help with LsaRetrievePrivateData

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Hi,

I am having trouble getting data from LsaRetrievePrivateData.

here is the code

VB

<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

Posted 5-Oct-12 16:56pm

Rodney Smith

Updated 5-Oct-12 18:15pm

Kenneth Haugland

v2

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Rodney Smith · Accepted Answer · 2012-10-08T12:10:00

Ok, I have got it working.

Changed

VB

<dllimport("advapi32.dll",> _
    Private Shared Function LsaRetrievePrivateData(ByVal policyHandle As IntPtr, ByRef KeyName As LSA_UNICODE_STRING, ByRef PrivateData As Long) As UInteger
    End Function

To

VB

<dllimport("advapi32.dll",> _
    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.

VB

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.