PHP Base85

A pure PHP extension to encode and decode data with base85.

Usage:

require("/path/to/base85.class.php");

$encoded = base85::encode('Base85 is pretty cool');
$decoded = base85::decode(':e4D*;K$&\Er');

print "Encoded: $encoded\n";
print "Decoded: $decoded\n";

Should output:

Encoded: 6=FqH3&MgmF!,FBATW$>+Cf>.C]
Decoded: PHP Rocks

Note: There is a PHP extension written in C also named php-base85. That library is most likely faster, but may be harder to install (requires the ability to load extensions).

Note on 32bit:

Base85 requires doing math on numbers larger than 2^31. 32bit PHP cannot do math on an integer this large. On 32bit systems we use the gmp extension to work around this limitation. If you are on a 32bit system make sure you have the gmp module enabled in PHP.

All unit tests pass on a 32bit RaspberryPi.