base64_encode

For anyone interested in the 'base64url' variant encoding, you can use this pair of functions:

<?php
function base64url_encode($data) {
  return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');
}

function base64url_decode($data) {
  return base64_decode(str_pad(strtr($data, '-_', '+/'), strlen($data) % 4, '=', STR_PAD_RIGHT));
}
?>

In PHP 7, the padding issue with base64_decode() is no more - the following is totally fine:function base64_encode_url($string) {    return str_replace(['+','/','='], ['-','_',''], base64_encode($string));}function base64_decode_url($string) {    return base64_decode(str_replace(['-','_'], ['+','/'], $string));}Checked here with random_bytes() and random lengths:https://3v4l.org/aEs4o

gutzmer at usa dot net's ( http://php.net/manual/en/function.base64-encode.php#103849 ) base64url_decode() function doesn't pad longer strings with '='s. Here is a corrected version: <?phpfunction base64url_encode( $data ){  return rtrim( strtr( base64_encode( $data ), '+/', '-_'), '=');}function base64url_decode( $data ){  return base64_decode( strtr( $data, '-_', '+/') . str_repeat('=', 3 - ( 3 + strlen( $data )) % 4 ));}// prooffor( $i = 0, $s = ''; $i < 24; ++$i, $s .= substr("$i", -1 )){  $base64_encoded    = base64_encode(    $s );  $base64url_encoded = base64url_encode( $s );  $base64url_decoded = base64url_decode( $base64url_encoded );  $base64_restored   = strtr( $base64url_encoded, '-_', '+/')                     . str_repeat('=',                         3 - ( 3 + strlen( $base64url_encoded )) % 4                       );  echo "$s<br>$base64url_decoded<br>$base64_encoded<br>$base64_restored<br>$base64url_encoded<br><br>";}?>

Base64 encoding of large files.Base64 encoding converts triples of eight-bit symbols into quadruples of six-bit symbols. Reading the input file in chunks that are a multiple of three bytes in length results in a chunk that can be encoded independently of the rest of the input file. MIME additionally enforces a line length of 76 characters plus the CRLF. 76 characters is enough for 19 quadruples of six-bit symbols thus representing 19 triples of eight-bit symbols. Reading 57 eight-bit symbols provides exactly enough data for a complete MIME-formatted line. Finally, PHP's default buffer size is 8192 bytes - enough for 143 MIME lines' worth of input.So if you read from the input file in chunks of 8151 (=57*143) bytes you will get (up to) 8151 eight-bit symbols, which encode as exactly 10868 six-bit symbols, which then wrap to exactly 143 MIME-formatted lines. There is no need to retain left-over symbols (either six- or eight-bit) from one chunk to the next. Just read a chunk, encode it, write it out, and go on to the next chunk. Obviously the last chunk will probably be shorter, but encoding it is still independent of the rest.<?phpwhile(!feof($input_file)){    $plain = fread($input_file, 57 * 143);    $encoded = base64_encode($plain);    $encoded = chunk_split($encoded, 76, "\r\n");    fwrite($output_file, $encoded);}?>Conversely, each 76-character MIME-formatted line (not counting the trailing CRLF) contains exactly enough data for 57 bytes of output without needing to retain leftover bits that need prepending to the next line. What that means is that each line can be decoded independently of the others, and the decoded chunks can then be concatenated together or written out sequentially. However, this does make the assumption that the encoded data really is MIME-formatted; without that assurance it is necessary to accept that the base64 data won't be so conveniently arranged.

Improvement on "gutzmer at usa dot net", "biziclop at vipmail dot hu", and "ivanm at duck dot com".<?phpfunction base64url_encode($data) {  return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');}function base64url_decode($data) {  return base64_decode(strtr($data, '-_', '+/'));}?>None of the padding for strings longer than 4 characters worked. Padding the decode function with = is unnecessary, and has been since at least PHP 5.4 (as far back as I checked before posting) so I removed it.

