or referencing the derived work.
//
//	RSA Data Security, Inc. makes no representations concerning either
//	the merchantability of this software or the suitability of this
//	software for any particular purpose. It is provided "as is"
//	without express or implied warranty of any kind.
//
//	These notices must be retained in any copies of any part of this
//	documentation and/or software.
//

#include <common/ac/inttypes.h>
#include <common/ac/stdint.h>
#include <common/ac/stdio.h>
#include <common/ac/string.h>

#include <common/fp/md5.h>

#define MD5_HASH_LEN 16

struct md5_ty
{
    FINGERPRINT_BASE_CLASS
    unsigned long   state[4];
    unsigned long   count[2];
    unsigned char   buffer[64];
};


//
// Constants for MD5Transform routine.
//
#define S11		7
#define S12		12
#define S13		17
#define S14		22
#define S21		5
#define S22		9
#define S23		14
#define S24		20
#define S31		4
#define S32		11
#define S33		16
#define S34		23
#define S41		6
#define S42		10
#define S43		15
#define S44		21

static unsigned char PADDING[64] =
{
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

//
// F, G, H and I are basic MD5 functions.
//
#define F(x, y, z)	(((x)&(y)) | ((~x)&(z)))
#define G(x, y, z)	(((x)&(z)) | ((y)&(~z)))
#define H(x, y, z)	((x) ^ (y) ^ (z))
#define I(x, y, z)	((y) ^ ((x) | (~z)))

//
// ROTATE_LEFT rotates x left n bits.
//
#define ROTATE_LEFT(x, n) \
    ((uint32_t)((x) << (n)) | ((uint32_t)(x) >> (32 - (n))))

//
// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.
//
#define FF(a, b, c, d, x, s, ac)					\
    do {								\
       	(a) += F((b), (c), (d)) + (x) + (unsigned long)(ac);		\
       	(a) = ROTATE_LEFT((a), (s));					\
       	(a) += (b);							\
    } while(0)
#define GG(a, b, c, d, x, s, ac)					\
    do {								\
       	(a) += G((b), (c), (d)) + (x) + (unsigned long)(ac);		\
       	(a) = ROTATE_LEFT((a), (s));					\
       	(a) += (b);							\
    } while(0)
#define HH(a, b, c, d, x, s, ac)					\
    do {								\
       	(a) += H((b), (c), (d)) + (x) + (unsigned long)(ac);		\
       	(a) = ROTATE_LEFT((a), (s));					\
       	(a) += (b);							\
    } while(0)
#define II(a, b, c, d, x, s, ac)					\
    do {								\
       	(a) += I((b), (c), (d)) + (x) + (unsigned long)(ac);		\
       	(a) = ROTATE_LEFT((a), (s));					\
       	(a) += (b);							\
    } while(0)


//
// MD5 initialization. Begins an MD5 operation, writing a new context.
//

static void
reset(md5_ty *context)
{
    context->count[0] = 0;
    context->count[1] = 0;

    //
    // Load magic initialization constants.
    //
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}


static void
md5_constructor(fingerprint_ty *p)
{
    md5_ty	    *context;

    context = (md5_ty *)p;
    reset(context);
}


static void
md5_destructor(fingerprint_ty *)
{
}


//
// Encodes input (unsigned long) into output (unsigned char).
// Assumes len is a multiple of 4.
//

static void
Encode(unsigned char *output, unsigned long *input, unsigned int len)
{
    unsigned int    i;
    unsigned int    j;

    for (i = 0, j = 0; j < len; i++, j += 4)
    {
	output[j] = (unsigned char)input[i];
	output[j + 1] = (unsigned char)(input[i] >> 8);
	output[j + 2] = (unsigned char)(input[i] >> 16);
	output[j + 3] = (unsigned char)(input[i] >> 24);
    }
}


//
// Decodes input (unsigned char) into output (unsigned long).
// Assumes len is a multiple of 4.
//

static void
Decode(unsigned long *output, unsigned char *input, unsigned int len)
{
    unsigned int    i;
    unsigned int    j;

    for (i = 0, j = 0; j < len; i++, j += 4)
    {
	output[i] =
	    (
		((unsigned long)input[j])
	    |
		(((unsigned long)input[j + 1]) << 8)
	    |
		(((unsigned long)input[j + 2]) << 16)
	    |
		(((unsigned long)input[j + 3]) << 24)
	    );
    }
}


