<?php
/*
* Copyright (c) 2009-2013 Andre DeMarre
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
namespace Sprout\Helpers\TwoFactor;
/**
* The FixedBitNotation class is for binary to text conversion. It
* can handle many encoding schemes, formally defined or not, that
* use a fixed number of bits to encode each character.
*
* See also:
* https://github.com/ademarre/binary-to-text-php/commit/d44968b55fada4c1fac0902f7595b23d2814b2f2
*/
class FixedBitNotation
{
protected $_chars;
protected $_bitsPerCharacter;
protected $_radix;
protected $_rightPadFinalBits;
protected $_padFinalGroup;
protected $_padCharacter;
protected $_charmap;
/**
* Constructor
*
* @param integer $bitsPerCharacter Bits to use for each encoded
* character
* @param string $chars Base character alphabet
* @param boolean $rightPadFinalBits How to encode last character
* @param boolean $padFinalGroup Add padding to end of encoded
* output
* @param string $padCharacter Character to use for padding
*/
public function __construct(
$bitsPerCharacter, $chars = NULL, $rightPadFinalBits = FALSE,
$padFinalGroup = FALSE, $padCharacter = '=')
{
// Ensure validity of $chars
$chars =
'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-,';
$charLength = 64;
}
// Ensure validity of $bitsPerCharacter
if ($bitsPerCharacter < 1) {
// $bitsPerCharacter must be at least 1
$bitsPerCharacter = 1;
$radix = 2;
} elseif ($charLength < 1 << $bitsPerCharacter) {
// Character length of $chars is too small for $bitsPerCharacter
// Set $bitsPerCharacter to greatest acceptable value
$bitsPerCharacter = 1;
$radix = 2;
while ($charLength >= ($radix <<= 1) && $bitsPerCharacter < 8) {
$bitsPerCharacter++;
}
$radix >>= 1;
} elseif ($bitsPerCharacter > 8) {
// $bitsPerCharacter must not be greater than 8
$bitsPerCharacter = 8;
$radix = 256;
} else {
$radix = 1 << $bitsPerCharacter;
}
$this->_chars = $chars;
$this->_bitsPerCharacter = $bitsPerCharacter;
$this->_radix = $radix;
$this->_rightPadFinalBits = $rightPadFinalBits;
$this->_padFinalGroup = $padFinalGroup;
$this->_padCharacter = $padCharacter[0];
}
/**
* Encode a string
*
* @param string $rawString Binary data to encode
* @return string
*/
public function encode($rawString)
{
// Unpack string into an array of bytes
$bytes = unpack('C*', $rawString); $byteCount = count($bytes);
$encodedString = '';
$bitsRead = 0;
$chars = $this->_chars;
$bitsPerCharacter = $this->_bitsPerCharacter;
$rightPadFinalBits = $this->_rightPadFinalBits;
$padFinalGroup = $this->_padFinalGroup;
$padCharacter = $this->_padCharacter;
// Generate encoded output;
// each loop produces one encoded character
for ($c = 0; $c < $byteCount * 8 / $bitsPerCharacter; $c++) {
// Get the bits needed for this encoded character
if ($bitsRead + $bitsPerCharacter > 8) {
// Not enough bits remain in this byte for the current
// character
// Save the remaining bits before getting the next byte
$oldBitCount = 8 - $bitsRead;
$oldBits = $byte ^ ($byte >> $oldBitCount << $oldBitCount);
$newBitCount = $bitsPerCharacter - $oldBitCount;
if (!$bytes) {
// Last bits; match final character and exit loop
if ($rightPadFinalBits) $oldBits <<= $newBitCount;
$encodedString .= $chars[$oldBits];
if ($padFinalGroup) {
// Array of the lowest common multiples of
// $bitsPerCharacter and 8, divided by 8
$lcmMap = array(1 => 1, 2 => 1, 3 => 3, 4 => 1, 5 => 5, 6 => 3, 7 => 7, 8 => 1);