Unfortunately my "function" for encoding base64 on-the-fly from 2007 [which has been removed from the manual in favor of this post] had 2 errors!
The first led to an endless loop because of a missing "$feof"-check, the second caused the rare mentioned errors when encoding failed for some reason in larger files, especially when
setting fgets($fh, 2) for example. But lower values then 1024 are bad overall because they slow down the whole process, so 4096 will be fine for all purposes, I guess.
The error was caused by the use of "empty()".

Here comes the corrected version which I have tested for all kind of files and length (up to 4,5 Gb!) without any error:

<?php
$fh = fopen('Input-File', 'rb');
//$fh2 = fopen('Output-File', 'wb');

$cache = '';
$eof = false;

while (1) {

    if (!$eof) {
        if (!feof($fh)) {
            $row = fgets($fh, 4096);
        } else {
            $row = '';
            $eof = true;
        }
    }

    if ($cache !== '')
        $row = $cache.$row;
    elseif ($eof)
        break;

    $b64 = base64_encode($row);
    $put = '';

    if (strlen($b64) < 76) {
        if ($eof) {
            $put = $b64."\n";
            $cache = '';
        } else {
            $cache = $row;
        }

    } elseif (strlen($b64) > 76) {
        do {
            $put .= substr($b64, 0, 76)."\n";
            $b64 = substr($b64, 76);
        } while (strlen($b64) > 76);

        $cache = base64_decode($b64);

    } else {
        if (!$eof && $b64{75} == '=') {
            $cache = $row;
        } else {
            $put = $b64."\n";
            $cache = '';
        }
    }

    if ($put !== '') {
        echo $put;
        //fputs($fh2, $put);
        //fputs($fh2, base64_decode($put));        // for comparing
    }
}

//fclose($fh2);
fclose($fh);
?>

A function I'm using to return local images as base64 encrypted code, i.e. embedding the image source into the html request.This will greatly reduce your page load time as the browser will only need to send one server request for the entire page, rather than multiple requests for the HTML and the images. Requests need to be uploaded and 99% of the world are limited on their upload speed to the server.<?php function base64_encode_image ($filename=string,$filetype=string) {    if ($filename) {        $imgbinary = fread(fopen($filename, "r"), filesize($filename));        return 'data:image/' . $filetype . ';base64,' . base64_encode($imgbinary);    }}?>used as so<style type="text/css">.logo {    background: url("<?php echo base64_encode_image ('img/logo.png','png'); ?>") no-repeat right 5px;}</style>or<img src="<?php echo base64_encode_image ('img/logo.png','png'); ?>"/>

Slight improvement on the padding problem in gutzmer at usa dot net (https://www.php.net/manual/en/function.base64-encode.php#103849) and biziclop at vipmail dot hu (https://www.php.net/manual/en/function.base64-encode.php#121767):<?phpfunction base64url_encode($data) {  return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');}function base64url_decode($data) {  return base64_decode(str_pad(strtr($data, '-_', '+/'), 4 - ((strlen($data) % 4) ?: 4), '=', STR_PAD_RIGHT));}?>

function urlsafe_b64encode($string) {    $data = base64_encode($string);    $data = str_replace(array('+','/','='),array('-','_',''),$data);    return $data;}function urlsafe_b64decode($string) {    $data = str_replace(array('-','_'),array('+','/'),$string);    $mod4 = strlen($data) % 4;    if ($mod4) {        $data .= substr('====', $mod4);    }    return base64_decode($data);}Php version of perl's MIME::Base64::URLSafe, that provides an url-safe base64 string encoding/decoding (compatible with python base64's urlsafe methods)

In lieu with biziclop answer here a small upgrade.<?php/** * convert bin to url friendly base64 */function base64url_encode( string $data ): string{    return rtrim( strtr( base64_encode( $data ), '+/', '-_' ), '=' );}/** * convert url friendly base64 to bin */function base64url_decode( string $data ): string{    return base64_decode( strtr( $data, '-_', '+/' ) . str_repeat( '=', 3 - ( 3 + strlen( $data ) ) % 4 ) );}?>This should symmetrically convert one string and back in a url save manner.

