在新的PHP 7.2 Sodium功能中使用Halite Keys

We have a bunch of data that was encrypted on a PHP 7.1 installation using Halite, and the server was recently updated to 7.2, which libsodium is now part of PHP. We have our key files (public and secret) that consist of 200 characters (showing an old test public key below for demonstration):

31400100d6c01eb5744a3b508b389a2b10e4b554f8f004f8a0afc78beb02f574bbf2d8017563a641bd508e6a3c132e3350bf1bd1bdf402115b2a628dd63cf5cf5dae1fedbe6e4bc2b5e58c372c3bd960fada57741ef204a9a19a767f126af653a60d5be0

They were generated using the following code:

$encryptionKey = KeyFactory::generateEncryptionKey();
KeyFactory::save($encryptionKey, $keyPath . $keyPublic);

We used to encrypt/decrypt like so (of course never on same server):

$webPublicKey = KeyFactory::loadEncryptionPublicKey($keyPath . $keyPublic);
$encrypted = Asymmetric::seal($string,$webPublicKey);

$webSecretKey = KeyFactory::loadEncryptionSecretKey($keyPath . $keySecret);
$decrypted = Asymmetric::unseal($encrypted,$webSecretKey);

How do we use these keys generated in a previous version of libsodium/halite to decrypt our existing data now that we are on PHP 7.2? Trying to use the old keys in the new sodium_ functions in PHP7.2 continually results in errors about key length.

I appreciate any guidance you can provide.

Thanks!