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base64_encode

(PHP 4, PHP 5)

base64_encode — 使用 MIME base64 对数据进行编码

说明

string base64_encode ( string $data )

使用 base64 对 data 进行编码。

设计此种编码是为了使二进制数据可以通过非纯 8-bit 的传输层传输，例如电子邮件的主体。

Base64-encoded 数据要比原始数据多占用 33% 左右的空间。

参数

data: 要编码的数据。

返回值

编码后的字符串数据，或者在失败时返回 FALSE 。

范例

Example #1 base64_encode() 示例

  <?php
$str  =  'This is an encoded string' ;
echo  base64_encode ( $str );
 ?>

以上例程会输出：

VGhpcyBpcyBhbiBlbmNvZGVkIHN0cmluZw==

参见

base64_decode() - 对使用 MIME base64 编码的数据进行解码
chunk_split() - 将字符串分割成小块
convert_uuencode() - 使用 uuencode 编码一个字符串
» RFC 2045 6.8 章节

用户评论:

[#1] Anonymous [2015-09-25 05:26:49]

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:

<?php function 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, "._-"); ?>

[#2] JonyGreen at outlook dot com [2015-09-22 06:28:59]

I'm not a developer, i always use the free online base64 string converter(http://www.online-code.net/base64-string.html) to encode and decode base64.

[#3] sadhooklay [at] gmail [dot] com [2014-12-16 12:26:44]

<?php public static function newToken($n = null, $padding = false) { // Generate a new unique token if (!function_exists('openssl_random_pseudo_bytes')) { // Generate a random pseudo bytes token if openssl_random_pseudo_bytes is available // This is more secure than uniqid, because uniqid relies on microtime, which is predictable $s = pack('a*', openssl_random_pseudo_bytes($n ?: static::RANDOM_LENGTH)); $s = str_replace(["\n", "\r", "\n\r"], '', $s); } else { // Otherwise, fall back to a hashed uniqid $s = substr(hash('sha256', uniqid(null, true)), 0, $n ?: static::RANDOM_LENGTH); } return $padding ? strtr(base64_encode($s), '+/', '-_') : rtrim(strtr(base64_encode($s), '+/', '-_'), '='); } ?>

[#4] Naser Mirzaei [2014-06-24 09:30:25]

<?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,'.$imageData; // Echo out a sample image echo "<img src=\"$src\" alt=\"\" />"; ?>

[#5] nishantmathur62 at gmail dot com [2013-10-15 06:25:41]

<?php $file="test.jpg"; $file_cont=file_get_contents($file); $image=base64_encode($file_cont); $src = 'data:;base64,'.$image; if(copy($src,'test2.jpg')) { echo "success"; } else { echo "Error"; } ?>

[#6] Hayley Watson [2013-04-15 23:35:49]

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.

<?php while(!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.

[#7] Gerard [2013-01-23 13:31:24]

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; } ?>

[#8] luke at lukeoliff.com [2011-08-02 09:27:57]

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'); ?>"/>

[#9] markrose at markrose dot ca [2011-07-07 15:15:39]

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"); ?>

[#10] gutzmer at usa dot net [2011-05-06 09:12:28]

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)); } ?>

[#11] andronick(dot)mail(dog)gmail(dot)com [2010-09-09 18:28:13]

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.

[#12] jonb at wobblymusic dot com [2009-09-06 12:21:09]

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; } ?>

[#13] MitMacher [2009-08-07 14:57:02]

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); ?>

[#14] pablo at compuar dot com [2008-12-30 15:46:59]

If you want to send a very long value over URL, you might consider using base64_encode, and discover that IE6 only supports 2000 or so chars.

So, Using a little bit of magic you can do this and be happy:

<?php $string = 'Blah'; $encoded = strtr(base64_encode(addslashes(gzcompress(serialize($string),9))), '+/=', '-_,'); $string= unserialize(gzuncompress(stripslashes(base64_decode(strtr($encoded, '-_,', '+/='))))); ?>

[#15] gglockner AT NOSPAMdwaffler DOT com [2008-09-19 20:21:24]

I omitted the strtr functions in my examples. Here are corrected functions:

<?php function encode($x) { return strtr(base64_encode(substr($_SESSION['Cksum'],rand(0,28),4) . $x), '+/=', '-_~'); } function decode($x) { $y = base64_decode(strtr($x, '-_~', '+/=')); if (strpos($_SESSION['Cksum'],substr($y,0,4)) === false) return false; return substr($y,4-strlen($y)); } ?>

[#16] gglockner AT NOSPAMdwaffler DOT com [2008-09-19 06:35:56]

I have another solution that is simple and elegant. Create a pseudorandom string of characters. Then, each time you want to obfuscate your key, append a random substring from the pseudorandom string and use base64 encoding. When you want to de-obfuscate, convert back from base64. If the prefix is not in your pseudorandom source, then the value is forged. Otherwise, strip the prefix and recover your original key.

The advantages are that the string will look different even for the same key, and encoding and decoding should be extremely fast.

Here's an example:

<?php // Call makeCksum once upon landing on the homepage function makeCksum() { $str = ""; for ($i=0;$i<32;++$i) $str .= chr(rand(32,126)); $_SESSION['Cksum'] = $str; } function encode($x) { return base64_encode(substr($_SESSION['Cksum'],rand(0,28),4) . $x); } function decode($x) { $y = base64_decode($x); if (strpos($_SESSION['Cksum'],substr($y,0,4)) === false) return false; return substr($y,4-strlen($y)); } ?>

[#17] Andi [2008-03-31 13:54:18]

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.