Just a minor tweak of massimo's functions.<?$data = str_replace(array('+','/','='),array('-','_','.'),$data);//replace '=' with '.' instead of with nothing, that way the process is reversible.  '.' is uri-safe according to http://www.w3.org/Addressing/URL/5_URI_BNF.html?>

If the function doesn't exist, this is a messy but effective way of doing it:<?echo bencode("Gabriel Malca");// R2FicmllbCBNYWxjYQ==function bencode($string='') {    $binval = convert_binary_str($string);    $final = "";    $start = 0;    while ($start < strlen($binval)) {        if (strlen(substr($binval,$start)) < 6)            $binval .= str_repeat("0",6-strlen(substr($binval,$start)));        $tmp = bindec(substr($binval,$start,6));        if ($tmp < 26)            $final .= chr($tmp+65);        elseif ($tmp > 25 && $tmp < 52)            $final .= chr($tmp+71);        elseif ($tmp == 62)            $final .= "+";        elseif ($tmp == 63)            $final .= "/";        elseif (!$tmp)            $final .= "A";        else            $final .= chr($tmp-4);        $start += 6;    }    if (strlen($final)%4>0)        $final .= str_repeat("=",4-strlen($final)%4);    return $final;}function convert_binary_str($string) {    if (strlen($string)<=0) return;    $tmp = decbin(ord($string[0]));    $tmp = str_repeat("0",8-strlen($tmp)).$tmp;    return $tmp.convert_binary_str(substr($string,1));}?>

Note that some applications, such as OpenSSL's enc command, require that there be a line break every 64 characters in order for their base64 decode function to work. The following function will take care of this problem:

<?php
function ($encodeMe) {
    $data = base64_encode($encodeMe);
    $datalb = "";
    while (strlen($data) > 64) {
        $datalb .= substr($data, 0, 64) . "\n";
        $data = substr($data,64);
    }
    $datalb .= $data;
    return $datalb;
}
?>

<?php$image = 'example.png';// Read image path, convert to base64 encoding$imageData = base64_encode(file_get_contents($image));// Format the image SRC:  data:{mime};base64,{data};$src = 'data: '.mime_content_type($image).';base64,'.$imageData;// Echo out a sample imageecho "<img src=\"$src\" alt=\"\" />";?>

$data = str_replace(array('+','/','='),array('-','_',),$data); // MIME::Base64::URLSafe implementation       $data = str_replace(array('+','/'),array('-','_'),$data); // Python raise "TypeError: Incorrect padding" if you remove "=" chars when decoding

If you use base64encoded strings as cookie names, make sure you remove '=' characters. At least Internet Explorer refuses cookie names containing '=' characters or urlencoded cookie names containing %xx character replacements. Use the function below to turn base64 encoded strings to bare alphabets (get rid of / and + characters as well)

<?php
function base64clean($base64string)
{
     $base64string = str_replace(array('=','+','/'),'',$base64string); 

     return $base64string;
}
?>

To make base64_encode encode a URL safe string compatible with .net HttpServerUtility.UrlTokenEncode function use this:

<?php
url_safe_base64_encode($string)
  {
    #First base64 encode
    $data = base64_encode($string);

    #Base64 strings can end in several = chars. These need to be translated into a number
    $no_of_eq = substr_count($data, "=");
    $data = str_replace("=", "", $data);
    $data = $data.$no_of_eq;

    #Then replace all non-url safe characters
    $data = str_replace(array('+','/'),array('-','_'),$data);
    return $data;
  }
?>

