public void CloseSession()
{
if (this._disposed)
throw new ObjectDisposedException(this.GetType().FullName);
CKR rv = _p11.C_CloseSession(_sessionId);
if (rv != CKR.CKR_OK)
throw new Pkcs11Exception("C_CloseSession", rv);
_sessionId = CK.CK_INVALID_HANDLE;
}