<?php
$dateString = 'Thu, 26 Dec 2013 17:53:05 +0100';
$date = DateTime::createFromFormat(
DateTime::RSS,
$dateString,
new DateTimeZone('UTC')
);
echo $date->getTimestamp().PHP_EOL
.$date->format('r').PHP_EOL;
PD9waHAKCiRkYXRlU3RyaW5nID0gJ1RodSwgMjYgRGVjIDIwMTMgMTc6NTM6MDUgKzAxMDAnOwokZGF0ZSA9IERhdGVUaW1lOjpjcmVhdGVGcm9tRm9ybWF0KAoJRGF0ZVRpbWU6OlJTUywgCgkkZGF0ZVN0cmluZywKCW5ldyBEYXRlVGltZVpvbmUoJ1VUQycpCik7CgplY2hvICRkYXRlLT5nZXRUaW1lc3RhbXAoKS5QSFBfRU9MCiAgICAuJGRhdGUtPmZvcm1hdCgncicpLlBIUF9FT0w7