I needed a simple way to obfuscate auto_increment primary keys in databases when they are visible to users in URIs or API calls. The users should not be able to increment the id in the URL and see the next data record in the database table.My solution (uses modified base64 functions by Tom):function base64url_encode($plainText) {        $base64 = base64_encode($plainText);    $base64url = strtr($base64, '+/=', '-_,');    return $base64url;   }function base64url_decode($plainText) {        $base64url = strtr($plainText, '-_,', '+/=');    $base64 = base64_decode($base64url);    return $base64;   }function encryptId($int, $class='') {        return base64url_encode($int.'-'.substr(sha1($class.$int.encryptionKey), 0, 6));}function decryptId($string, $class='') {        $parts = explode('-', base64url_decode($string));    if (count($parts) != 2) {                return 0;    }        $int = $parts[0];    return substr(sha1($class.$int.encryptionKey), 0, 6) === $parts[1]        ? (int)$int        : 0;}- The optional 2nd argument is the class name, so two equal ids of different tables will not result in two equal obfuscated ids.- encryptionKey is a global secret key for encryption.- decryptId() checks if the second part of the base64 encoded string is correct.

This function supports "base64url" as described in Section 5 of RFC 4648, "Base 64 Encoding with URL and Filename Safe Alphabet"    <?php    function base64url_encode($plainText)    {        $base64 = base64_encode($plainText);        $base64url = strtr($base64, '+/', '-_');        return ($base64url);        }    ?>You may wish to rtrim (or escape) trailing ='s for use in a URI.

You can use base64_encode to transfer image file into string text and then display them. I used this to store my images in a database and display them form there. First I open the files using fread, encoded the result, and stored that result in the database. Useful for creating random images. image.php:<?header(" Content-Type: image/jpeg");header(" Content-Disposition: inline");$sql = "SELECT data FROM image where name='".$img."'";$result = mysql_query($sql);$row = mysql_fetch_row($result);$image = $row[0];echo base64_decode($image);?>And in the html file you put:<img src="image.php?img=test3"  border="0" alt="">Guy Laor

output images into html:<?php$imgfile = "test.gif";$handle = fopen($filename, "r");$imgbinary = fread(fopen($imgfile, "r"), filesize($imgfile));echo '<img src="data:image/gif;base64,' . base64_encode($imgbinary) . '" />';?>gif - data:image/gif;base64,...jpg - data:image/jpeg;base64,...png - data:image/png;base64,...etc.

I am finding a length restriction with base64_encode (or possibly with echo) in PHP 4.3.9.This works ok for me:<?phpecho strlen(str_repeat('-', 3273)); // 3273echo strlen(base64_encode(str_repeat('-', 3273))); // 4364echo base64_encode(str_repeat('-', 3273)); // LS0t repeated?>But change the length to 3274 and the third echo prints nothing.<?phpecho strlen(str_repeat('-', 3274)); // 3274echo strlen(base64_encode(str_repeat('-', 3274))); // 4368echo base64_encode(str_repeat('-', 3274)); // Nothing at all printed?>This has obvious implications if you're wanting to encode a fairly large serialized array and echo it to a form field.

I've used base64_encode and base64_decode for file attachment both in MySQL (using a BLOB field) and MSSQL (using a TEXT field). For MSSQL remember to set in PHP.INI file both mssql.textsize and mssql.textlimit to 2147483647.Here's the code:######### MSSQL(mssql_)/MySQL(mysql_) file attach$val=$HTTP_POST_FILES['lob_upload']['tmp_name'];$valn=$HTTP_POST_FILES['lob_upload']['name'];$valt=$HTTP_POST_FILES['lob_upload']['type'];$data=base64_encode(addslashes(fread(fopen($val, "r"), filesize($val))));mssql_connect("srv","usr","pass") or die ("");mssql_select_db("db") or die ("");$query = "UPDATE $table SET $field='$data', $fieldname='$valn', $fieldtype='$valt' WHERE DocID='$DocID'";$result = mssql_query($query) or die(mssql_error());mssql_close();######### MSSQL(mssql_)/MySQL(mysql_) open file attachedmssql_connect("srv","usr","pass") or die ("");mssql_select_db("db") or die ("");$query = "SELECT $field,$fieldtype FROM $table WHERE DocID='$DocID'";$result = mssql_query($query) or die(mssql_error());$row = mssql_fetch_array($result);header("Content-type: $row[1]");echo stripslashes(base64_decode($row[0]));This strategy is good for Microsoft Word, Acrobat PDF, JPG image and so on (even zipped files!!!)

