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refactored hash function to word settings
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@mariahaubner
mariahaubner committed Mar 10, 2017
1 parent 483a167 commit 703e341
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Showing 2 changed files with 204 additions and 186 deletions.
191 changes: 7 additions & 184 deletions src/PhpWord/Metadata/Protection.php
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Original file line number Diff line number Diff line change
Expand Up @@ -25,59 +25,6 @@
*/
class Protection
{
static $algorithmMapping = [
1 => 'md2',
2 => 'md4',
3 => 'md5',
4 => 'sha1',
5 => '', // 'mac' -> not possible with hash()
6 => 'ripemd',
7 => 'ripemd160',
8 => '',
9 => '', //'hmac' -> not possible with hash()
10 => '',
11 => '',
12 => 'sha256',
13 => 'sha384',
14 => 'sha512',
];
static $initialCodeArray = [
0xE1F0,
0x1D0F,
0xCC9C,
0x84C0,
0x110C,
0x0E10,
0xF1CE,
0x313E,
0x1872,
0xE139,
0xD40F,
0x84F9,
0x280C,
0xA96A,
0x4EC3
];
static $encryptionMatrix =
[
[0xAEFC, 0x4DD9, 0x9BB2, 0x2745, 0x4E8A, 0x9D14, 0x2A09],
[0x7B61, 0xF6C2, 0xFDA5, 0xEB6B, 0xC6F7, 0x9DCF, 0x2BBF],
[0x4563, 0x8AC6, 0x05AD, 0x0B5A, 0x16B4, 0x2D68, 0x5AD0],
[0x0375, 0x06EA, 0x0DD4, 0x1BA8, 0x3750, 0x6EA0, 0xDD40],
[0xD849, 0xA0B3, 0x5147, 0xA28E, 0x553D, 0xAA7A, 0x44D5],
[0x6F45, 0xDE8A, 0xAD35, 0x4A4B, 0x9496, 0x390D, 0x721A],
[0xEB23, 0xC667, 0x9CEF, 0x29FF, 0x53FE, 0xA7FC, 0x5FD9],
[0x47D3, 0x8FA6, 0x0F6D, 0x1EDA, 0x3DB4, 0x7B68, 0xF6D0],
[0xB861, 0x60E3, 0xC1C6, 0x93AD, 0x377B, 0x6EF6, 0xDDEC],
[0x45A0, 0x8B40, 0x06A1, 0x0D42, 0x1A84, 0x3508, 0x6A10],
[0xAA51, 0x4483, 0x8906, 0x022D, 0x045A, 0x08B4, 0x1168],
[0x76B4, 0xED68, 0xCAF1, 0x85C3, 0x1BA7, 0x374E, 0x6E9C],
[0x3730, 0x6E60, 0xDCC0, 0xA9A1, 0x4363, 0x86C6, 0x1DAD],
[0x3331, 0x6662, 0xCCC4, 0x89A9, 0x0373, 0x06E6, 0x0DCC],
[0x1021, 0x2042, 0x4084, 0x8108, 0x1231, 0x2462, 0x48C4]
];
static $passwordMaxLength = 15;

/**
* Editing restriction none|readOnly|comments|trackedChanges|forms
*
Expand All @@ -91,28 +38,28 @@ class Protection
*
* @var string
*/
private $password;
private $password = '';

/**
* Number of hashing iterations
*
* @var int
*/
private $spinCount = 100000;
private $spinCount = 0;

/**
* Algorithm-SID according to self::$algorithmMapping
* Algorithm-SID (see to \PhpOffice\PhpWord\Writer\Word2007\Part\Settings::$algorithmMapping)
*
* @var int
*/
private $algorithmSid = 4;
private $algorithmSid = 0;

/**
* Hashed salt
*
* @var string
*/
private $salt;
private $salt = '';

/**
* Create a new instance
Expand Down Expand Up @@ -165,7 +112,7 @@ public function getPassword()
*/
public function setPassword($password)
{
$this->password = $this->getPasswordHash($password);
$this->password = $password;

return $this;
}
Expand Down Expand Up @@ -204,7 +151,7 @@ public function getAlgorithmSid()
}