[#18] Anonymous [2008-02-25 17:11:02]

a note on URI -safe base64.
Simply replacing + = and / with _ - and . doesn't work as the base64_encode function will insert \r \n chars as well which are not URI-safe. So unless we have a base64encode function that does not insert any newline and padddings, the output can never be URI -safe.

referring to the note posted by " web at pkasperski dot com"

- you might as well use $encoded = strtr ( base64_encode ($data), 'ABCDEFG.....', 'aBcDEfG....' ).

this is more efficient. Also, Is simply changing the casing of the letters  more secure? Why don't you try swapping letters around instead

- for your utf8_encode function, the "ord" function returns  a number in the range 0-255. Remember that strings in PHP are actually a sequence of bytes rather than chars. So your utf8 encode func may not work properly. and the line "for ($n = 0; $n < strlen($input); $n++) {" is inefficient, you should assign  a variable $count to  strlen($input) and use it.

referring to
"dlyaza aT yahoo DOT com"

whats the usefulness of encoding your images in a php file??

referring to  "php at ianco dot co dot uk"

- what version of php are you using? Your code works fine for me. I see all the output.

[#19] Tom [2006-12-06 10:20:23]

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.

[#20] eric [at] d512 [dot] com [2006-12-03 19:42:30]

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.

[#21] dlyaza aT yahoo DOT com [2006-10-22 05:57:25]

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///yH5BAHoAwMALAAAA
AARAA0AAAItnIGJxg0B42rsiSvCA/REmXQWhmnih3LUSGaqg35vF
bSXucbSabunjnMohq8CADsA');
case 'folder':
return base64_decode('R0lGODlhEQANAJEDAJmZmf///8zMzP///yH5BAHoAwMALAAAAA
ARAA0AAAIqnI+ZwKwbYgTPtIudlbwLOgCBQJYmCYrn+m3smY5v
Gc+0a7dhjh7ZbygAADsA');
case 'hidden_file':
return base64_decode('R0lGODlhEQANAJEDAMwAAP///5mZmf///yH5BAHoAwMALAAAA
AARAA0AAAItnIGJxg0B42rsiSvCA/REmXQWhmnih3LUSGaqg35vF
bSXucbSabunjnMohq8CADsA');
case 'link':
return base64_decode('R0lGODlhEQANAKIEAJmZmf///wAAAMwAAP///wAAAAAAAAAAA
CH5BAHoAwQALAAAAAARAA0AAAM5SArcrDCCQOuLcIotwgTYUll
NOA0DxXkmhY4shM5zsMUKTY8gNgUvW6cnAaZgxMyIM2zBLCaHlJgAADsA');
case 'smiley':
return base64_decode('R0lGODlhEQANAJECAAAAAP//AP///wAAACH5BAHoAwIALAAAA
AARAA0AAAIslI+pAu2wDAiz0jWD3hqmBzZf1VCleJQch0rkdnppB3
dKZuIygrMRE/oJDwUAOwA=');
case 'arrow':
return base64_decode('R0lGODlhEQANAIABAAAAAP///yH5BAEKAAEALAAAAAARAA0AA
AIdjA9wy6gNQ4pwUmav0yvn+hhJiI3mCJ6otrIkxxQAOw==');
}
}

[#22] php at ianco dot co dot uk [2006-09-22 08:25:20]

I am finding a length restriction with base64_encode (or possibly with echo) in PHP 4.3.9.
This works ok for me:
<?php echo strlen(str_repeat('-', 3273)); // 3273 echo strlen(base64_encode(str_repeat('-', 3273))); // 4364 echo base64_encode(str_repeat('-', 3273)); // LS0t repeated ?>
But change the length to 3274 and the third echo prints nothing.
<?php echo strlen(str_repeat('-', 3274)); // 3274 echo strlen(base64_encode(str_repeat('-', 3274))); // 4368 echo 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.

[#23] peter at mailinator dot com [2006-07-23 14:06:25]

If you want to decode base64 encoded data in Javascript, you can use the tool (Webtoolkit.base64) on this website: http://www.webtoolkit.info/

[#24] greenthumb at 4point-webdesign dot de [2006-04-26 02:57:04]

I had massive problems storing a serialized Object which contained UTF-8 parts and some ascii parts (from the serialization i think) into mysql.

So i used base64_encode to get a clean string which could be safely decoded and unserialized.

this is bulletproof - if you ever have trouble use this.
the runtime is imho no problem.

[#25] dawgeatschikin at hotmail dot com [2006-03-27 20:06:25]

Just a minor tweak of massimo's functions.

<?php $data = str_replace(array('+','/','='),array('-','_','.'),$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 ?>

[#26] massimo dot scamarcia at gmail dot com [2006-03-23 07:23:21]

$data = str_replace(array('+','/','='),array('-','_',),$data); // MIME::Base64::URLSafe implementation

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

[#27] massimo dot scamarcia at gmail dot com [2006-03-23 03:02:14]

[#28] Gabriel Malca [2006-03-17 13:45:25]

If the function doesn't exist, this is a messy but effective way of doing it:

<?php 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)); } ?>

[#29] conradopinto at yahoo dot com dot br [2006-02-09 07:04:18]

There is an error on the example of passing an array through an HTML Form.

In the line:
$array = unserialize(base64_decode($coded_array);

There is a ')' missing. it should be:
$array = unserialize(base64_decode($coded_array));

[#30] virtuall at virtuall dot info [2005-12-06 13:53:14]

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));     }; ?>

[#31] Cristiano Calligaro [2005-08-25 03:05:20]

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 attached
mssql_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!!!)

[#32] juha at kuhazor dot idlegames dot com [2004-06-21 20:29:08]

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; } ?>

[#33] guy at bhaktiandvedanta dot com [2002-10-01 17:00:47]

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:

<?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