<?php
// Ciphertext is not sensitive; base64_decode is fine
$sealed_b64 = "oRBXXAV4iQBrxlV4A21Bord8Yo/D8ZlrIIGNyaRCcGBfpz0map52I3xq6l+CST+1NSgQkbV+HiYyFjXWiWiaCGupGf+zl4bgWj/A9Adtem7Jt3h3emrMsLw=";
$sealed = base64_decode($sealed_b64);
// Keypair contains a cryptographic secret; use a timing-safe decoder
$keypair_b64 = "KZkF8wnB7bnC2aXB3lFOqCTc0Z6MllvaQb9ASVG8o2/MsewkuE4u1uaEgTzSakeiYyIW8DGj+02/L3cWIbs9bQ==";
$keypair = sodium_base642bin($keypair_b64, SODIUM_BASE64_VARIANT_ORIGINAL);
$opened = sodium_crypto_box_seal_open($sealed, $keypair);
var_dump($opened);
?>
string(41) "Writing software in PHP can be a delight!"