/**
* Set algorithm-sid (see self::$algorithmMapping)
* Set algorithm-sid (see \PhpOffice\PhpWord\Writer\Word2007\Part\Settings::$algorithmMapping)
*
* @param $algorithmSid
* @return self
Expand Down Expand Up @@ -238,128 +185,4 @@ public function setSalt($salt)

return $this;
}

/**
* Get algorithm from self::$algorithmMapping
*
* @return string
*/
private function getAlgorithm()
{
$algorithm = self::$algorithmMapping[$this->algorithmSid];
if ($algorithm == '') {
$algorithm = 'sha1';
}

return $algorithm;
}

/**
* Create a hashed password that MS Word will be able to work with
*
* @param string $password
* @return string
*/
private function getPasswordHash($password)
{
$orig_encoding = mb_internal_encoding();
mb_internal_encoding("UTF-8");

if (empty($password)) {
return '';
}

$password = mb_substr($password, 0, min(self::$passwordMaxLength, mb_strlen($password)));

// Construct a new NULL-terminated string consisting of single-byte characters:
// Get the single-byte values by iterating through the Unicode characters of the truncated password.
// For each character, if the low byte is not equal to 0, take it. Otherwise, take the high byte.
$pass_utf8 = mb_convert_encoding($password, 'UCS-2LE', 'UTF-8');
$byteChars = [];
for ($i = 0; $i < mb_strlen($password); $i++) {
$byteChars[$i] = ord(substr($pass_utf8, $i * 2, 1));
if ($byteChars[$i] == 0) {
$byteChars[$i] = ord(substr($pass_utf8, $i * 2 + 1, 1));
}
}

// build low-order word and hig-order word and combine them
$combinedKey = $this->buildCombinedKey($byteChars);
// build reversed hexadecimal string
$hex = strtoupper(dechex($combinedKey & 0xFFFFFFFF));
$reversedHex = $hex[6].$hex[7].$hex[4].$hex[5].$hex[2].$hex[3].$hex[0].$hex[1];

$generatedKey = mb_convert_encoding($reversedHex, 'UCS-2LE', 'UTF-8');

// Implementation Notes List:
// Word requires that the initial hash of the password with the salt not be considered in the count.
// The initial hash of salt + key is not included in the iteration count.
$generatedKey = hash($this->getAlgorithm(), base64_decode($this->getSalt()) . $generatedKey, true);
for ($i = 0; $i < $this->getSpinCount(); $i++) {
$generatedKey = hash($this->getAlgorithm(), $generatedKey . pack("CCCC", $i, $i>>8, $i>>16, $i>>24), true);
}
$generatedKey = base64_encode($generatedKey);

mb_internal_encoding($orig_encoding);

return $generatedKey;
}

/**
* Build combined key from low-order word and high-order word
*
* @param array $byteChars -> byte array representation of password
* @return int
*/
private function buildCombinedKey($byteChars)
{
// Compute the high-order word
// Initialize from the initial code array (see above), depending on the passwords length.
$highOrderWord = self::$initialCodeArray[sizeof($byteChars) - 1];

// For each character in the password:
// For every bit in the character, starting with the least significant and progressing to (but excluding)
// the most significant, if the bit is set, XOR the key’s high-order word with the corresponding word from
// the Encryption Matrix
for ($i = 0; $i < sizeof($byteChars); $i++) {
$tmp = self::$passwordMaxLength - sizeof($byteChars) + $i;
$matrixRow = self::$encryptionMatrix[$tmp];
for ($intBit = 0; $intBit < 7; $intBit++) {
if (($byteChars[$i] & (0x0001 << $intBit)) != 0) {
$highOrderWord = ($highOrderWord ^ $matrixRow[$intBit]);
}
}
}

// Compute low-order word
// Initialize with 0
$lowOrderWord = 0;
// For each character in the password, going backwards
for ($i = sizeof($byteChars) - 1; $i >= 0; $i--) {
// low-order word = (((low-order word SHR 14) AND 0x0001) OR (low-order word SHL 1) AND 0x7FFF)) XOR character
$lowOrderWord = (((($lowOrderWord >> 14) & 0x0001) | (($lowOrderWord << 1) & 0x7FFF)) ^ $byteChars[$i]);
}
// Lastly, low-order word = (((low-order word SHR 14) AND 0x0001) OR (low-order word SHL 1) AND 0x7FFF)) XOR strPassword length XOR 0xCE4B.
$lowOrderWord = (((($lowOrderWord >> 14) & 0x0001) | (($lowOrderWord << 1) & 0x7FFF)) ^ sizeof($byteChars) ^ 0xCE4B);

// Combine the Low and High Order Word
return $this->int32(($highOrderWord << 16) + $lowOrderWord);
}

/**
* simulate behaviour of int32
*
* @param int $value
* @return int
*/
private function int32($value)
{
$value = ($value & 0xFFFFFFFF);

if ($value & 0x80000000) {
$value = -((~$value & 0xFFFFFFFF) + 1);
}

return $value;
}
}
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