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//========================================================================
//
// Decrypt.cc
//
// Copyright 1996-2003 Glyph & Cog, LLC
//
//========================================================================

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//========================================================================
//
// Modified under the Poppler project - http://poppler.freedesktop.org
//
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// All changes made under the Poppler project to this file are licensed
// under GPL version 2 or later
//
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// Copyright (C) 2008 Julien Rebetez <julien@fhtagn.net>
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// Copyright (C) 2008, 2010, 2016-2018 Albert Astals Cid <aacid@kde.org>
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// Copyright (C) 2009 Matthias Franz <matthias@ktug.or.kr>
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// Copyright (C) 2009 David Benjamin <davidben@mit.edu>
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// Copyright (C) 2012 Fabio D'Urso <fabiodurso@hotmail.it>
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// Copyright (C) 2013, 2017 Adrian Johnson <ajohnson@redneon.com>
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// Copyright (C) 2016 Alok Anand <alok4nand@gmail.com>
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// Copyright (C) 2016 Thomas Freitag <Thomas.Freitag@alfa.de>
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//
// To see a description of the changes please see the Changelog file that
// came with your tarball or type make ChangeLog if you are building from git
//
//========================================================================

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#include <config.h>

#ifdef USE_GCC_PRAGMAS
#pragma implementation
#endif

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#include <cstdint>
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#include <string.h>
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#include "goo/gmem.h"
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#include "goo/grandom.h"
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#include "Decrypt.h"
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#include "Error.h"
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static void rc4InitKey(Guchar *key, int keyLen, Guchar *state);
static Guchar rc4DecryptByte(Guchar *state, Guchar *x, Guchar *y, Guchar c);

static GBool aesReadBlock(Stream  *str, Guchar *in, GBool addPadding);

static void aesKeyExpansion(DecryptAESState *s, Guchar *objKey, int objKeyLen, GBool decrypt);
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static void aesEncryptBlock(DecryptAESState *s, Guchar *in);
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static void aesDecryptBlock(DecryptAESState *s, Guchar *in, GBool last);
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static void aes256KeyExpansion(DecryptAES256State *s, Guchar *objKey, int objKeyLen, GBool decrypt);
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static void aes256EncryptBlock(DecryptAES256State *s, Guchar *in);
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static void aes256DecryptBlock(DecryptAES256State *s, Guchar *in, GBool last);
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static void sha256(Guchar *msg, int msgLen, Guchar *hash);
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static void sha384(Guchar *msg, int msgLen, Guchar *hash);
static void sha512(Guchar *msg, int msgLen, Guchar *hash);

static void revision6Hash(GooString *inputPassword, Guchar *K, char *userKey);
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static const Guchar passwordPad[32] = {
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  0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41,
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  0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08,
  0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80,
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  0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a
};

//------------------------------------------------------------------------
// Decrypt
//------------------------------------------------------------------------

GBool Decrypt::makeFileKey(int encVersion, int encRevision, int keyLength,
			   GooString *ownerKey, GooString *userKey,
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			   GooString *ownerEnc, GooString *userEnc,
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			   int permissions, GooString *fileID,
			   GooString *ownerPassword, GooString *userPassword,
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			   Guchar *fileKey, GBool encryptMetadata,
			   GBool *ownerPasswordOk) {
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  DecryptAES256State state;
  Guchar test[127 + 56], test2[32];
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  GooString *userPassword2;
  Guchar fState[256];
  Guchar tmpKey[16];
  Guchar fx, fy;
  int len, i, j;

  *ownerPasswordOk = gFalse;
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  if (encRevision == 5 || encRevision == 6) {
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    // check the owner password
    if (ownerPassword) {
      //~ this is supposed to convert the password to UTF-8 using "SASLprep"
      len = ownerPassword->getLength();
      if (len > 127) {
	len = 127;
      }
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      memcpy(test, ownerPassword->getCString(), len);
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      memcpy(test + len, ownerKey->getCString() + 32, 8);
      memcpy(test + len + 8, userKey->getCString(), 48);
      sha256(test, len + 56, test);
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      if (encRevision == 6) {
	//test contains the initial SHA-256 hash as input K.
	revision6Hash(ownerPassword, test, userKey->getCString());
      }
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      if (!memcmp(test, ownerKey->getCString(), 32)) {

	// compute the file key from the owner password
	memcpy(test, ownerPassword->getCString(), len);
	memcpy(test + len, ownerKey->getCString() + 40, 8);
	memcpy(test + len + 8, userKey->getCString(), 48);
	sha256(test, len + 56, test);
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	if (encRevision == 6) {
	  //test contains the initial SHA-256 hash input K.
	  revision6Hash(ownerPassword, test, userKey->getCString());
	}
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	aes256KeyExpansion(&state, test, 32, gTrue);
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	for (i = 0; i < 16; ++i) {
	  state.cbc[i] = 0;
	}
	aes256DecryptBlock(&state, (Guchar *)ownerEnc->getCString(), gFalse);
	memcpy(fileKey, state.buf, 16);
	aes256DecryptBlock(&state, (Guchar *)ownerEnc->getCString() + 16,
			   gFalse);
	memcpy(fileKey + 16, state.buf, 16);

	*ownerPasswordOk = gTrue;
	return gTrue;
      }
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    }
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    // check the user password
    if (userPassword) {
      //~ this is supposed to convert the password to UTF-8 using "SASLprep"
      len = userPassword->getLength();
      if (len > 127) {
	len = 127;
      }
      memcpy(test, userPassword->getCString(), len);
      memcpy(test + len, userKey->getCString() + 32, 8);
      sha256(test, len + 8, test);
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      if(encRevision == 6) {
	// test contains the initial SHA-256 hash input K.
	// user key is not used in checking user password.
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	revision6Hash(userPassword, test, nullptr);
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      }
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      if (!memcmp(test, userKey->getCString(), 32)) {

	// compute the file key from the user password
	memcpy(test, userPassword->getCString(), len);
	memcpy(test + len, userKey->getCString() + 40, 8);
	sha256(test, len + 8, test);
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	if(encRevision == 6) {
	  //test contains the initial SHA-256 hash input K.
	  //user key is not used in computing intermediate user key.
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	  revision6Hash(userPassword, test, nullptr);
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	}
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	aes256KeyExpansion(&state, test, 32, gTrue);
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	for (i = 0; i < 16; ++i) {
	  state.cbc[i] = 0;
	}
	aes256DecryptBlock(&state, (Guchar *)userEnc->getCString(), gFalse);
	memcpy(fileKey, state.buf, 16);
	aes256DecryptBlock(&state, (Guchar *)userEnc->getCString() + 16,
			   gFalse);
	memcpy(fileKey + 16, state.buf, 16);

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	return gTrue;
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      }
    }
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    return gFalse;
  } else {

    // try using the supplied owner password to generate the user password
    if (ownerPassword) {
      len = ownerPassword->getLength();
      if (len < 32) {
	memcpy(test, ownerPassword->getCString(), len);
	memcpy(test + len, passwordPad, 32 - len);
      } else {
	memcpy(test, ownerPassword->getCString(), 32);
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      }
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      md5(test, 32, test);
      if (encRevision == 3) {
	for (i = 0; i < 50; ++i) {
	  md5(test, keyLength, test);
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	}
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      }
      if (encRevision == 2) {
	rc4InitKey(test, keyLength, fState);
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	fx = fy = 0;
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	for (i = 0; i < 32; ++i) {
	  test2[i] = rc4DecryptByte(fState, &fx, &fy, ownerKey->getChar(i));
	}
      } else {
	memcpy(test2, ownerKey->getCString(), 32);
	for (i = 19; i >= 0; --i) {
	  for (j = 0; j < keyLength; ++j) {
	    tmpKey[j] = test[j] ^ i;
	  }
	  rc4InitKey(tmpKey, keyLength, fState);
	  fx = fy = 0;
	  for (j = 0; j < 32; ++j) {
	    test2[j] = rc4DecryptByte(fState, &fx, &fy, test2[j]);
	  }
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	}
      }
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      userPassword2 = new GooString((char *)test2, 32);
      if (makeFileKey2(encVersion, encRevision, keyLength, ownerKey, userKey,
		       permissions, fileID, userPassword2, fileKey,
		       encryptMetadata)) {
	*ownerPasswordOk = gTrue;
	delete userPassword2;
	return gTrue;
      }
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      delete userPassword2;
    }

