如何解密从安全桌面获取的身份验证缓冲区

Question

我正在尝试请求用户在安全桌面上输入凭据，但我找不到解密生成的身份验证缓冲区的方法：

凭据来自：

CREDUI_INFO cui = new CREDUI_INFO()
{
    cbSize = (uint)Marshal.SizeOf(typeof(CREDUI_INFO)),
    pszMessageText = "MyMessage",
    pszCaptionText = "MyCaption",
};

bool save = false;
uint authPackage = 0U;
IntPtr authBuffer;
uint authBufferSize;

uint error = CredUIPromptForWindowsCredentials(
                ref cui,
                0U,
                ref authPackage,
                IntPtr.Zero,
                0U,
                out authBuffer,
                out authBufferSize,
                ref save,
                CREDUIWIN_SECURE_PROMPT);

凭据解压缩：

uint userBufferSize = CREDUI_MAX_USERNAME_LENGTH;
uint domainBufferSize = CRED_MAX_STRING_LENGTH;
uint passwordBufferSize = CREDUI_MAX_PASSWORD_LENGTH;
StringBuilder userBuffer = new StringBuilder((int)userBufferSize);
StringBuilder domainBuffer = new String((int)domainBufferSize);
IntPtr passwordBuffer = Marshal.AllocCoTaskMem((int)passwordBufferSize);

bool success = CredUnPackAuthenticationBuffer(
                CRED_PACK_PROTECTED_CREDENTIALS,
                authBuffer, authBufferSize
                userBuffer, ref userBufferSize,
                domainBuffer, ref domainBufferSize,
                passwordBuffer, ref passwordBufferSize);

如果我在CREDUIWIN_SECURE_PROMPT中指定CredUIPromptForWindowsCredentials，如上例所示，CredUnPackAuthenticationBuffer失败并显示ERROR_NOT_CAPABLE。如果我使用CREDUIWIN_GENERIC而不是安全桌面，则会成功。

如何从安全桌面获取此类加密凭据的名称，域名和密码？ 或者，如果不可能，我怎么能一般使用它们？