//
// The same context must be provided when decrypting the
// ciphertext.
func Encrypt(k *kms.KMS, plaintext io.Reader, ctx kms.Context) (io.Reader, error) {
	algorithm := sio.AES_256_GCM
	if !sioutil.NativeAES() {
		algorithm = sio.ChaCha20Poly1305
	}

	key, err := k.GenerateKey(context.Background(), &kms.GenerateKeyRequest{AssociatedData: ctx})
	if err != nil {
		return nil, err
	}