The ConvertStringSidToSid function converts a string-format SID into a valid, functional SID. You can use this function to retrieve a SID that the ConvertSidToStringSid function converted to string format.

static extern bool ConvertStringSidToSid(

ConvertStringSidToSid(UserObject["SID"].ToString(), out SID_ptr);

Documentation

[ConvertStringSidToSid] on MSDN

2: GetLengthSid

if ( !ConvertStringSidToSid(stringSid, out pSid) )

3: LookupAccountSid

'Input format is the format returned from "ConvertStringSidToSid"

4: SetNamedSecurityInfo

private static extern bool ConvertStringSidToSid(String StringSid, ref IntPtr Sid);

ConvertStringSidToSid(sid.ToString(), ref sidPtr);

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