New Lines Causes Decoding Failure in MTLS Client Authenticator

[Shenali-SJ]

Description

In mTLS client authenticator, base64 decoding process of the client certificate fails due to presence of new lines. We are currently utilizing base64 class in the java.util package and it is not capable of processing new lines.

Error Message

<ns1:XMLFault xmlns:ns1="http://cxf.apache.org/bindings/xformat"><ns1:faultstring xmlns:ns1="http://cxf.apache.org/bindings/xformat">java.lang.IllegalArgumentException: Illegal base64 character 7b</ns1:faultstring></ns1:XMLFault>

Suggested Fix

Add the logic to remove new lines from the client certificate before the decoding functionality [1].

[1] - https://github.com/wso2-extensions/identity-oauth-addons/blob/4d30af9cdf22aee6c5182372ace5da5a21b88fca/component/org.wso2.carbon.identity.oauth2.token.handler.clientauth.mutualtls/src/main/java/org/wso2/carbon/identity/oauth2/token/handler/clientauth/mutualtls/MutualTLSClientAuthenticator.java#L280