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    // try using the supplied user password
    return makeFileKey2(encVersion, encRevision, keyLength, ownerKey, userKey,
			permissions, fileID, userPassword, fileKey,
			encryptMetadata);
  }
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}

GBool Decrypt::makeFileKey2(int encVersion, int encRevision, int keyLength,
			    GooString *ownerKey, GooString *userKey,
			    int permissions, GooString *fileID,
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			    GooString *userPassword, Guchar *fileKey,
			    GBool encryptMetadata) {
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  Guchar *buf;
  Guchar test[32];
  Guchar fState[256];
  Guchar tmpKey[16];
  Guchar fx, fy;
  int len, i, j;
  GBool ok;

  // generate file key
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  buf = (Guchar *)gmalloc(72 + fileID->getLength());
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  if (userPassword) {
    len = userPassword->getLength();
    if (len < 32) {
      memcpy(buf, userPassword->getCString(), len);
      memcpy(buf + len, passwordPad, 32 - len);
    } else {
      memcpy(buf, userPassword->getCString(), 32);
    }
  } else {
    memcpy(buf, passwordPad, 32);
  }
  memcpy(buf + 32, ownerKey->getCString(), 32);
  buf[64] = permissions & 0xff;
  buf[65] = (permissions >> 8) & 0xff;
  buf[66] = (permissions >> 16) & 0xff;
  buf[67] = (permissions >> 24) & 0xff;
  memcpy(buf + 68, fileID->getCString(), fileID->getLength());
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  len = 68 + fileID->getLength();
  if (!encryptMetadata) {
    buf[len++] = 0xff;
    buf[len++] = 0xff;
    buf[len++] = 0xff;
    buf[len++] = 0xff;
  }
  md5(buf, len, fileKey);
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  if (encRevision == 3) {
    for (i = 0; i < 50; ++i) {
      md5(fileKey, keyLength, fileKey);
    }
  }

  // test user password
  if (encRevision == 2) {
    rc4InitKey(fileKey, keyLength, fState);
    fx = fy = 0;
    for (i = 0; i < 32; ++i) {
      test[i] = rc4DecryptByte(fState, &fx, &fy, userKey->getChar(i));
    }
    ok = memcmp(test, passwordPad, 32) == 0;
  } else if (encRevision == 3) {
    memcpy(test, userKey->getCString(), 32);
    for (i = 19; i >= 0; --i) {
      for (j = 0; j < keyLength; ++j) {
	tmpKey[j] = fileKey[j] ^ i;
      }
      rc4InitKey(tmpKey, keyLength, fState);
      fx = fy = 0;
      for (j = 0; j < 32; ++j) {
	test[j] = rc4DecryptByte(fState, &fx, &fy, test[j]);
      }
    }
    memcpy(buf, passwordPad, 32);
    memcpy(buf + 32, fileID->getCString(), fileID->getLength());
    md5(buf, 32 + fileID->getLength(), buf);
    ok = memcmp(test, buf, 16) == 0;
  } else {
    ok = gFalse;
  }

  gfree(buf);
  return ok;
}

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//------------------------------------------------------------------------
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// BaseCryptStream
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//------------------------------------------------------------------------

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BaseCryptStream::BaseCryptStream(Stream *strA, Guchar *fileKey, CryptAlgorithm algoA,
				 int keyLength, int objNum, int objGen):
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  FilterStream(strA)
{
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  int i;
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  algo = algoA;

  // construct object key
  for (i = 0; i < keyLength; ++i) {
    objKey[i] = fileKey[i];
  }
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  switch (algo) {
  case cryptRC4:
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    if (likely(keyLength < static_cast<int>(sizeof(objKey) - 4))) {
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      objKey[keyLength] = objNum & 0xff;
      objKey[keyLength + 1] = (objNum >> 8) & 0xff;
      objKey[keyLength + 2] = (objNum >> 16) & 0xff;
      objKey[keyLength + 3] = objGen & 0xff;
      objKey[keyLength + 4] = (objGen >> 8) & 0xff;
      md5(objKey, keyLength + 5, objKey);
    }
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    if ((objKeyLength = keyLength + 5) > 16) {
      objKeyLength = 16;
    }
    break;
  case cryptAES:
    objKey[keyLength] = objNum & 0xff;
    objKey[keyLength + 1] = (objNum >> 8) & 0xff;
    objKey[keyLength + 2] = (objNum >> 16) & 0xff;
    objKey[keyLength + 3] = objGen & 0xff;
    objKey[keyLength + 4] = (objGen >> 8) & 0xff;
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    objKey[keyLength + 5] = 0x73; // 's'
    objKey[keyLength + 6] = 0x41; // 'A'
    objKey[keyLength + 7] = 0x6c; // 'l'
    objKey[keyLength + 8] = 0x54; // 'T'
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    md5(objKey, keyLength + 9, objKey);
    if ((objKeyLength = keyLength + 5) > 16) {
      objKeyLength = 16;
    }
    break;
  case cryptAES256:
    objKeyLength = keyLength;
    break;
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  case cryptNone:
    break;
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  }
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  charactersRead = 0;
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  autoDelete = gTrue;
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}

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BaseCryptStream::~BaseCryptStream() {
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  if (autoDelete) {
    delete str;
  }
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}

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void BaseCryptStream::reset() {
  charactersRead = 0;
  nextCharBuff = EOF;
  str->reset();
}

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Goffset BaseCryptStream::getPos() {
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  return charactersRead;
}

int BaseCryptStream::getChar() {
  // Read next character and empty the buffer, so that a new character will be read next time
  int c = lookChar();
  nextCharBuff = EOF;

  if (c != EOF)
    charactersRead++;
  return c;
}

GBool BaseCryptStream::isBinary(GBool last) {
  return str->isBinary(last);
}

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void BaseCryptStream::setAutoDelete(GBool val) {
  autoDelete = val;
}

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//------------------------------------------------------------------------
// EncryptStream
//------------------------------------------------------------------------

EncryptStream::EncryptStream(Stream *strA, Guchar *fileKey, CryptAlgorithm algoA,
			     int keyLength, int objNum, int objGen):
  BaseCryptStream(strA, fileKey, algoA, keyLength, objNum, objGen)
{
  // Fill the CBC initialization vector for AES and AES-256
  switch (algo) {
  case cryptAES:
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    grandom_fill(state.aes.cbc, 16);
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    break;
  case cryptAES256:
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    grandom_fill(state.aes256.cbc, 16);
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    break;
  default:
    break;
  }
}

EncryptStream::~EncryptStream() {
}

void EncryptStream::reset() {
  BaseCryptStream::reset();

  switch (algo) {
  case cryptRC4:
    state.rc4.x = state.rc4.y = 0;
    rc4InitKey(objKey, objKeyLength, state.rc4.state);
    break;
  case cryptAES:
    aesKeyExpansion(&state.aes, objKey, objKeyLength, gFalse);
    memcpy(state.aes.buf, state.aes.cbc, 16); // Copy CBC IV to buf
    state.aes.bufIdx = 0;
    state.aes.paddingReached = gFalse;
    break;
  case cryptAES256:
    aes256KeyExpansion(&state.aes256, objKey, objKeyLength, gFalse);
    memcpy(state.aes256.buf, state.aes256.cbc, 16); // Copy CBC IV to buf
    state.aes256.bufIdx = 0;
    state.aes256.paddingReached = gFalse;
    break;
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  case cryptNone:
    break;
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  }
}

int EncryptStream::lookChar() {
  Guchar in[16];
  int c;

  if (nextCharBuff != EOF)
    return nextCharBuff;

  c = EOF; // make gcc happy
  switch (algo) {
  case cryptRC4:
    if ((c = str->getChar()) != EOF) {
      // RC4 is XOR-based: the decryption algorithm works for encryption too
      c = rc4DecryptByte(state.rc4.state, &state.rc4.x, &state.rc4.y, (Guchar)c);
    }
    break;
  case cryptAES:
    if (state.aes.bufIdx == 16 && !state.aes.paddingReached) {
      state.aes.paddingReached = !aesReadBlock(str, in, gTrue);
      aesEncryptBlock(&state.aes, in);
    }
    if (state.aes.bufIdx == 16) {
      c = EOF;
    } else {
      c = state.aes.buf[state.aes.bufIdx++];
    }
    break;
  case cryptAES256:
    if (state.aes256.bufIdx == 16 && !state.aes256.paddingReached) {
      state.aes256.paddingReached = !aesReadBlock(str, in, gTrue);
      aes256EncryptBlock(&state.aes256, in);
    }
    if (state.aes256.bufIdx == 16) {
      c = EOF;
    } else {
      c = state.aes256.buf[state.aes256.bufIdx++];
    }
    break;
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  case cryptNone:
    break;
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  }
  return (nextCharBuff = c);
}

