/* md5c.c: "RSA Data Security, Inc. MD5 Message-Digest Algorithm"
   "derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm"

%%% portions-copyright-cmetz-96
Portions of this software are Copyright 1996-1999 by Craig Metz, All Rights
Reserved. The Inner Net License Version 2 applies to these portions of
the software.
You should have received a copy of the license with this software. If
you didn't get a copy, you may request one from <license@inner.net>.

Portions of this software are Copyright 1995 by Randall Atkinson and Dan
McDonald, All Rights Reserved. All Rights under this copyright are assigned
to the U.S. Naval Research Laboratory (NRL). The NRL Copyright Notice and
License Agreement applies to this software.

        History:

	Modified by cmetz for OPIE 2.3. Changed PTR to VOIDPTR.
	Modified by cmetz for OPIE 2.2. Use FUNCTION declaration et al.
             Don't play macro games with memset/memcpy. Renamed exported
             functions to avoid conflicts. Use unified context structure.
	Modified at NRL for OPIE 2.1. Minor autoconf mods.
	Modified at NRL for OPIE 2.0.
        Originally from RSADSI reference code.
*/
/* 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 "opie_cfg.h"
#include "opie.h"

/* 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 VOIDRET MD5Transform __P((UINT4[4], unsigned char[64]));

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
};

/*
 * Encodes input (UINT4) into output (unsigned char).
 * Assumes len is a multiple of 4.
 */
static VOIDRET EEncode FUNCTION((output, input, len), unsigned char *output AND UINT4 *input AND unsigned int len)
{
  unsigned int i, j;

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

/*
 * Decodes input (unsigned char) into output (UINT4).
 * Assumes len is a multiple of 4.
 */
static VOIDRET EDecode FUNCTION((output, input, len), UINT4 *output AND unsigned char *input AND unsigned int len)
{
  unsigned int i, j;

  for (i = 0, j = 0; j < len; i++, j += 4)
    output[i] = ((UINT4) input[j]) | (((UINT4) input[j + 1]) << 8) |
      (((UINT4) input[j + 2]) << 16) | (((UINT4) input[j + 3]) << 24);
}

/* 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) (((x) << (n)) | ((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) { \
 (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

#define GG(a, b, c, d, x, s, ac) { \
 (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

#define HH(a, b, c, d, x, s, ac) { \
 (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

#define II(a, b, c, d, x, s, ac) { \
 (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

/* MD5 initialization. Begins an MD5 operation, writing a new context.  */
VOIDRET opiemd5init FUNCTION((context), struct opiemdx_ctx *context)
{
  context->count[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;
}

/*
 * MD5 block update operation. Continues an MD5 message-digest
 * operation, processing another message block, and updating the
 * context.
 */
VOIDRET opiemd5update FUNCTION((context, input, inputLen), struct opiemdx_ctx *context AND unsigned char *input AND unsigned int inputLen)
{
  unsigned int i, index, partLen;

  /* Compute number of bytes mod 64 */
  index = (unsigned int) ((context->count[0] >> 3) & 0x3F);

  /* Update number of bits */
  if ((context->count[0] += ((UINT4) inputLen << 3)) < ((UINT4) inputLen << 3))
    context->count[1]++;

  context->count[1] += ((UINT4) inputLen >> 29);
  partLen = 64 - index;

  /* Transform as many times as possible. */
  if (inputLen >= partLen) {
    memcpy((VOIDPTR)&context->buffer[index], (VOIDPTR)input, partLen);
    MD5Transform(context->state, context->buffer);

    for (i = partLen; i + 63 < inputLen; i += 64)
      MD5Transform(context->state, &input[i]);

    index = 0;
  } else
    i = 0;

  /* Buffer remaining input */
  memcpy((VOIDPTR) & context->buffer[index],
	     (VOIDPTR) & input[i],
	     inputLen - i);
}

/* MD5 finalization. Ends an MD5 message-digest operation, writing the
   the message digest and zeroizing the context.
 */
VOIDRET opiemd5final FUNCTION((digest, context), unsigned char *digest AND struct opiemdx_ctx *context)
{
  unsigned char bits[8];
  unsigned int index, padLen;

  /* Save number of bits */
  EEncode(bits, context->count, 8);

  /* Pad out to 56 mod 64. */
  index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
  padLen = (index < 56) ? (56 - index) : (120 - index);
  opiemd5update(context, PADDING, padLen);

  /* Append length (before padding) */
  opiemd5update(context, bits, 8);

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

  /* Zeroize sensitive information. */
  memset((VOIDPTR) context, 0, sizeof(*context));
}

/* MD5 basic transformation. Transforms state based on block.  */
static VOIDRET MD5Transform FUNCTION((state, block), UINT4 state[4] AND unsigned char block[64])
{
  UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

  EDecode(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;

  /* Zeroize sensitive information. */
  memset((VOIDPTR)x, 0, sizeof(x));
}