/*
 **********************************************************************
 ** Copyright (C) 1990, RSA Data Security, Inc. 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.                                   **
 **********************************************************************
 */

// includes
#include "PdfEncrypt.h"

namespace PoDoFo {

// ----------------
// MD5 by RSA
// ----------------

// C headers for MD5
#include <sys/types.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MD5_HASHBYTES 16

/// Structure representing an MD5 context while ecrypting. (For internal use only)
typedef struct MD5Context
{
  unsigned int buf[4];
  unsigned int bits[2];
  unsigned char in[64];
} MD5_CTX;

static void  MD5Init(MD5_CTX *context);
static void  MD5Update(MD5_CTX *context, unsigned char const *buf, unsigned len);
static void  MD5Final(unsigned char digest[MD5_HASHBYTES], MD5_CTX *context);
static void  MD5Transform(unsigned int buf[4], unsigned int const in[16]);
static char* MD5End(MD5_CTX *, char *);

static char* MD5End(MD5_CTX *ctx, char *buf)
{
  int i;
  unsigned char digest[MD5_HASHBYTES];
  char hex[]="0123456789abcdef";

  if (!buf)
  {
    buf = static_cast<char*>(malloc(33));
  }
    
  if (!buf)
  {
    return 0;
  }
    
  MD5Final(digest,ctx);
  for (i=0;i<MD5_HASHBYTES;i++)
  {
    buf[i+i] = hex[digest[i] >> 4];
    buf[i+i+1] = hex[digest[i] & 0x0f];
  }
  buf[i+i] = '\0';
  return buf;
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
static void MD5Final(unsigned char digest[MD5_HASHBYTES], MD5_CTX *ctx)
{
  unsigned count;
  unsigned char *p;

  /* Compute number of bytes mod 64 */
  count = (ctx->bits[0] >> 3) & 0x3F; 

  /* Set the first char of padding to 0x80.  This is safe since there is
     always at least one byte free */
  p = ctx->in + count;
  *p++ = 0x80;

  /* Bytes of padding needed to make 64 bytes */
  count = 64 - 1 - count;

  /* Pad out to 56 mod 64 */
  if (count < 8)
  {
    /* Two lots of padding:  Pad the first block to 64 bytes */
    memset(p, 0, count);
    MD5Transform(ctx->buf, reinterpret_cast<unsigned int *>(ctx->in));

    /* Now fill the next block with 56 bytes */
    memset(ctx->in, 0, 56);
  }
  else
  {
    /* Pad block to 56 bytes */
    memset(p, 0, count - 8);   
  }

  /* Append length in bits and transform */
  reinterpret_cast<unsigned int *>(ctx->in)[14] = ctx->bits[0];
  reinterpret_cast<unsigned int *>(ctx->in)[15] = ctx->bits[1];

  MD5Transform(ctx->buf, reinterpret_cast<unsigned int *>(ctx->in));
  memcpy(digest, ctx->buf, MD5_HASHBYTES);
  memset((char *) ctx, 0, sizeof(ctx));       /* In case it's sensitive */
}

static void MD5Init(MD5_CTX *ctx)
{
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

static void MD5Update(MD5_CTX *ctx, unsigned char const *buf, unsigned len)
{
  unsigned int t;

  /* Update bitcount */

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ( static_cast<unsigned int>(len) << 3)) < t)
  {
        ctx->bits[1]++;         /* Carry from low to high */
  }
  ctx->bits[1] += len >> 29;

  t = (t >> 3) & 0x3f;        /* Bytes already in shsInfo->data */

  /* Handle any leading odd-sized chunks */

  if (t)
  {
    unsigned char *p = static_cast<unsigned char *>(ctx->in) + t;

    t = 64 - t;
    if (len < t)
    {
      memcpy(p, buf, len);
      return;
    }
    memcpy(p, buf, t);
    MD5Transform(ctx->buf, reinterpret_cast<unsigned int *>(ctx->in));
    buf += t;
    len -= t;
  }
  /* Process data in 64-byte chunks */

  while (len >= 64)
  {
    memcpy(ctx->in, buf, 64);
    MD5Transform(ctx->buf, reinterpret_cast<unsigned int *>(ctx->in));
    buf += 64;
    len -= 64;
  }

  /* Handle any remaining bytes of data. */

  memcpy(ctx->in, buf, len);
}


/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))   
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
        ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void MD5Transform(unsigned int buf[4], unsigned int const in[16])
{
  register unsigned int a, b, c, d;

  a = buf[0];
  b = buf[1];
  c = buf[2];
  d = buf[3];

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7); 
  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7); 
  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22); 
  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);  
  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12); 
  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7); 
  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);  
  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);  
  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20); 
  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);  
  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9); 
  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20); 
  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);  
  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9); 
  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14); 
  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20); 
  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);  
  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);  
  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11); 
  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16); 
  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4); 
  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11); 
  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16); 
  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23); 
  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);  
  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23); 

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21); 
  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6); 
  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10); 
  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21); 
  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);  
  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15); 
  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);  
  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15); 
  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21); 

  buf[0] += a;
  buf[1] += b;
  buf[2] += c;
  buf[3] += d;
}
 

#ifndef REVERSEBYTE
#define byteReverse(buf, len)   /* Nothing */
#else
void byteReverse(unsigned char *buf, unsigned longs);

/*
 * Note: this code is harmless on little-endian machines.
 */
static void byteReverse(unsigned char *buf, unsigned longs)
{
  unsigned int t;
  do
  {
    t = (unsigned int) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
        ((unsigned) buf[1] << 8 | buf[0]);
    *(unsigned int *) buf = t;  
    buf += 4;
  }
  while (--longs);
}
#endif