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//------------------------------------------------------------------------
// DecryptStream
//------------------------------------------------------------------------

DecryptStream::DecryptStream(Stream *strA, Guchar *fileKey, CryptAlgorithm algoA,
			     int keyLength, int objNum, int objGen):
  BaseCryptStream(strA, fileKey, algoA, keyLength, objNum, objGen)
{
}

DecryptStream::~DecryptStream() {
}

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void DecryptStream::reset() {
  int i;
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  BaseCryptStream::reset();
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  switch (algo) {
  case cryptRC4:
    state.rc4.x = state.rc4.y = 0;
    rc4InitKey(objKey, objKeyLength, state.rc4.state);
    break;
  case cryptAES:
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    aesKeyExpansion(&state.aes, objKey, objKeyLength, gTrue);
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    for (i = 0; i < 16; ++i) {
      state.aes.cbc[i] = str->getChar();
    }
    state.aes.bufIdx = 16;
    break;
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  case cryptAES256:
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    aes256KeyExpansion(&state.aes256, objKey, objKeyLength, gTrue);
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    for (i = 0; i < 16; ++i) {
      state.aes256.cbc[i] = str->getChar();
    }
    state.aes256.bufIdx = 16;
    break;
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  case cryptNone:
    break;
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  }
}

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int DecryptStream::lookChar() {
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  Guchar in[16];
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  int c;

  if (nextCharBuff != EOF)
    return nextCharBuff;
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  c = EOF; // make gcc happy
  switch (algo) {
  case cryptRC4:
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    if ((c = str->getChar()) != EOF) {
      c = rc4DecryptByte(state.rc4.state, &state.rc4.x, &state.rc4.y, (Guchar)c);
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    }
    break;
  case cryptAES:
    if (state.aes.bufIdx == 16) {
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      if (aesReadBlock(str, in, gFalse)) {
        aesDecryptBlock(&state.aes, in, str->lookChar() == EOF);
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      }
    }
    if (state.aes.bufIdx == 16) {
      c = EOF;
    } else {
      c = state.aes.buf[state.aes.bufIdx++];
    }
    break;
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  case cryptAES256:
    if (state.aes256.bufIdx == 16) {
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      if (aesReadBlock(str, in, gFalse)) {
        aes256DecryptBlock(&state.aes256, in, str->lookChar() == EOF);
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      }
    }
    if (state.aes256.bufIdx == 16) {
      c = EOF;
    } else {
      c = state.aes256.buf[state.aes256.bufIdx++];
    }
    break;
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  case cryptNone:
    break;
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  }
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  return (nextCharBuff = c);
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}

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//------------------------------------------------------------------------
// RC4-compatible decryption
//------------------------------------------------------------------------

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static void rc4InitKey(Guchar *key, int keyLen, Guchar *state) {
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  Guchar index1, index2;
  Guchar t;
  int i;

  for (i = 0; i < 256; ++i)
    state[i] = i;
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  if (unlikely(keyLen == 0))
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    return;

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  index1 = index2 = 0;
  for (i = 0; i < 256; ++i) {
    index2 = (key[index1] + state[i] + index2) % 256;
    t = state[i];
    state[i] = state[index2];
    state[index2] = t;
    index1 = (index1 + 1) % keyLen;
  }
}

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static Guchar rc4DecryptByte(Guchar *state, Guchar *x, Guchar *y, Guchar c) {
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  Guchar x1, y1, tx, ty;

  x1 = *x = (*x + 1) % 256;
  y1 = *y = (state[*x] + *y) % 256;
  tx = state[x1];
  ty = state[y1];
  state[x1] = ty;
  state[y1] = tx;
  return c ^ state[(tx + ty) % 256];
}

610 611 612 613
//------------------------------------------------------------------------
// AES decryption
//------------------------------------------------------------------------

614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639
// Returns gFalse if EOF was reached, gTrue otherwise
static GBool aesReadBlock(Stream *str, Guchar *in, GBool addPadding)
{
  int c, i;

  for (i = 0; i < 16; ++i) {
    if ((c = str->getChar()) != EOF) {
      in[i] = (Guchar)c;
    } else {
      break;
    }
  }

  if (i == 16) {
    return gTrue;
  } else {
    if (addPadding) {
      c = 16 - i;
      while (i < 16) {
        in[i++] = (Guchar)c;
      }
    }
    return gFalse;
  }
}

640
static const Guchar sbox[256] = {
641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658
  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

659
static const Guchar invSbox[256] = {
660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677
  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
  0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
  0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
  0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
  0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
  0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
  0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
  0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
  0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
  0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
  0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
  0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
  0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
  0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
  0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};

678
static const Guint rcon[11] = {
679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702
  0x00000000, // unused
  0x01000000,
  0x02000000,
  0x04000000,
  0x08000000,
  0x10000000,
  0x20000000,
  0x40000000,
  0x80000000,
  0x1b000000,
  0x36000000
};

static inline Guint subWord(Guint x) {
  return (sbox[x >> 24] << 24)
         | (sbox[(x >> 16) & 0xff] << 16)
         | (sbox[(x >> 8) & 0xff] << 8)
         | sbox[x & 0xff];
}

static inline Guint rotWord(Guint x) {
  return ((x << 8) & 0xffffffff) | (x >> 24);
}

703 704 705 706 707 708 709 710
static inline void subBytes(Guchar *state) {
  int i;

  for (i = 0; i < 16; ++i) {
    state[i] = sbox[state[i]];
  }
}

711 712 713 714 715 716 717 718
static inline void invSubBytes(Guchar *state) {
  int i;

  for (i = 0; i < 16; ++i) {
    state[i] = invSbox[state[i]];
  }
}

719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
static inline void shiftRows(Guchar *state) {
  Guchar t;

  t = state[4];
  state[4] = state[5];
  state[5] = state[6];
  state[6] = state[7];
  state[7] = t;

  t = state[8];
  state[8] = state[10];
  state[10] = t;
  t = state[9];
  state[9] = state[11];
  state[11] = t;

  t = state[15];
  state[15] = state[14];
  state[14] = state[13];
  state[13] = state[12];
  state[12] = t;
}

742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764
static inline void invShiftRows(Guchar *state) {
  Guchar t;

  t = state[7];
  state[7] = state[6];
  state[6] = state[5];
  state[5] = state[4];
  state[4] = t;

  t = state[8];
  state[8] = state[10];
  state[10] = t;
  t = state[9];
  state[9] = state[11];
  state[11] = t;

  t = state[12];
  state[12] = state[13];
  state[13] = state[14];
  state[14] = state[15];
  state[15] = t;
}

765 766 767 768 769 770 771 772 773 774 775
// {02} \cdot s
static inline Guchar mul02(Guchar s) {
  return (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
}

// {03} \cdot s
static inline Guchar mul03(Guchar s) {
  Guchar s2 = (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
  return s ^ s2;
}

776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815
// {09} \cdot s
static inline Guchar mul09(Guchar s) {
  Guchar s2, s4, s8;

  s2 = (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
  s4 = (s2 & 0x80) ? ((s2 << 1) ^ 0x1b) : (s2 << 1);
  s8 = (s4 & 0x80) ? ((s4 << 1) ^ 0x1b) : (s4 << 1);
  return s ^ s8;
}

// {0b} \cdot s
static inline Guchar mul0b(Guchar s) {
  Guchar s2, s4, s8;

  s2 = (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
  s4 = (s2 & 0x80) ? ((s2 << 1) ^ 0x1b) : (s2 << 1);
  s8 = (s4 & 0x80) ? ((s4 << 1) ^ 0x1b) : (s4 << 1);
  return s ^ s2 ^ s8;
}