$bytesPerGroup = $lcmMap[$bitsPerCharacter];
$pads = $bytesPerGroup * 8 / $bitsPerCharacter
* 8 / $bitsPerCharacter);
$encodedString .= str_repeat($padCharacter[0], $pads); }
break;
}
// Get next byte
$bitsRead = 0;
} else {
$oldBitCount = 0;
$newBitCount = $bitsPerCharacter;
}
// Read only the needed bits from this byte
$bits = $byte >> 8 - ($bitsRead + ($newBitCount));
$bits ^= $bits >> $newBitCount << $newBitCount;
$bitsRead += $newBitCount;
if ($oldBitCount) {
// Bits come from seperate bytes, add $oldBits to $bits
$bits = ($oldBits << $newBitCount) | $bits;
}
$encodedString .= $chars[$bits];
}
return $encodedString;
}
/**
* Decode a string
*
* @param string $encodedString Data to decode
* @param boolean $caseSensitive
* @param boolean $strict Returns NULL if $encodedString contains
* an undecodable character
* @return string|NULL
*/
public function decode($encodedString, $caseSensitive = TRUE,
$strict = FALSE)
{
if (!$encodedString || !is_string($encodedString)) { // Empty string, nothing to decode
return '';
}
$chars = $this->_chars;
$bitsPerCharacter = $this->_bitsPerCharacter;
$radix = $this->_radix;
$rightPadFinalBits = $this->_rightPadFinalBits;
$padFinalGroup = $this->_padFinalGroup;
$padCharacter = $this->_padCharacter;
// Get index of encoded characters
if ($this->_charmap) {
$charmap = $this->_charmap;
} else {
for ($i = 0; $i < $radix; $i++) {
$charmap[$chars[$i]] = $i;
}
$this->_charmap = $charmap;
}
// The last encoded character is $encodedString[$lastNotatedIndex]
$lastNotatedIndex = strlen($encodedString) - 1;
// Remove trailing padding characters
while ($encodedString[$lastNotatedIndex] == $padCharacter[0]) {
$encodedString = substr($encodedString, 0, $lastNotatedIndex); $lastNotatedIndex--;
}
$rawString = '';
$byte = 0;
$bitsWritten = 0;
// Convert each encoded character to a series of unencoded bits
for ($c = 0; $c <= $lastNotatedIndex; $c++) {
if (!isset($charmap[$encodedString[$c]]) && !$caseSensitive) { // Encoded character was not found; try other case
if (isset($charmap[$cUpper $charmap[$encodedString[$c]] = $charmap[$cUpper];
} elseif (isset($charmap[$cLower $charmap[$encodedString[$c]] = $charmap[$cLower];
}
}
if (isset($charmap[$encodedString[$c]])) { $bitsNeeded = 8 - $bitsWritten;
$unusedBitCount = $bitsPerCharacter - $bitsNeeded;
// Get the new bits ready
if ($bitsNeeded > $bitsPerCharacter) {
// New bits aren't enough to complete a byte; shift them
// left into position
$newBits = $charmap[$encodedString[$c]] << $bitsNeeded
- $bitsPerCharacter;
$bitsWritten += $bitsPerCharacter;
} elseif ($c != $lastNotatedIndex || $rightPadFinalBits) {
// Zero or more too many bits to complete a byte;
// shift right
$newBits = $charmap[$encodedString[$c]] >> $unusedBitCount;
$bitsWritten = 8; //$bitsWritten += $bitsNeeded;
} else {
// Final bits don't need to be shifted
$newBits = $charmap[$encodedString[$c]];
$bitsWritten = 8;
}
$byte |= $newBits;
if ($bitsWritten == 8 || $c == $lastNotatedIndex) {
// Byte is ready to be written
$rawString .= pack('C', $byte);
if ($c != $lastNotatedIndex) {
// Start the next byte
$bitsWritten = $unusedBitCount;
$byte = ($charmap[$encodedString[$c]]
^ ($newBits << $unusedBitCount)) << 8 - $bitsWritten;
}
}
} elseif ($strict) {
// Unable to decode character; abort
return NULL;
}
}
return $rawString;
}
}
