validate
Validates the provided Jwk (JSON Web Key) to ensure it conforms to the expected key type and format.
This function checks the following:
The key must be a private key
The key must be a valid Ed25519 key
If any of these checks fail, this function throws an IllegalArgumentException with a descriptive error message.
Parameters
key
The Jwk to validate.
Throws
if the key is not a private key