//
// MD5 basic transformation. Transforms state based on block.
//

static void
MD5Transform(unsigned long state[4], unsigned char block[64])
{
    unsigned long   a		= state[0],
		    b		= state[1],
		    c		= state[2],
		    d		= state[3];
    unsigned long   x[16];

    Decode(x, block, 64);
    // Round 1
    FF(a, b, c, d, x[0], S11, 0xd76aa478); // 1
    FF(d, a, b, c, x[1], S12, 0xe8c7b756); // 2
    FF(c, d, a, b, x[2], S13, 0x242070db); // 3
    FF(b, c, d, a, x[3], S14, 0xc1bdceee); // 4
    FF(a, b, c, d, x[4], S11, 0xf57c0faf); // 5
    FF(d, a, b, c, x[5], S12, 0x4787c62a); // 6
    FF(c, d, a, b, x[6], S13, 0xa8304613); // 7
    FF(b, c, d, a, x[7], S14, 0xfd469501); // 8
    FF(a, b, c, d, x[8], S11, 0x698098d8); // 9
    FF(d, a, b, c, x[9], S12, 0x8b44f7af); // 10
    FF(c, d, a, b, x[10], S13, 0xffff5bb1); // 11
    FF(b, c, d, a, x[11], S14, 0x895cd7be); // 12
    FF(a, b, c, d, x[12], S11, 0x6b901122); // 13
    FF(d, a, b, c, x[13], S12, 0xfd987193); // 14
    FF(c, d, a, b, x[14], S13, 0xa679438e); // 15
    FF(b, c, d, a, x[15], S14, 0x49b40821); // 16
    // Round 2
    GG(a, b, c, d, x[1], S21, 0xf61e2562); // 17
    GG(d, a, b, c, x[6], S22, 0xc040b340); // 18
    GG(c, d, a, b, x[11], S23, 0x265e5a51); // 19
    GG(b, c, d, a, x[0], S24, 0xe9b6c7aa); // 20
    GG(a, b, c, d, x[5], S21, 0xd62f105d); // 21
    GG(d, a, b, c, x[10], S22, 0x2441453); // 22
    GG(c, d, a, b, x[15], S23, 0xd8a1e681); // 23
    GG(b, c, d, a, x[4], S24, 0xe7d3fbc8); // 24
    GG(a, b, c, d, x[9], S21, 0x21e1cde6); // 25
    GG(d, a, b, c, x[14], S22, 0xc33707d6); // 26
    GG(c, d, a, b, x[3], S23, 0xf4d50d87); // 27
    GG(b, c, d, a, x[8], S24, 0x455a14ed); // 28
    GG(a, b, c, d, x[13], S21, 0xa9e3e905); // 29
    GG(d, a, b, c, x[2], S22, 0xfcefa3f8); // 30
    GG(c, d, a, b, x[7], S23, 0x676f02d9); // 31
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); // 32
    // Round 3
    HH(a, b, c, d, x[5], S31, 0xfffa3942); // 33
    HH(d, a, b, c, x[8], S32, 0x8771f681); // 34
    HH(c, d, a, b, x[11], S33, 0x6d9d6122); // 35
    HH(b, c, d, a, x[14], S34, 0xfde5380c); // 36
    HH(a, b, c, d, x[1], S31, 0xa4beea44); // 37
    HH(d, a, b, c, x[4], S32, 0x4bdecfa9); // 38
    HH(c, d, a, b, x[7], S33, 0xf6bb4b60); // 39
    HH(b, c, d, a, x[10], S34, 0xbebfbc70); // 40
    HH(a, b, c, d, x[13], S31, 0x289b7ec6); // 41
    HH(d, a, b, c, x[0], S32, 0xeaa127fa); // 42
    HH(c, d, a, b, x[3], S33, 0xd4ef3085); // 43
    HH(b, c, d, a, x[6], S34, 0x4881d05); // 44
    HH(a, b, c, d, x[9], S31, 0xd9d4d039); // 45
    HH(d, a, b, c, x[12], S32, 0xe6db99e5); // 46
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8); // 47
    HH(b, c, d, a, x[2], S34, 0xc4ac5665); // 48
    // Round 4
    II(a, b, c, d, x[0], S41, 0xf4292244); // 49
    II(d, a, b, c, x[7], S42, 0x432aff97); // 50
    II(c, d, a, b, x[14], S43, 0xab9423a7); // 51
    II(b, c, d, a, x[5], S44, 0xfc93a039); // 52
    II(a, b, c, d, x[12], S41, 0x655b59c3); // 53
    II(d, a, b, c, x[3], S42, 0x8f0ccc92); // 54
    II(c, d, a, b, x[10], S43, 0xffeff47d); // 55
    II(b, c, d, a, x[1], S44, 0x85845dd1); // 56
    II(a, b, c, d, x[8], S41, 0x6fa87e4f); // 57
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0); // 58
    II(c, d, a, b, x[6], S43, 0xa3014314); // 59
    II(b, c, d, a, x[13], S44, 0x4e0811a1); // 60
    II(a, b, c, d, x[4], S41, 0xf7537e82); // 61
    II(d, a, b, c, x[11], S42, 0xbd3af235); // 62
    II(c, d, a, b, x[2], S43, 0x2ad7d2bb); // 63
    II(b, c, d, a, x[9], S44, 0xeb86d391); // 64
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;

