func (a *AuthRequest) unsignedBuffer() *buffer.Buffer {
b := buffer.Buffer{}
b.AddBuffer(a.ChallengeBuffer)
b.AddString(a.RequestUrl)
b.AddString(a.Username)
b.AddString(a.ServiceName)
b.AddString(a.AuthMethod)
b.AddString(a.SigningAlgorithm)
// b.AddVarBytes(publicKeyBytes(a.PublicKey))
panic("todo")
return &b
}