// {0d} \cdot s
static inline Guchar mul0d(Guchar s) {
  Guchar s2, s4, s8;

  s2 = (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
  s4 = (s2 & 0x80) ? ((s2 << 1) ^ 0x1b) : (s2 << 1);
  s8 = (s4 & 0x80) ? ((s4 << 1) ^ 0x1b) : (s4 << 1);
  return s ^ s4 ^ s8;
}

// {0e} \cdot s
static inline Guchar mul0e(Guchar s) {
  Guchar s2, s4, s8;

  s2 = (s & 0x80) ? ((s << 1) ^ 0x1b) : (s << 1);
  s4 = (s2 & 0x80) ? ((s2 << 1) ^ 0x1b) : (s2 << 1);
  s8 = (s4 & 0x80) ? ((s4 << 1) ^ 0x1b) : (s4 << 1);
  return s2 ^ s4 ^ s8;
}

816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831
static inline void mixColumns(Guchar *state) {
  int c;
  Guchar s0, s1, s2, s3;

  for (c = 0; c < 4; ++c) {
    s0 = state[c];
    s1 = state[4+c];
    s2 = state[8+c];
    s3 = state[12+c];
    state[c] =    mul02(s0) ^ mul03(s1) ^ s2 ^ s3;
    state[4+c] =  s0 ^ mul02(s1) ^ mul03(s2) ^ s3;
    state[8+c] =  s0 ^ s1 ^ mul02(s2) ^ mul03(s3);
    state[12+c] = mul03(s0) ^ s1 ^ s2 ^ mul02(s3);
  }
}

832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875
static inline void invMixColumns(Guchar *state) {
  int c;
  Guchar s0, s1, s2, s3;

  for (c = 0; c < 4; ++c) {
    s0 = state[c];
    s1 = state[4+c];
    s2 = state[8+c];
    s3 = state[12+c];
    state[c] =    mul0e(s0) ^ mul0b(s1) ^ mul0d(s2) ^ mul09(s3);
    state[4+c] =  mul09(s0) ^ mul0e(s1) ^ mul0b(s2) ^ mul0d(s3);
    state[8+c] =  mul0d(s0) ^ mul09(s1) ^ mul0e(s2) ^ mul0b(s3);
    state[12+c] = mul0b(s0) ^ mul0d(s1) ^ mul09(s2) ^ mul0e(s3);
  }
}

static inline void invMixColumnsW(Guint *w) {
  int c;
  Guchar s0, s1, s2, s3;

  for (c = 0; c < 4; ++c) {
    s0 = w[c] >> 24;
    s1 = w[c] >> 16;
    s2 = w[c] >> 8;
    s3 = w[c];
    w[c] = ((mul0e(s0) ^ mul0b(s1) ^ mul0d(s2) ^ mul09(s3)) << 24)
           | ((mul09(s0) ^ mul0e(s1) ^ mul0b(s2) ^ mul0d(s3)) << 16)
           | ((mul0d(s0) ^ mul09(s1) ^ mul0e(s2) ^ mul0b(s3)) << 8)
           | (mul0b(s0) ^ mul0d(s1) ^ mul09(s2) ^ mul0e(s3));
  }
}

static inline void addRoundKey(Guchar *state, Guint *w) {
  int c;

  for (c = 0; c < 4; ++c) {
    state[c] ^= w[c] >> 24;
    state[4+c] ^= w[c] >> 16;
    state[8+c] ^= w[c] >> 8;
    state[12+c] ^= w[c];
  }
}

static void aesKeyExpansion(DecryptAESState *s,
876
			    Guchar *objKey, int /*objKeyLen*/, GBool decrypt) {
877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892
  Guint temp;
  int i, round;

  //~ this assumes objKeyLen == 16

  for (i = 0; i < 4; ++i) {
    s->w[i] = (objKey[4*i] << 24) + (objKey[4*i+1] << 16) +
              (objKey[4*i+2] << 8) + objKey[4*i+3];
  }
  for (i = 4; i < 44; ++i) {
    temp = s->w[i-1];
    if (!(i & 3)) {
      temp = subWord(rotWord(temp)) ^ rcon[i/4];
    }
    s->w[i] = s->w[i-4] ^ temp;
  }
893 894 895 896 897 898

  /* In case of decryption, adjust the key schedule for the equivalent inverse cipher */
  if (decrypt) {
    for (round = 1; round <= 9; ++round) {
      invMixColumnsW(&s->w[round * 4]);
    }
899 900 901
  }
}

902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938
static void aesEncryptBlock(DecryptAESState *s, Guchar *in) {
  int c, round;

  // initial state (input is xor'd with previous output because of CBC)
  for (c = 0; c < 4; ++c) {
    s->state[c] = in[4*c] ^ s->buf[4*c];
    s->state[4+c] = in[4*c+1] ^ s->buf[4*c+1];
    s->state[8+c] = in[4*c+2] ^ s->buf[4*c+2];
    s->state[12+c] = in[4*c+3] ^ s->buf[4*c+3];
  }

  // round 0
  addRoundKey(s->state, &s->w[0]);

  // rounds 1-9
  for (round = 1; round <= 9; ++round) {
    subBytes(s->state);
    shiftRows(s->state);
    mixColumns(s->state);
    addRoundKey(s->state, &s->w[round * 4]);
  }

  // round 10
  subBytes(s->state);
  shiftRows(s->state);
  addRoundKey(s->state, &s->w[10 * 4]);

  for (c = 0; c < 4; ++c) {
    s->buf[4*c] = s->state[c];
    s->buf[4*c+1] = s->state[4+c];
    s->buf[4*c+2] = s->state[8+c];
    s->buf[4*c+3] = s->state[12+c];
  }

  s->bufIdx = 0;
}

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static void aesDecryptBlock(DecryptAESState *s, Guchar *in, GBool last) {
  int c, round, n, i;

  // initial state
  for (c = 0; c < 4; ++c) {
    s->state[c] = in[4*c];
    s->state[4+c] = in[4*c+1];
    s->state[8+c] = in[4*c+2];
    s->state[12+c] = in[4*c+3];
  }

  // round 0
  addRoundKey(s->state, &s->w[10 * 4]);

  // rounds 1-9
  for (round = 9; round >= 1; --round) {
    invSubBytes(s->state);
    invShiftRows(s->state);
    invMixColumns(s->state);
    addRoundKey(s->state, &s->w[round * 4]);
  }

  // round 10
  invSubBytes(s->state);
  invShiftRows(s->state);
  addRoundKey(s->state, &s->w[0]);

  // CBC
  for (c = 0; c < 4; ++c) {
    s->buf[4*c] = s->state[c] ^ s->cbc[4*c];
    s->buf[4*c+1] = s->state[4+c] ^ s->cbc[4*c+1];
    s->buf[4*c+2] = s->state[8+c] ^ s->cbc[4*c+2];
    s->buf[4*c+3] = s->state[12+c] ^ s->cbc[4*c+3];
  }

  // save the input block for the next CBC
  for (i = 0; i < 16; ++i) {
    s->cbc[i] = in[i];
  }

  // remove padding
  s->bufIdx = 0;
  if (last) {
    n = s->buf[15];
983 984 985 986 987 988 989 990 991 992 993 994 995 996 997
    if (n < 1 || n > 16) { // this should never happen
      n = 16;
    }
    for (i = 15; i >= n; --i) {
      s->buf[i] = s->buf[i-n];
    }
    s->bufIdx = n;
  }
}

//------------------------------------------------------------------------
// AES-256 decryption
//------------------------------------------------------------------------

static void aes256KeyExpansion(DecryptAES256State *s,
998
			       Guchar *objKey, int objKeyLen, GBool decrypt) {
999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016
  Guint temp;
  int i, round;

  //~ this assumes objKeyLen == 32

  for (i = 0; i < 8; ++i) {
    s->w[i] = (objKey[4*i] << 24) + (objKey[4*i+1] << 16) +
              (objKey[4*i+2] << 8) + objKey[4*i+3];
  }
  for (i = 8; i < 60; ++i) {
    temp = s->w[i-1];
    if ((i & 7) == 0) {
      temp = subWord(rotWord(temp)) ^ rcon[i/8];
    } else if ((i & 7) == 4) {
      temp = subWord(temp);
    }
    s->w[i] = s->w[i-8] ^ temp;
  }
1017 1018 1019 1020 1021 1022

