return ErrNotSupported
	}
	return ErrKeyExists
}

// GenerateKey decrypts req.Ciphertext. The key name req.Name must match the key
// name of the secretKey.
//
// The returned DEK is encrypted using AES-GCM and the ciphertext format is compatible
// with KES and MinKMS.
func (s secretKey) GenerateKey(_ context.Context, req *GenerateKeyRequest) (DEK, error) {
	if req.Name != s.keyID {
		return DEK{}, ErrKeyNotFound
	}

	"aes128-ctr", "aes192-ctr", "aes256-ctr",
	"aes128-gcm@openssh.com", gcm256CipherID,
	chacha20Poly1305ID,
	"arcfour256", "arcfour128", "arcfour",
	aes128cbcID,
	tripledescbcID,
}

// preferredCiphers specifies the default preference for ciphers.
// https://cs.opensource.google/go/x/crypto/+/refs/tags/v0.22.0:ssh/common.go;l=37
var preferredCiphers = []string{
	"aes128-gcm@openssh.com", gcm256CipherID,
	chacha20Poly1305ID,