For basic authentication, username/password uses base64 encoding.

You can check in the soap /rest /http headers once you basic authentication applied.

ex: Soap header:

<soapenv:Header><wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"><wsse:UsernameToken wsu:Id="UsernameToken-3930A8D796899C587114822133705911"><wsse:Username>admin@gcsau</wsse:Username><wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">rules</wsse:Password><wsse:Nonce EncodingType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary">GWntQNIfseSxp5DLH9jbUw==</wsse:Nonce><wsu:Created>2016-12-20T05:56:10.589Z</wsu:Created></wsse:UsernameToken></wsse:Security></soapenv:Header>