// a particular DEK. The context may be nil.
	GenerateKey(ctx context.Context, keyID string, context Context) (DEK, error)

	// DecryptKey decrypts the ciphertext with the key referenced
	// by the key ID. The context must match the context value
	// used to generate the ciphertext.
	DecryptKey(keyID string, ciphertext []byte, context Context) ([]byte, error)

	// DecryptAll decrypts all ciphertexts with the key referenced