/***************************************************************************
*   Copyright (C) 2006 by Dominik Seichter                                *
*   domseichter@web.de                                                    *
*                                                                         *
*   This program is free software; you can redistribute it and/or modify  *
*   it under the terms of the GNU Library General Public License as       *
*   published by the Free Software Foundation; either version 2 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 Library General Public     *
*   License along with this program; if not, write to the                 *
*   Free Software Foundation, Inc.,                                       *
*   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
***************************************************************************/

// ---------------------------
// PdfEncrypt implementation
// Based on code from Ulrich Telle: http://wxcode.sourceforge.net/components/wxpdfdoc/
// ---------------------------


static unsigned char padding[] =
  "\x28\xBF\x4E\x5E\x4E\x75\x8A\x41\x64\x00\x4E\x56\xFF\xFA\x01\x08\x2E\x2E\x00\xB6\xD0\x68\x3E\x80\x2F\x0C\xA9\xFE\x64\x53\x69\x7A";

PdfEncrypt::PdfEncrypt()
{
  int j;
  for (j = 0; j < 5; j++)
  {
    m_rc4key[j] = 0;
  }
}

PdfEncrypt::~PdfEncrypt()
{
}

void
PdfEncrypt::PadPassword(const std::string& password, unsigned char pswd[32])
{
  int m = password.length();
  if (m > 32) m = 32;

  int j;
  int p = 0;
  for (j = 0; j < m; j++)
  {
    pswd[p++] = (unsigned char) password[j];
  }
  for (j = 0; p < 32 && j < 32; j++)
  {
    pswd[p++] = padding[j];
  }
}

void
PdfEncrypt::GenerateEncryptionKey(const std::string& userPassword,
                                    const std::string& ownerPassword,
									PdfKeyLength inKeyLength,
                                    int protection)
{
  int j;
  unsigned char userpswd[32];
  unsigned char ownerpswd[32];
  unsigned char digest[MD5_HASHBYTES];

  // Pad passwords
  PadPassword(userPassword, userpswd);
  PadPassword(ownerPassword, ownerpswd);

  // Compute O value
  GetMD5Binary(ownerpswd, 32, digest);
  RC4(digest, 5, userpswd, 32, m_Ovalue);

  // Compute encryption key
  const int buflen = 32 + 32 + 4;
  unsigned char buffer[buflen];
  for (j = 0; j < 32; j++)
  {
    buffer[j]    = userpswd[j];
    buffer[j+32] = m_Ovalue[j];
  }
  buffer[64+0] = protection & 0xff;
  buffer[64+1] = 0xff;
  buffer[64+2] = 0xff;
  buffer[64+3] = 0xff;
  GetMD5Binary(buffer, buflen, digest);
  for (j = 0; j < 5; j++)
  {
    m_encryptionKey[j] = digest[j];
  }

  // Compute U value
  RC4(m_encryptionKey, 5, padding, 32, m_Uvalue);

  // Compute P value
  m_Pvalue = -((protection ^ 255) + 1);
}

void
PdfEncrypt::Encrypt(int n, unsigned char* str, int len)
{
  unsigned char objkey[MD5_HASHBYTES];
  unsigned char nkey[10];
  int j;
  for (j = 0; j < 5; j++)
  {
    nkey[j] = m_encryptionKey[j];
  }
  nkey[5] = 0xff &  n;
  nkey[6] = 0xff & (n >> 8);
  nkey[7] = 0xff & (n >> 16);
  nkey[8] = 0;
  nkey[9] = 0;
  GetMD5Binary(nkey, 10, objkey);
  RC4(objkey, 10, str, len, str);
}

/**
* RC4 is the standard encryption algorithm used in PDF format
*/

void
PdfEncrypt::RC4(unsigned char* key, int keylen,
                  unsigned char* textin, int textlen,
                  unsigned char* textout)
{
  int i;
  int j;
  int t;
  unsigned char rc4[256];

  if (memcmp(key,m_rc4key,keylen) != 0)
  {
    for (i = 0; i < 256; i++)
    {
      rc4[i] = i;
    }
    j = 0;
    for (i = 0; i < 256; i++)
    {
      t = rc4[i];
      j = (j + t + key[i % keylen]) % 256;
      rc4[i] = rc4[j];
      rc4[j] = t;
    }
    memcpy(m_rc4key,key,keylen);
    memcpy(m_rc4last,rc4,256);
  }
  else
  {
    memcpy(rc4,m_rc4last,256);
  }

  int a = 0;
  int b = 0;
  unsigned char k;
  for (i = 0; i < textlen; i++)
  {
    a = (a + 1) % 256;
    t = rc4[a];
    b = (b + t) % 256;
    rc4[a] = rc4[b];
    rc4[b] = t;
    k = rc4[(rc4[a] + rc4[b]) % 256];
    textout[i] = textin[i] ^ k;
  }
}

PdfString PdfEncrypt::GetMD5String( const unsigned char* pBuffer, int nLength )
{
    char data[MD5_HASHBYTES];

    PdfEncrypt::GetMD5Binary( pBuffer, nLength, (unsigned char*)data );

    return PdfString( data, MD5_HASHBYTES, true );
}

void PdfEncrypt::GetMD5Binary(const unsigned char* data, int length, unsigned char* digest)
{
  MD5_CTX ctx;
  MD5Init(&ctx);
  MD5Update(&ctx, data, length);
  MD5Final(digest,&ctx);
}

};