    // Reset sensitive information.
    memset(x, 0, sizeof(x));
}


//
// MD5 block update operation. Continues an MD5 message-digest
// operation, processing another message block, and updating the
// context.
//

static void
md5_addn(fingerprint_ty *p, unsigned char *input, size_t inputLen)
{
    md5_ty	    *context;
    size_t          i;
    size_t          idx;
    size_t          partLen;

    context = (md5_ty *)p;
    // Compute number of bytes mod 64
    idx = (context->count[0] >> 3) & 0x3F;
    // Update number of bits
    context->count[0] += (inputLen << 3);
    if (context->count[0] < (inputLen << 3))
	context->count[1]++;
    context->count[1] += (inputLen >> 29);
    partLen = 64 - idx;

    //
    // Transform as many times as possible.
    //
    if (inputLen >= partLen)
    {
	memcpy(&context->buffer[idx], input, partLen);
	MD5Transform(context->state, context->buffer);
	for (i = partLen; i + 63 < inputLen; i += 64)
    	    MD5Transform(context->state, &input[i]);
	idx = 0;
    }
    else
	i = 0;
    // Buffer remaining input
    memcpy(&context->buffer[idx], &input[i], inputLen - i);
}


//
// MD5 finalization.
// Ends an MD5 message-digest operation, writing the message digest
// and resetting the context.
//

static int
md5_hash(fingerprint_ty *p, unsigned char *digest)
{
    md5_ty	    *context;
    unsigned char   bits[8];
    unsigned int    idx;
    unsigned int    padLen;

    //
    // Save number of bits
    //
    context = (md5_ty *)p;
    Encode(bits, context->count, 8);

    //
    // Pad out to 56 mod 64.
    //
    idx = (unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen = (idx < 56) ? (56 - idx) : (120 - idx);
    md5_addn(p, PADDING, padLen);

    //
    // Append length (before padding)
    //
    md5_addn(p, bits, 8);

    //
    // Store state in digest
    //
    Encode(digest, context->state, 16);

    //
    // reset sensitive information.
    //
    reset(context);

    //
    // return length of hash
    //
    return MD5_HASH_LEN;
}


static void
md5_sum(fingerprint_ty *p, char *obuf, size_t obuf_len)
{
    unsigned char   h[MD5_HASH_LEN];
    char	    *cp;
    int		    i;

    md5_hash(p, h);
    cp = obuf;
    for (i = 0; i < MD5_HASH_LEN; ++i)
    {
	snprintf(cp, obuf + obuf_len - cp, "%2.2X", h[i]);
	cp += strlen(cp);
    }
    *cp = 0;
}


fingerprint_methods_ty fp_md5 =
{
    sizeof(md5_ty),
    "md5",
    md5_constructor,
    md5_destructor,
    md5_addn,
    md5_hash,
    md5_sum
};
