Base64 conversion of incoming url

[DevAccess]

Hello

I would like to encode incoming url to base 64 if it contains query string ( i.e after ? mark parameter ) as enrollmentnumber"

okay so incoming url would look like this

index.php?enrollmentnumber=1234 if incoming url contains enrollmentnumber then convert anything after question mark ( here it is enrollmentnumber=1234 ) to base 64 encoding.

so output of this would look like this
index.php?32332sAsd122334234231232= ( conversion of enrollmentnumber=1234 to base64)