- str_replace: documentation ( source)
- trim: documentation ( source)
- wordwrap: documentation ( source)
<?php
$start_key='';
$start_key = str_replace('-----BEGIN RSA PUBLIC KEY-----', '', $start_key);
$start_key = trim(str_replace('-----END RSA PUBLIC KEY-----', '', $start_key));
$key = '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' . str_replace("\n", '', $start_key);
$key = "-----BEGIN PUBLIC KEY-----\n" . wordwrap($key, 64, "\n", true) . "\n-----END PUBLIC KEY-----";
echo $key;