An even faster way to line-breaks every 64th character is using the chunk_split function:<?php$string = chunk_split(base64_encode($string), 64, "\n");?>

if you for some reason need a base10 / pure-number encode instead, encoding to some combination of 0123456789<?php// base10-encode using the dictionary 0123456789function base10_encode(string $str): string{    $ret = "";    for ($i = 0, $imax = strlen($str); $i < $imax; ++ $i) {        $ret .= str_pad((string) ord($str[$i]), 3, "0", STR_PAD_LEFT);    }    return $ret;}// base10-decode using the dictionary 0123456789function base10_decode(string $str): string{    $ret = "";    for ($i = 0, $imax = strlen($str); $i < $imax; $i += 3) {        // notably here we are using (int) to trim away the zeroes..        $ret .= chr((int) substr($str, $i, 3));    }    return $ret;}?>it is unicode-safe and binary-safe, testing:<?php// simple ascii test: $d=[];$d["raw"]="test";$d["b10"]=base10_encode($d["raw"]); // 116101115116$d["decoded"]=base10_decode($d["b10"]); // test$d["corrupted"]=$d["raw"]!==$d["decoded"]; // falsevar_dump($d);// complex unicode test: $d=[];$d["raw"]="ˈmaʳkʊs kuːn ℕ ⊆ ℕ₀ ⊂ ℤ ⊂ ℚ ⊂ ℝ ⊂ ℂ, ⊥ < a ≠ b ≡ c ≤ d ≪ ⊤ ⇒ (A ⇔ B), Σὲ γνωρίζω ἀπὸ τὴν κόψη Οὐχὶ ταὐτὰ παρίσταταί გთხოვთ ሰማይ አይታረስ ንጉሥ አይከሰስ ᚻᛖ ᚳᚹᚫᚦ ᚦᚫᛏ ᚻᛖ ᛒᚢᛞᛖ ᚩᚾ ᚦᚫᛗ ᛚᚪᚾᛞᛖ ᚾᚩᚱᚦᚹᛖᚪᚱᛞᚢᛗ ᚹᛁᚦ ᚦᚪ ᚹᛖᛥᚫ ";// lets add some chess for good measure$d["raw"].="♔♕♖♗♘♙♚♛♜♝♞🙾🙿";$d["b10"]=base10_encode($d["raw"]); //$d["decoded"]=base10_decode($d["b10"]);$d["corrupted"]=$d["raw"]!==$d["decoded"]; // false, base10 is unicode safe :Dvar_dump($d);// binary safety test:$everything="";for($i=0;$i<=0xFF;++$i){    $everything.=chr($i);}$d=[];$d["raw"]=$everything;$d["b10"]=base10_encode($d["raw"]);$d["decoded"]=base10_decode($d["b10"]);$d["corrupted"]=$d["raw"]!==$d["decoded"]; // false :D base10 is binary safe.var_dump($d);?>

Regarding base64url, you can just use:<?php$encodedUrl = urlencode(base64_encode($string));$decodedUrl = base64_decode(url_decode($string));?>

Note that at least some Windows systems will not print a line of characters longer than a certain length unless it has line breaks of some kind.  So if you base-64 encode a file, print it back for debugging purposes, and see nothing, don't be alarmed.

@gutzmer at usa dot netNice idea! However...The function base64url_decode doesn't pad strings longer than 4 chars.str_pad will only pad the string if the second argument is larger than the length of the original string. So the correct function should be:<?phpfunction base64url_decode($data) {  $len = strlen($data);  return base64_decode(str_pad(strtr($data, '-_', '+/'), $len + $len % 4, '=', STR_PAD_RIGHT));} Note that base64_decode works fine without the padding, that is why your function works.