  /* In case of decryption, adjust the key schedule for the equivalent inverse cipher */
  if (decrypt) {
    for (round = 1; round <= 13; ++round) {
      invMixColumnsW(&s->w[round * 4]);
    }
1023 1024 1025
  }
}

1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062
static void aes256EncryptBlock(DecryptAES256State *s, Guchar *in) {
  int c, round;

  // initial state (input is xor'd with previous output because of CBC)
  for (c = 0; c < 4; ++c) {
    s->state[c] = in[4*c] ^ s->buf[4*c];
    s->state[4+c] = in[4*c+1] ^ s->buf[4*c+1];
    s->state[8+c] = in[4*c+2] ^ s->buf[4*c+2];
    s->state[12+c] = in[4*c+3] ^ s->buf[4*c+3];
  }

  // round 0
  addRoundKey(s->state, &s->w[0]);

  // rounds 1-13
  for (round = 1; round <= 13; ++round) {
    subBytes(s->state);
    shiftRows(s->state);
    mixColumns(s->state);
    addRoundKey(s->state, &s->w[round * 4]);
  }

  // round 14
  subBytes(s->state);
  shiftRows(s->state);
  addRoundKey(s->state, &s->w[14 * 4]);

  for (c = 0; c < 4; ++c) {
    s->buf[4*c] = s->state[c];
    s->buf[4*c+1] = s->state[4+c];
    s->buf[4*c+2] = s->state[8+c];
    s->buf[4*c+3] = s->state[12+c];
  }

  s->bufIdx = 0;
}

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static void aes256DecryptBlock(DecryptAES256State *s, Guchar *in, GBool last) {
  int c, round, n, i;

  // initial state
  for (c = 0; c < 4; ++c) {
    s->state[c] = in[4*c];
    s->state[4+c] = in[4*c+1];
    s->state[8+c] = in[4*c+2];
    s->state[12+c] = in[4*c+3];
  }

  // round 0
  addRoundKey(s->state, &s->w[14 * 4]);

  // rounds 13-1
  for (round = 13; round >= 1; --round) {
    invSubBytes(s->state);
    invShiftRows(s->state);
    invMixColumns(s->state);
    addRoundKey(s->state, &s->w[round * 4]);
  }

  // round 14
  invSubBytes(s->state);
  invShiftRows(s->state);
  addRoundKey(s->state, &s->w[0]);

  // CBC
  for (c = 0; c < 4; ++c) {
    s->buf[4*c] = s->state[c] ^ s->cbc[4*c];
    s->buf[4*c+1] = s->state[4+c] ^ s->cbc[4*c+1];
    s->buf[4*c+2] = s->state[8+c] ^ s->cbc[4*c+2];
    s->buf[4*c+3] = s->state[12+c] ^ s->cbc[4*c+3];
  }

  // save the input block for the next CBC
  for (i = 0; i < 16; ++i) {
    s->cbc[i] = in[i];
  }

  // remove padding
  s->bufIdx = 0;
  if (last) {
    n = s->buf[15];
    if (n < 1 || n > 16) { // this should never happen
      n = 16;
    }
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    for (i = 15; i >= n; --i) {
      s->buf[i] = s->buf[i-n];
    }
    s->bufIdx = n;
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    if (n > 16)
    {
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      error(errSyntaxError, -1, "Reducing bufIdx from {0:d} to 16 to not crash", n);
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      s->bufIdx = 16;
    }
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  }
}

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//------------------------------------------------------------------------
// MD5 message digest
//------------------------------------------------------------------------

// this works around a bug in older Sun compilers
static inline Gulong rotateLeft(Gulong x, int r) {
  x &= 0xffffffff;
  return ((x << r) | (x >> (32 - r))) & 0xffffffff;
}

static inline Gulong md5Round1(Gulong a, Gulong b, Gulong c, Gulong d,
			       Gulong Xk,  Gulong s, Gulong Ti) {
  return b + rotateLeft((a + ((b & c) | (~b & d)) + Xk + Ti), s);
}

static inline Gulong md5Round2(Gulong a, Gulong b, Gulong c, Gulong d,
			       Gulong Xk,  Gulong s, Gulong Ti) {
  return b + rotateLeft((a + ((b & d) | (c & ~d)) + Xk + Ti), s);
}

static inline Gulong md5Round3(Gulong a, Gulong b, Gulong c, Gulong d,
			       Gulong Xk,  Gulong s, Gulong Ti) {
  return b + rotateLeft((a + (b ^ c ^ d) + Xk + Ti), s);
}

static inline Gulong md5Round4(Gulong a, Gulong b, Gulong c, Gulong d,
			       Gulong Xk,  Gulong s, Gulong Ti) {
  return b + rotateLeft((a + (c ^ (b | ~d)) + Xk + Ti), s);
}

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void md5(Guchar *msg, int msgLen, Guchar *digest) {
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  Gulong x[16];
  Gulong a, b, c, d, aa, bb, cc, dd;
  int n64;
  int i, j, k;

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  // sanity check
  if (msgLen < 0) {
    return;
  }

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  // compute number of 64-byte blocks
  // (length + pad byte (0x80) + 8 bytes for length)
  n64 = (msgLen + 1 + 8 + 63) / 64;

  // initialize a, b, c, d
  a = 0x67452301;
  b = 0xefcdab89;
  c = 0x98badcfe;
  d = 0x10325476;

  // loop through blocks
  k = 0;
  for (i = 0; i < n64; ++i) {

    // grab a 64-byte block
    for (j = 0; j < 16 && k < msgLen - 3; ++j, k += 4)
      x[j] = (((((msg[k+3] << 8) + msg[k+2]) << 8) + msg[k+1]) << 8) + msg[k];
    if (i == n64 - 1) {
      if (k == msgLen - 3)
	x[j] = 0x80000000 + (((msg[k+2] << 8) + msg[k+1]) << 8) + msg[k];
      else if (k == msgLen - 2)
	x[j] = 0x800000 + (msg[k+1] << 8) + msg[k];
      else if (k == msgLen - 1)
	x[j] = 0x8000 + msg[k];
      else
	x[j] = 0x80;
      ++j;
      while (j < 16)
	x[j++] = 0;
      x[14] = msgLen << 3;
    }

    // save a, b, c, d
    aa = a;
    bb = b;
    cc = c;
    dd = d;

    // round 1
    a = md5Round1(a, b, c, d, x[0],   7, 0xd76aa478);
    d = md5Round1(d, a, b, c, x[1],  12, 0xe8c7b756);
    c = md5Round1(c, d, a, b, x[2],  17, 0x242070db);
    b = md5Round1(b, c, d, a, x[3],  22, 0xc1bdceee);
    a = md5Round1(a, b, c, d, x[4],   7, 0xf57c0faf);
    d = md5Round1(d, a, b, c, x[5],  12, 0x4787c62a);
    c = md5Round1(c, d, a, b, x[6],  17, 0xa8304613);
    b = md5Round1(b, c, d, a, x[7],  22, 0xfd469501);
    a = md5Round1(a, b, c, d, x[8],   7, 0x698098d8);
    d = md5Round1(d, a, b, c, x[9],  12, 0x8b44f7af);
    c = md5Round1(c, d, a, b, x[10], 17, 0xffff5bb1);
    b = md5Round1(b, c, d, a, x[11], 22, 0x895cd7be);
    a = md5Round1(a, b, c, d, x[12],  7, 0x6b901122);
    d = md5Round1(d, a, b, c, x[13], 12, 0xfd987193);
    c = md5Round1(c, d, a, b, x[14], 17, 0xa679438e);
    b = md5Round1(b, c, d, a, x[15], 22, 0x49b40821);

    // round 2
    a = md5Round2(a, b, c, d, x[1],   5, 0xf61e2562);
    d = md5Round2(d, a, b, c, x[6],   9, 0xc040b340);
    c = md5Round2(c, d, a, b, x[11], 14, 0x265e5a51);
    b = md5Round2(b, c, d, a, x[0],  20, 0xe9b6c7aa);
    a = md5Round2(a, b, c, d, x[5],   5, 0xd62f105d);
    d = md5Round2(d, a, b, c, x[10],  9, 0x02441453);
    c = md5Round2(c, d, a, b, x[15], 14, 0xd8a1e681);
    b = md5Round2(b, c, d, a, x[4],  20, 0xe7d3fbc8);
    a = md5Round2(a, b, c, d, x[9],   5, 0x21e1cde6);
    d = md5Round2(d, a, b, c, x[14],  9, 0xc33707d6);
    c = md5Round2(c, d, a, b, x[3],  14, 0xf4d50d87);
    b = md5Round2(b, c, d, a, x[8],  20, 0x455a14ed);
    a = md5Round2(a, b, c, d, x[13],  5, 0xa9e3e905);
    d = md5Round2(d, a, b, c, x[2],   9, 0xfcefa3f8);
    c = md5Round2(c, d, a, b, x[7],  14, 0x676f02d9);
    b = md5Round2(b, c, d, a, x[12], 20, 0x8d2a4c8a);

