Exceptions ========== .. currentmodule:: cryptography.exceptions .. class:: UnsupportedAlgorithm Raised when the requested algorithm, or combination of algorithms is not supported. .. class:: AlreadyFinalized This is raised when a context is used after being finalized. .. class:: InvalidSignature This is raised when signature verification fails. This can occur with HMAC or asymmetric key signature validation. .. class:: NotYetFinalized This is raised when the AEAD tag property is accessed on a context before it is finalized. .. class:: AlreadyUpdated This is raised when additional data is added to a context after update has already been called. .. class:: InvalidKey This is raised when the verify method of a key derivation function's computed key does not match the expected key.