If you encode text that contains symbols like < > and want to send it in GET query, be sure to urlencode the result of base64_encode, as it sometimes adds a  + (and it's a special symbol) at the end:<?php    echo base64_encode('<html>');?>returns:PGh0bWw+A function like this could also be useful:<?php    function base64_urlencode($str) {        return urlencode(base64_encode($str));    };?>

Using Function:Output for HTML Put:<img src="$self?image=file" border="0" alt="file"><img src="$self?image=folder" border="0" alt="folder">function getimage ($image) {    switch ($image) {    case 'file':        return base64_decode('R0lGODlhEQANAJEDAJmZmf///wAAAP///yH5BAHoAwMALAAAAAARAA0AAAItnIGJxg0B42rsiSvCA/REmXQWhmnih3LUSGaqg35vFbSXucbSabunjnMohq8CADsA');    case 'folder':        return base64_decode('R0lGODlhEQANAJEDAJmZmf///8zMzP///yH5BAHoAwMALAAAAAARAA0AAAIqnI+ZwKwbYgTPtIudlbwLOgCBQJYmCYrn+m3smY5vGc+0a7dhjh7ZbygAADsA');    case 'hidden_file':        return base64_decode('R0lGODlhEQANAJEDAMwAAP///5mZmf///yH5BAHoAwMALAAAAAARAA0AAAItnIGJxg0B42rsiSvCA/REmXQWhmnih3LUSGaqg35vFbSXucbSabunjnMohq8CADsA');    case 'link':        return base64_decode('R0lGODlhEQANAKIEAJmZmf///wAAAMwAAP///wAAAAAAAAAAACH5BAHoAwQALAAAAAARAA0AAAM5SArcrDCCQOuLcIotwgTYUllNOA0DxXkmhY4shM5zsMUKTY8gNgUvW6cnAaZgxMyIM2zBLCaHlJgAADsA');    case 'smiley':        return base64_decode('R0lGODlhEQANAJECAAAAAP//AP///wAAACH5BAHoAwIALAAAAAARAA0AAAIslI+pAu2wDAiz0jWD3hqmBzZf1VCleJQch0rkdnppB3dKZuIygrMRE/oJDwUAOwA=');    case 'arrow':        return base64_decode('R0lGODlhEQANAIABAAAAAP///yH5BAEKAAEALAAAAAARAA0AAAIdjA9wy6gNQ4pwUmav0yvn+hhJiI3mCJ6otrIkxxQAOw==');    }}

Wikipedia has a list of 8 or so variations on the last 2 characters in Base64  (https://en.wikipedia.org/wiki/Base64). The following functions can handle all of them:<?phpfunction base64_encode2($data, $a = "+/=") {    $l = strlen($a);    if ($l === 3) {        return strtr(base64_encode($data), "+/=", $a);    } else if ($l === 2) {        return rtrim(strtr(base64_encode($data), "+/", $a), '=');    } else {        throw new InvalidArgumentException("Argument #2 must be 2 or 3 bytes.");    }}function base64_decode2($data, $strict = false, $a = "+/=") {    $l = strlen($a);    if ($l === 3) {            return base64_decode(strtr($data, $a, "+/="), $strict);    } else if ($l === 2) {        return base64_decode(strtr($data, $a, "+/"), $strict);    } else {        throw new InvalidArgumentException("Argument #2 must be 2 or 3 bytes.");    }}?>Example usage:<?php$decoded = "ABC123";// base64 XML identifier:$encoded = base64_encode2($decoded, "_:");$decoded = base64_decode2($encoded, false, "_:");// base64 URL (RFC 6920):// base64 XML name token:$encoded = base64_encode($decoded, "-_")$decoded = base64_decode($encoded, false, "-_");// modified base64 XML name token:$encoded = base64_encode2($decoded, ".-");$decoded = base64_decode2($encoded, false, ".-");// modified base64 for Regular Expressions:$encoded = base64_encode2($decoded, "!-");$decoded = base64_decode2($encoded, false, "!-");// base64 used in YUI library:$encoded = base64_encode2($decoded, "._-");$decoded = base64_decode2($encoded, false, "._-");?>

shortest base64url_decode (correct version)<?php    function base64_urldecode($data){        return base64_decode(strtr($data,'-_','+/').str_repeat("=", -strlen($data) & 3));}?>