openpgp-php/lib/OpenPgP/SignaturePacket/RevocationKeyPacket.php

<?php

namespace Leenooks\OpenPGP\SignaturePacket;

/**
 * @see http://tools.ietf.org/html/rfc4880#section-5.2.3.15
 */
class RevocationKeyPacket extends Subpacket
{
	protected $tag = 12;
	public $key_algorithm, $fingerprint, $sensitive;

	function body()
	{
		$bytes = '';
		$bytes .= chr(0x80 | ($this->sensitive ? 0x40 : 0x00));
		$bytes .= chr($this->key_algorithm);

		for($i = 0; $i < strlen($this->fingerprint); $i += 2) {
			$bytes .= chr(hexdec($this->fingerprint[$i].$this->fingerprint[$i+1]));
		}

		return $bytes;
	}

	function read()
	{
		// bitfield must have bit 0x80 set, says the spec
		$bitfield = ord($this->read_byte());
		$this->sensitive = $bitfield & 0x40 == 0x40;
		$this->key_algorithm = ord($this->read_byte());

		$this->fingerprint = '';
		while(strlen($this->input) > 0) {
			$this->fingerprint .= sprintf('%02X',ord($this->read_byte()));
		}
	}
}