[RESOLVED] help with LsaRetrievePrivateData

[Rodent2008]

Hi,

I am having trouble getting data from LsaRetrievePrivateData.

here is the code

<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True, PreserveSig:=True)> _
    Private Shared Function LsaRetrievePrivateData(ByVal policyHandle As IntPtr, ByRef KeyName As LSA_UNICODE_STRING, ByRef PrivateData As Long) As UInteger
    End Function
 
<DllImport("advapi32.dll", PreserveSig:=True)> _
    Private Shared Function LsaOpenPolicy(ByRef SystemName As LSA_UNICODE_STRING, ByRef ObjectAttributes As LSA_OBJECT_ATTRIBUTES, ByVal DesiredAccess As Int32, ByRef PolicyHandle As IntPtr) As UInt32
    End Function
 
Private Function GetSecret() As String
    Dim lusSecretData As New LSA_UNICODE_STRING()
    Dim PrivateData As Long
    Dim Value As String
 
    Dim LsaPolicyHandle As IntPtr = GetLsaPolicy(LSA_AccessPolicy.POLICY_GET_PRIVATE_INFORMATION)
    Dim result As UInteger = LsaRetrievePrivateData(LsaPolicyHandle, secretName, PrivateData)
    ReleaseLsaPolicy(LsaPolicyHandle)
 
    If result <> 0 Then
        Dim lastError As String = "RetrievePrivateData failed: " & Marshal.GetLastWin32Error & " " & New System.ComponentModel.Win32Exception().Message
        Throw New Exception(lastError)
    End If
 
    lusSecretData = DirectCast(Marshal.PtrToStructure(PrivateData, GetType(LSA_UNICODE_STRING)), LSA_UNICODE_STRING)
    Value = Marshal.PtrToStringUni(lusSecretData.Buffer)

    'lusSecretData = Marshal.PtrToStructure(PrivateData, GetType(LSA_UNICODE_STRING))
    'Value = Marshal.PtrToStringAuto(lusSecretData.Buffer).Substring(0, lusSecretData.Length / 2)

    Return Value
End Function

GetLsaPolicy is a function that returns the LsaPolicyHandle
ReleaseLsaPolicy is a function that closes the LsaPolicyHandle

I have a function that Set the Secret and that all works fine.

What isn't working is the bold sections to get the value back, is there anyone that can guide me in the right direction.

Thanks
Rodney

[chris128]

When you say its "not working" what exactly do you mean? What happens when this code runs? Do you get an exception? If so, what is it? etc etc

[dunfiddlin]

I have a function that Set the Secret and that all works fine.

If you can't retrieve the value how do you know that it worked?

[Rodent2008]

Ok, I have got it working.

Changed

<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True, PreserveSig:=True)> _
    Private Shared Function LsaRetrievePrivateData(ByVal policyHandle As IntPtr, ByRef KeyName As LSA_UNICODE_STRING, ByRef PrivateData As Long) As UInteger
    End Function

To

<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True, PreserveSig:=True)> _
    Private Shared Function LsaRetrievePrivateData(ByVal policyHandle As IntPtr, ByRef KeyName As LSA_UNICODE_STRING, ByRef PrivateData As LSA_UNICODE_STRING) As UInteger
    End Function

and the function looks like this.

    Private Function GetSecret() As String
        Dim lusSecretData As New LSA_UNICODE_STRING()
        Dim PrivateData As IntPtr
        Dim Value As String = ""

        Dim LsaPolicyHandle As IntPtr = GetLsaPolicy(LSA_AccessPolicy.POLICY_GET_PRIVATE_INFORMATION)
        Dim result As UInteger = LsaRetrievePrivateData(LsaPolicyHandle, secretName, PrivateData)
        ReleaseLsaPolicy(LsaPolicyHandle)

        If result <> 0 Then
            Dim lastError As String = "RetrievePrivateData failed: " & Marshal.GetLastWin32Error & " " & New System.ComponentModel.Win32Exception().Message
            Throw New Exception(lastError)
        End If

        lusSecretData = Marshal.PtrToStructure(PrivateData, GetType(LSA_UNICODE_STRING))
        If lusSecretData.Length > 0 Then
            Value = Marshal.PtrToStringAuto(lusSecretData.Buffer).Substring(0, lusSecretData.Length / 2)
        End If
        LsaFreeMemory(PrivateData)

        Return Value
    End Function

This is now resolved.

[chris128]

Ah yeah that would make sense, as that's how MSDN defines it (no idea why you had it as a Long originally really) http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx
Also, MSDN does say "Do not use the LSA private data functions. Instead, use the CryptProtectData and CryptUnprotectData functions."