    // round 3
    a = md5Round3(a, b, c, d, x[5],   4, 0xfffa3942);
    d = md5Round3(d, a, b, c, x[8],  11, 0x8771f681);
    c = md5Round3(c, d, a, b, x[11], 16, 0x6d9d6122);
    b = md5Round3(b, c, d, a, x[14], 23, 0xfde5380c);
    a = md5Round3(a, b, c, d, x[1],   4, 0xa4beea44);
    d = md5Round3(d, a, b, c, x[4],  11, 0x4bdecfa9);
    c = md5Round3(c, d, a, b, x[7],  16, 0xf6bb4b60);
    b = md5Round3(b, c, d, a, x[10], 23, 0xbebfbc70);
    a = md5Round3(a, b, c, d, x[13],  4, 0x289b7ec6);
    d = md5Round3(d, a, b, c, x[0],  11, 0xeaa127fa);
    c = md5Round3(c, d, a, b, x[3],  16, 0xd4ef3085);
    b = md5Round3(b, c, d, a, x[6],  23, 0x04881d05);
    a = md5Round3(a, b, c, d, x[9],   4, 0xd9d4d039);
    d = md5Round3(d, a, b, c, x[12], 11, 0xe6db99e5);
    c = md5Round3(c, d, a, b, x[15], 16, 0x1fa27cf8);
    b = md5Round3(b, c, d, a, x[2],  23, 0xc4ac5665);

    // round 4
    a = md5Round4(a, b, c, d, x[0],   6, 0xf4292244);
    d = md5Round4(d, a, b, c, x[7],  10, 0x432aff97);
    c = md5Round4(c, d, a, b, x[14], 15, 0xab9423a7);
    b = md5Round4(b, c, d, a, x[5],  21, 0xfc93a039);
    a = md5Round4(a, b, c, d, x[12],  6, 0x655b59c3);
    d = md5Round4(d, a, b, c, x[3],  10, 0x8f0ccc92);
    c = md5Round4(c, d, a, b, x[10], 15, 0xffeff47d);
    b = md5Round4(b, c, d, a, x[1],  21, 0x85845dd1);
    a = md5Round4(a, b, c, d, x[8],   6, 0x6fa87e4f);
    d = md5Round4(d, a, b, c, x[15], 10, 0xfe2ce6e0);
    c = md5Round4(c, d, a, b, x[6],  15, 0xa3014314);
    b = md5Round4(b, c, d, a, x[13], 21, 0x4e0811a1);
    a = md5Round4(a, b, c, d, x[4],   6, 0xf7537e82);
    d = md5Round4(d, a, b, c, x[11], 10, 0xbd3af235);
    c = md5Round4(c, d, a, b, x[2],  15, 0x2ad7d2bb);
    b = md5Round4(b, c, d, a, x[9],  21, 0xeb86d391);

    // increment a, b, c, d
    a += aa;
    b += bb;
    c += cc;
    d += dd;
  }

  // break digest into bytes
  digest[0] = (Guchar)(a & 0xff);
  digest[1] = (Guchar)((a >>= 8) & 0xff);
  digest[2] = (Guchar)((a >>= 8) & 0xff);
  digest[3] = (Guchar)((a >>= 8) & 0xff);
  digest[4] = (Guchar)(b & 0xff);
  digest[5] = (Guchar)((b >>= 8) & 0xff);
  digest[6] = (Guchar)((b >>= 8) & 0xff);
  digest[7] = (Guchar)((b >>= 8) & 0xff);
  digest[8] = (Guchar)(c & 0xff);
  digest[9] = (Guchar)((c >>= 8) & 0xff);
  digest[10] = (Guchar)((c >>= 8) & 0xff);
  digest[11] = (Guchar)((c >>= 8) & 0xff);
  digest[12] = (Guchar)(d & 0xff);
  digest[13] = (Guchar)((d >>= 8) & 0xff);
  digest[14] = (Guchar)((d >>= 8) & 0xff);
  digest[15] = (Guchar)((d >>= 8) & 0xff);
}
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//------------------------------------------------------------------------
// SHA-256 hash
//------------------------------------------------------------------------

static Guint sha256K[64] = {
  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};

static inline Guint rotr(Guint x, Guint n) {
  return (x >> n) | (x << (32 - n));
}

static inline Guint sha256Ch(Guint x, Guint y, Guint z) {
  return (x & y) ^ (~x & z);
}

static inline Guint sha256Maj(Guint x, Guint y, Guint z) {
  return (x & y) ^ (x & z) ^ (y & z);
}

static inline Guint sha256Sigma0(Guint x) {
  return rotr(x, 2) ^ rotr(x, 13) ^ rotr(x, 22);
}

static inline Guint sha256Sigma1(Guint x) {
  return rotr(x, 6) ^ rotr(x, 11) ^ rotr(x, 25);
}

static inline Guint sha256sigma0(Guint x) {
  return rotr(x, 7) ^ rotr(x, 18) ^ (x >> 3);
}

static inline Guint sha256sigma1(Guint x) {
  return rotr(x, 17) ^ rotr(x, 19) ^ (x >> 10);
}

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static void sha256HashBlock(Guchar *blk, Guint *H) {
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  Guint W[64];
  Guint a, b, c, d, e, f, g, h;
  Guint T1, T2;
  Guint t;

  // 1. prepare the message schedule
  for (t = 0; t < 16; ++t) {
    W[t] = (blk[t*4] << 24) |
           (blk[t*4 + 1] << 16) |
           (blk[t*4 + 2] << 8) |
           blk[t*4 + 3];
  }
  for (t = 16; t < 64; ++t) {
    W[t] = sha256sigma1(W[t-2]) + W[t-7] + sha256sigma0(W[t-15]) + W[t-16];
  }

  // 2. initialize the eight working variables
  a = H[0];
  b = H[1];
  c = H[2];
  d = H[3];
  e = H[4];
  f = H[5];
  g = H[6];
  h = H[7];

  // 3.
  for (t = 0; t < 64; ++t) {
    T1 = h + sha256Sigma1(e) + sha256Ch(e,f,g) + sha256K[t] + W[t];
    T2 = sha256Sigma0(a) + sha256Maj(a,b,c);
    h = g;
    g = f;
    f = e;
    e = d + T1;
    d = c;
    c = b;
    b = a;
    a = T1 + T2;
  }

  // 4. compute the intermediate hash value
  H[0] += a;
  H[1] += b;
  H[2] += c;
  H[3] += d;
  H[4] += e;
  H[5] += f;
  H[6] += g;
  H[7] += h;
}

static void sha256(Guchar *msg, int msgLen, Guchar *hash) {
  Guchar blk[64];
  Guint H[8];
  int blkLen, i;

  H[0] = 0x6a09e667;
  H[1] = 0xbb67ae85;
  H[2] = 0x3c6ef372;
  H[3] = 0xa54ff53a;
  H[4] = 0x510e527f;
  H[5] = 0x9b05688c;
  H[6] = 0x1f83d9ab;
  H[7] = 0x5be0cd19;

  blkLen = 0;
  for (i = 0; i + 64 <= msgLen; i += 64) {
    sha256HashBlock(msg + i, H);
  }
  blkLen = msgLen - i;
  if (blkLen > 0) {
    memcpy(blk, msg + i, blkLen);
  }

  // pad the message
  blk[blkLen++] = 0x80;
  if (blkLen > 56) {
    while (blkLen < 64) {
      blk[blkLen++] = 0;
    }
    sha256HashBlock(blk, H);
    blkLen = 0;
  }
  while (blkLen < 56) {
    blk[blkLen++] = 0;
  }
  blk[56] = 0;
  blk[57] = 0;
  blk[58] = 0;
  blk[59] = 0;
  blk[60] = (Guchar)(msgLen >> 21);
  blk[61] = (Guchar)(msgLen >> 13);
  blk[62] = (Guchar)(msgLen >> 5);
  blk[63] = (Guchar)(msgLen << 3);
  sha256HashBlock(blk, H);

