return nil, err
	}
	if stream.NonceSize() != len(metadata.Nonce) {
		return nil, sio.NotAuthentic
	}
	return stream.DecryptReader(ciphertext, metadata.Nonce, nil), nil
}

type encryptedObject struct {
	KeyID  string `json:"keyid"`
	KMSKey []byte `json:"kmskey"`

	Algorithm sio.Algorithm `json:"algorithm"`
	Nonce     []byte        `json:"nonce"`

	if len(value.IV) != IVSize {
		return ErrDecrypt
	}
	if len(value.Nonce) != NonceSize {
		return ErrDecrypt
	}

	switch value.Algorithm {
	case AES256GCM:
		c.Algorithm = kms.AES256
	case CHACHA20POLY1305:
		c.Algorithm = kms.ChaCha20
	default:
		c.Algorithm = 0
	}
	c.ID = value.ID
	c.IV = value.IV
	c.Nonce = value.Nonce
	c.Bytes = value.Bytes
	return nil

	}

	stream, err := sio.AES_256_GCM.Stream(key)
	if err != nil {
		return err
	}
	// Zero nonce, we only use each key once, and 32 bytes is plenty.
	nonce := make([]byte, stream.NonceSize())
	encr := stream.DecryptReader(r, nonce, nil)
	_, err = io.Copy(w, encr)
	if err == nil {
		fmt.Println(okMsg)
	}
	return err

		Ciphertext: `{"aead":"ChaCha20Poly1305","iv":"JbI+vwvYww1lCb5VpkAFuQ==","nonce":"ARjIjJxBSD541Gz8","bytes":"KCbEc2sA0TLvA7aWTWa23AdccVfJMpOxwgG8hm+4PaNrxYfy1xFWZg2gEenVrOgv"}`,
	},
	{
		KeyID:      "my-key",
		Plaintext:  "UnPWsZgVI+T4L9WGNzFlP1PsP1Z6hn2Fx8ISeZfDGnA=",
		Ciphertext: `{"aead":"ChaCha20Poly1305","iv":"r4+yfiVbVIYR0Z2I9Fq+6g==","nonce":"2YpwGwE59GcVraI3","bytes":"k/svMglOU7/Kgwv73heG38NWW575XLcFp3SaxQHDMjJGYyRI3Fiygu2OeutGPXNL"}`,

	}
	var nonce [32]byte
	if _, err := io.ReadFull(random, nonce[:]); err != nil {
		logger.CriticalIf(context.Background(), errOutOfEntropy)
	}

	const Context = "object-encryption-key generation"
	mac := hmac.New(sha256.New, extKey)
	mac.Write([]byte(Context))
	mac.Write(nonce[:])
	mac.Sum(key[:0])
	return key
}

     * @param password
     *            The user's password.
     * @param challenge
     *            The server challenge.
     * @param clientChallenge
     *            The client challenge (nonce).
     * @return the calculated response
     * @throws GeneralSecurityException
     */
    public static byte[] getLMv2Response ( String domain, String user, String password, byte[] challenge, byte[] clientChallenge )

	}
	if c.RedirectURL != "" {
		v.Set("redirect_uri", c.RedirectURL)
	}
	if len(c.Scopes) > 0 {
		v.Set("scope", strings.Join(c.Scopes, " "))
	}
	v.Set("state", state)
	v.Set("nonce", state)
	if strings.Contains(c.Endpoint.AuthURL, "?") {
		buf.WriteByte('&')
	} else {
		buf.WriteByte('?')
	}
	buf.WriteString(v.Encode())
	return buf.String()
}

func main() {

package once

// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v

	// The returned value can no longer be modified once returned.
	// Should be set before calling Get().
	updateFn func(ctx context.Context) (T, error)

	// ttl for a cached value.
	ttl time.Duration

	opts Opts

	// Once can be used to initialize values for lazy initialization.
	// Should be set before calling Get().
	Once sync.Once

	// Managed values.
	val          atomic.Pointer[T]

	"sync"
)

// PipeWriter is similar to io.PipeWriter with wait group
type PipeWriter struct {
	*io.PipeWriter
	once sync.Once
	done func()
}

// CloseWithError close with supplied error the writer end.
func (w *PipeWriter) CloseWithError(err error) error {
	err = w.PipeWriter.CloseWithError(err)
	w.once.Do(func() {
		w.done()
	})
	return err
}

// PipeReader is similar to io.PipeReader with wait group