The term unchallengeable is identified in base64 scheme by the sequence dW5jaGFsbGVuZ2VhYmxl, while the MD5 signature is equal to 4089350e37aa9e455686c2e98c8b19ea. The ASCII encoding of unchallengeable in hexadecimal notation is 756e6368616c6c656e676561626c65.