  // copy the output into the buffer (convert words to bytes)
  for (i = 0; i < 8; ++i) {
    hash[i*4]     = (Guchar)(H[i] >> 24);
    hash[i*4 + 1] = (Guchar)(H[i] >> 16);
    hash[i*4 + 2] = (Guchar)(H[i] >> 8);
    hash[i*4 + 3] = (Guchar)H[i];
  }
}
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//------------------------------------------------------------------------
// SHA-512 hash (see FIPS 180-4)
//------------------------------------------------------------------------
// SHA 384 and SHA 512 use the same sequence of eighty constant 64 bit words.
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static const uint64_t shaK[80] = {
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  0x428a2f98d728ae22ull, 0x7137449123ef65cdull, 0xb5c0fbcfec4d3b2full, 0xe9b5dba58189dbbcull, 0x3956c25bf348b538ull,
  0x59f111f1b605d019ull, 0x923f82a4af194f9bull, 0xab1c5ed5da6d8118ull, 0xd807aa98a3030242ull, 0x12835b0145706fbeull,
  0x243185be4ee4b28cull, 0x550c7dc3d5ffb4e2ull, 0x72be5d74f27b896full, 0x80deb1fe3b1696b1ull, 0x9bdc06a725c71235ull,
  0xc19bf174cf692694ull, 0xe49b69c19ef14ad2ull, 0xefbe4786384f25e3ull, 0x0fc19dc68b8cd5b5ull, 0x240ca1cc77ac9c65ull,
  0x2de92c6f592b0275ull, 0x4a7484aa6ea6e483ull, 0x5cb0a9dcbd41fbd4ull, 0x76f988da831153b5ull, 0x983e5152ee66dfabull,
  0xa831c66d2db43210ull, 0xb00327c898fb213full, 0xbf597fc7beef0ee4ull, 0xc6e00bf33da88fc2ull, 0xd5a79147930aa725ull,
  0x06ca6351e003826full, 0x142929670a0e6e70ull, 0x27b70a8546d22ffcull, 0x2e1b21385c26c926ull, 0x4d2c6dfc5ac42aedull,
  0x53380d139d95b3dfull, 0x650a73548baf63deull, 0x766a0abb3c77b2a8ull, 0x81c2c92e47edaee6ull, 0x92722c851482353bull,
  0xa2bfe8a14cf10364ull, 0xa81a664bbc423001ull, 0xc24b8b70d0f89791ull, 0xc76c51a30654be30ull, 0xd192e819d6ef5218ull,
  0xd69906245565a910ull, 0xf40e35855771202aull, 0x106aa07032bbd1b8ull, 0x19a4c116b8d2d0c8ull, 0x1e376c085141ab53ull,
  0x2748774cdf8eeb99ull, 0x34b0bcb5e19b48a8ull, 0x391c0cb3c5c95a63ull, 0x4ed8aa4ae3418acbull, 0x5b9cca4f7763e373ull,
  0x682e6ff3d6b2b8a3ull, 0x748f82ee5defb2fcull, 0x78a5636f43172f60ull, 0x84c87814a1f0ab72ull, 0x8cc702081a6439ecull,
  0x90befffa23631e28ull, 0xa4506cebde82bde9ull, 0xbef9a3f7b2c67915ull, 0xc67178f2e372532bull, 0xca273eceea26619cull,
  0xd186b8c721c0c207ull, 0xeada7dd6cde0eb1eull, 0xf57d4f7fee6ed178ull, 0x06f067aa72176fbaull, 0x0a637dc5a2c898a6ull,
  0x113f9804bef90daeull, 0x1b710b35131c471bull, 0x28db77f523047d84ull, 0x32caab7b40c72493ull, 0x3c9ebe0a15c9bebcull,
  0x431d67c49c100d4cull, 0x4cc5d4becb3e42b6ull, 0x597f299cfc657e2aull, 0x5fcb6fab3ad6faecull, 0x6c44198c4a475817ull
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};

static inline uint64_t rotr(uint64_t x, uint64_t n) {
  return (x >> n) | (x << (64 - n));
}
static inline uint64_t rotl(uint64_t x, uint64_t n){
  return (x << n) | (x >> (64 - n));
}
static inline uint64_t sha512Ch(uint64_t x, uint64_t y, uint64_t z) {
  return (x & y) ^ (~x & z);
}
static inline uint64_t sha512Maj(uint64_t x, uint64_t y, uint64_t z) {
  return (x & y) ^ (x & z) ^ (y & z);
}
static inline uint64_t sha512Sigma0(uint64_t x) {
  return rotr(x, 28) ^ rotr(x, 34) ^ rotr(x, 39);
}
static inline uint64_t sha512Sigma1(uint64_t x) {
  return rotr(x, 14) ^ rotr(x, 18) ^ rotr(x, 41);
}
static inline uint64_t sha512sigma0(uint64_t x) {
  return rotr(x, 1) ^ rotr(x, 8) ^ (x >> 7);
}
static inline uint64_t sha512sigma1(uint64_t x) {
  return rotr(x, 19) ^ rotr(x, 61) ^ (x >> 6);
}

static void sha512HashBlock(Guchar *blk, uint64_t *H) {
  uint64_t W[80];
  uint64_t a, b, c, d, e, f, g, h;
  uint64_t T1, T2;
  Guint t;

  // 1. prepare the message schedule
  for (t = 0; t < 16; ++t) {
    W[t] = (((uint64_t)blk[t*8] << 56) |
        ((uint64_t)blk[t*8 + 1] << 48) |
        ((uint64_t)blk[t*8 + 2] << 40) |
        ((uint64_t)blk[t*8 + 3] << 32) |
        ((uint64_t)blk[t*8 + 4] << 24) |
        ((uint64_t)blk[t*8 + 5] << 16) |
        ((uint64_t)blk[t*8 + 6] << 8 ) |
        ((uint64_t)blk[t*8 + 7]));
  }
  for (t = 16; t < 80; ++t) {
    W[t] = sha512sigma1(W[t-2]) + W[t-7] + sha512sigma0(W[t-15]) + W[t-16];
  }

  // 2. initialize the eight working variables
  a = H[0];
  b = H[1];
  c = H[2];
  d = H[3];
  e = H[4];
  f = H[5];
  g = H[6];
  h = H[7];

  // 3.
  for (t = 0; t < 80; ++t) {
1536
    T1 = h + sha512Sigma1(e) + sha512Ch(e,f,g) + shaK[t] + W[t];
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    T2 = sha512Sigma0(a) + sha512Maj(a,b,c);
    h = g;
    g = f;
    f = e;
    e = d + T1;
    d = c;
    c = b;
    b = a;
    a = T1 + T2;
  }

  // 4. compute the intermediate hash value
  H[0] += a;
  H[1] += b;
  H[2] += c;
  H[3] += d;
  H[4] += e;
  H[5] += f;
  H[6] += g;
  H[7] += h;
}

static void sha512(Guchar *msg, int msgLen, Guchar *hash) {
  Guchar blk[128];
  uint64_t H[8];
  int blkLen = 0, i;
 // setting the initial hash value.
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  H[0] = 0x6a09e667f3bcc908ull;
  H[1] = 0xbb67ae8584caa73bull;
  H[2] = 0x3c6ef372fe94f82bull;
  H[3] = 0xa54ff53a5f1d36f1ull;
  H[4] = 0x510e527fade682d1ull;
  H[5] = 0x9b05688c2b3e6c1full;
  H[6] = 0x1f83d9abfb41bd6bull;
  H[7] = 0x5be0cd19137e2179ull;
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  for (i = 0; i + 128 <= msgLen; i += 128) {
    sha512HashBlock(msg + i, H);
  }
  blkLen = msgLen - i;
  if (blkLen > 0) {
    memcpy(blk, msg + i, blkLen);
  }

