Data Encoding Tutorials - Herong's Tutorial Examples

∟Base64URL - URL Safe Base64 Encoding

∟PHP Implementation of Base64URL Encoding

This section provides a tutorial example on how to perform Base64URL encoding on binary files using my own implementation in PHP.

Unfortunately, Perl does not provide any default implementation of Base64URL encoding. So we have to do it ourself.

Here is a sample program that allows you to perform Base64URL encoding/decoding and other variations.

<?php 
# Base64_Tool.php
# Copyright (c) 2010 HerongYang.com. All Rights Reserved.

  if (count($argv)<5) {
    print("Usage:\n");
    print("php Base64_Tool.php mode standard input output\n");
    exit;
  }
  $mode = $argv[1];
  $standard = $argv[2];
  $inputFile = $argv[3];
  $outputFile = $argv[4];
  
  $inputStream = fopen($inputFile, "rb");
  $inputBytes = fread($inputStream, filesize($inputFile));
  fclose($inputStream);

  $outputBytes = "";
  if ($mode=="decode") {
    if ($standard=="url") {
      $inputBytes = strtr($inputBytes, "-_", "+/");
    }
    $outputBytes = base64_decode($inputBytes);
  } else {
    $outputBytes = base64_encode($inputBytes);
    if ($standard=="mime") {
       $outputBytes = chunk_split($outputBytes, 76, "\r\n");
    } else if ($standard=="url") {
      $outputBytes = strtr($outputBytes, "+/", "-_");
      $outputBytes = rtrim($outputBytes, "=");
    }
  }
  print($outputBytes."\n");
  
  $outputStream = fopen($outputFile, "wb");
  fwrite($outputStream, $outputBytes);
  fclose($outputStream);
?>

Let's try it with different test cases:

herong$ php Base64_Tool.php encode url A.txt encoded.txt 
QQ

herong$ php Base64_Tool.php decode url encoded.txt decoded.txt   
A

herong$ php Base64_Tool.php encode url lazy_dog.txt encoded.txt
VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wcyBvdmVyIHRoZSBsYXp5IGRvZy4=

herong$ php Base64_Tool.php decode url encoded.txt decoded.txt   
The quick brown fox jumps over the lazy dog.
  
herong$ php Base64_Tool.php encode url url.txt encoded.txt 
aS5odG0_NjQ-NjM

herong$ php Base64_Tool.php decode url encoded.txt decoded.txt   
i.htm?64>63

herong$ php Base64_Tool.php encode standard url.txt encoded.txt 
aS5odG0/NjQ+NjM=

herong$ php Base64_Tool.php decode standard encoded.txt decoded.txt   
i.htm?64>63

herong$ php Base64_Tool.php encode url icon.png encoded.txt 
iVBORw0KGgoAAAANSUhEUgAAABgAAAAY ... HwXgCfzQYOFCEQYGAAAAAElFTkSuQmCC

herong$ php Base64_Tool.php decode url encoded.txt decoded.txt   
?PNG... 

As you can see, my implementation of Base64URL in PHP works as expected.

Table of Contents

 About This Book

 Base64 Encoding

 Base64 Encoding and Decoding Tools

►Base64URL - URL Safe Base64 Encoding

 Base64URL Encoding Algorithm

 Java Built-In Implementation of Base64URL

 Python Built-In Implementation of Base64URL

►PHP Implementation of Base64URL Encoding

 Perl Implementation of Base64URL Encoding

 Base32 Encoding

 URL Encoding, URI Encoding, or Percent Encoding

 UUEncode Encoding

 References

 Full Version in PDF/EPUB

PHP Implementation of Base64URL Encoding - Updated in 2022, by Herong Yang