  // pad the message
  blk[blkLen++] = 0x80;
  if (blkLen > 112) {
    while (blkLen < 128) {
      blk[blkLen++] = 0;
    }
    sha512HashBlock(blk, H);
    blkLen = 0;
  }
  while (blkLen < 112) {
    blk[blkLen++] = 0;
  }
  blk[112] = 0;
  blk[113] = 0;
  blk[114] = 0;
  blk[115] = 0;
  blk[116] = 0;
  blk[117] = 0;
  blk[118] = 0;
  blk[119] = 0;
  blk[120] = 0;
  blk[121] = 0;
  blk[122] = 0;
  blk[123] = 0;
  blk[124] = (Guchar)(msgLen >> 21);
  blk[125] = (Guchar)(msgLen >> 13);
  blk[126] = (Guchar)(msgLen >> 5);
  blk[127] = (Guchar)(msgLen << 3);

  sha512HashBlock(blk, H);

  // copy the output into the buffer (convert words to bytes)
  for (i = 0; i < 8; ++i) {
    hash[i*8]     = (Guchar)(H[i] >> 56);
    hash[i*8 + 1] = (Guchar)(H[i] >> 48);
    hash[i*8 + 2] = (Guchar)(H[i] >> 40);
    hash[i*8 + 3] = (Guchar)(H[i] >> 32);
    hash[i*8 + 4] = (Guchar)(H[i] >> 24);
    hash[i*8 + 5] = (Guchar)(H[i] >> 16);
    hash[i*8 + 6] = (Guchar)(H[i] >> 8);
    hash[i*8 + 7] = (Guchar)H[i];
  }
}

//------------------------------------------------------------------------
// SHA-384 (see FIPS 180-4)
//------------------------------------------------------------------------
//The algorithm is defined in the exact same manner as SHA 512 with 2 exceptions
//1.Initial hash value is different.
//2.A 384 bit message digest is obtained by truncating the final hash value.
static void sha384(Guchar *msg, int msgLen, Guchar *hash) {
  Guchar blk[128];
  uint64_t H[8];
  int blkLen, i;
//setting initial hash values
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  H[0] = 0xcbbb9d5dc1059ed8ull;
  H[1] = 0x629a292a367cd507ull;
  H[2] = 0x9159015a3070dd17ull;
  H[3] = 0x152fecd8f70e5939ull;
  H[4] = 0x67332667ffc00b31ull;
  H[5] = 0x8eb44a8768581511ull;
  H[6] = 0xdb0c2e0d64f98fa7ull;
  H[7] = 0x47b5481dbefa4fa4ull;
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//SHA 384 will use the same sha512HashBlock function.
  blkLen = 0;
  for (i = 0; i + 128 <= msgLen; i += 128) {
    sha512HashBlock(msg + i, H);
  }
  blkLen = msgLen - i;
  if (blkLen > 0) {
    memcpy(blk, msg + i, blkLen);
  }

  // pad the message
  blk[blkLen++] = 0x80;
  if (blkLen > 112) {
    while (blkLen < 128) {
      blk[blkLen++] = 0;
    }
    sha512HashBlock(blk, H);
    blkLen = 0;
  }
  while (blkLen < 112) {
    blk[blkLen++] = 0;
  }
  blk[112] = 0;
  blk[113] = 0;
  blk[114] = 0;
  blk[115] = 0;
  blk[116] = 0;
  blk[117] = 0;
  blk[118] = 0;
  blk[119] = 0;
  blk[120] = 0;
  blk[121] = 0;
  blk[122] = 0;
  blk[123] = 0;
  blk[124] = (Guchar)(msgLen >> 21);
  blk[125] = (Guchar)(msgLen >> 13);
  blk[126] = (Guchar)(msgLen >> 5);
  blk[127] = (Guchar)(msgLen << 3);

  sha512HashBlock(blk, H);

 // copy the output into the buffer (convert words to bytes)
 // hash is truncated to 384 bits.
  for (i = 0; i < 6; ++i) {
    hash[i*8]     = (Guchar)(H[i] >> 56);
    hash[i*8 + 1] = (Guchar)(H[i] >> 48);
    hash[i*8 + 2] = (Guchar)(H[i] >> 40);
    hash[i*8 + 3] = (Guchar)(H[i] >> 32);
    hash[i*8 + 4] = (Guchar)(H[i] >> 24);
    hash[i*8 + 5] = (Guchar)(H[i] >> 16);
    hash[i*8 + 6] = (Guchar)(H[i] >> 8);
    hash[i*8 + 7] = (Guchar)H[i];
  }
}

//------------------------------------------------------------------------
// Section 7.6.3.3 (Encryption Key algorithm) of ISO/DIS 32000-2
// Algorithm 2.B:Computing a hash (for revision 6).
//------------------------------------------------------------------------
static void revision6Hash(GooString *inputPassword, Guchar *K, char *userKey) {
  Guchar K1[64*(127+64+48)];
  Guchar  E[64*(127+64+48)];
  DecryptAESState state;
  Guchar aesKey[16];
  Guchar BE16byteNumber[16];

  int inputPasswordLength = inputPassword->getLength();
  int KLength = 32;
  int userKeyLength = 0;
  if (userKey) {
    userKeyLength = 48;
  }
  int sequenceLength;
  int totalLength;
  int rounds = 0;

  while(rounds < 64 || rounds < E[totalLength-1] + 32 ) {
    sequenceLength = inputPasswordLength + KLength + userKeyLength;
    totalLength = 64 * sequenceLength;
    //a.make the string K1
    memcpy(K1, inputPassword, inputPasswordLength);
    memcpy(K1 + inputPasswordLength, K , KLength);
    memcpy(K1 + inputPasswordLength + KLength, userKey, userKeyLength);
    for(int i = 1; i < 64 ; ++i) {
      memcpy(K1 + (i * sequenceLength),K1,sequenceLength);
    }
    //b.Encrypt K1
    memcpy(aesKey,K,16);
    memcpy(state.cbc,K + 16,16);
    memcpy(state.buf, state.cbc, 16); // Copy CBC IV to buf
    state.bufIdx = 0;
    state.paddingReached = gFalse;
    aesKeyExpansion(&state,aesKey,16,gFalse);

    for(int i = 0; i < (4 * sequenceLength); i++) {
      aesEncryptBlock(&state,K1 + (16 * i));
      memcpy(E +(16 * i),state.buf,16);
    }
    memcpy(BE16byteNumber,E,16);
    //c.Taking the first 16 Bytes of E as unsigned big-endian integer,
    //compute the remainder,modulo 3.
    uint64_t N1 = 0,N2 = 0,N3 = 0;
    // N1 contains first 8 bytes of BE16byteNumber
    N1 = ((uint64_t)BE16byteNumber[0] << 56 | (uint64_t)BE16byteNumber[1] << 48
         |(uint64_t)BE16byteNumber[2] << 40 | (uint64_t)BE16byteNumber[3] << 32
         |(uint64_t)BE16byteNumber[4] << 24 | (uint64_t)BE16byteNumber[5] << 16
         |(uint64_t)BE16byteNumber[6] << 8  | (uint64_t)BE16byteNumber[7] );
    uint64_t rem = N1 % 3 ;
    // N2 conatains 0s in higer 4 bytes and 9th to 12 th bytes of BE16byteNumber in lower 4 bytes.
    N2 = ((uint64_t)BE16byteNumber[8] << 24 | (uint64_t)BE16byteNumber[9] << 16
         |(uint64_t)BE16byteNumber[10] << 8 | (uint64_t)BE16byteNumber[11] );
         rem = ((rem << 32 ) | N2) % 3 ;
    // N3 conatains 0s in higer 4 bytes and 13th to 16th bytes of BE16byteNumber in lower 4 bytes.
    N3 = ((uint64_t)BE16byteNumber[12] << 24 | (uint64_t)BE16byteNumber[13] << 16
         |(uint64_t)BE16byteNumber[14] << 8  | (uint64_t)BE16byteNumber[15] );
         rem = ((rem << 32 ) | N3) % 3 ;

    //d.If remainder is 0 perform SHA-256
    if(rem == 0) {
      KLength = 32;
      sha256(E, totalLength, K);
    }
    // remainder is 1 perform SHA-384
    else if(rem == 1) {
      KLength = 48;
      sha384(E, totalLength, K);
    }
    // remainder is 2 perform SHA-512
    else if(rem == 2) {
      KLength = 64;
      sha512(E, totalLength, K);
    }
    rounds++;
  }
  // the first 32 bytes of the final K are the output of the function.
}