I got it working finally. Here is the complete code of the Timestamper class:
public static class Timestamper
{
[StructLayout(LayoutKind.Sequential)]
struct SIGNER_SUBJECT_INFO
{
public uint cbSize;
public IntPtr pdwIndex;
public uint dwSubjectChoice;
public SubjectChoiceUnion Union1;
[StructLayoutAttribute(LayoutKind.Explicit)]
internal struct SubjectChoiceUnion
{
[FieldOffsetAttribute(0)]
public IntPtr pSignerFileInfo;
[FieldOffsetAttribute(0)]
public IntPtr pSignerBlobInfo;
}
}
[StructLayoutAttribute(LayoutKind.Sequential)]
struct SIGNER_FILE_INFO
{
public uint cbSize;
public IntPtr pwszFileName;
public IntPtr hFile;
}
[DllImport("Mssign32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
private static extern int SignerTimeStampEx2(
uint dwFlags, // DWORD
IntPtr pSubjectInfo, // SIGNER_SUBJECT_INFO
string pwszHttpTimeStamp, // LPCWSTR
IntPtr pszTimeStampAlgorithmOid, // PCSTR
IntPtr psRequest, // PCRYPT_ATTRIBUTES
IntPtr pSipData, // LPVOID
out IntPtr ppSignerContext // SIGNER_CONTEXT
);
public static void TimestampSignedAssembly(string appPath, string tsaServer)
{
if (tsaServer == null) throw new ArgumentNullException("tsaServer");
IntPtr pSubjectInfo = IntPtr.Zero;
try
{
pSubjectInfo = CreateSignerSubjectInfo(appPath);
TimestampSignedAssembly(pSubjectInfo, tsaServer);
}
finally
{
if (pSubjectInfo != IntPtr.Zero)
{
Marshal.DestroyStructure(pSubjectInfo, typeof(SIGNER_SUBJECT_INFO));
}
}
}
private static IntPtr CreateSignerSubjectInfo(string pathToAssembly)
{
SIGNER_SUBJECT_INFO info = new SIGNER_SUBJECT_INFO
{
cbSize = (uint)Marshal.SizeOf(typeof(SIGNER_SUBJECT_INFO)),
pdwIndex = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(uint)))
};
int index = 0;
Marshal.StructureToPtr(index, info.pdwIndex, false);
info.dwSubjectChoice = 0x1; //SIGNER_SUBJECT_FILE
IntPtr assemblyFilePtr = Marshal.StringToHGlobalUni(pathToAssembly);
SIGNER_FILE_INFO fileInfo = new SIGNER_FILE_INFO
{
cbSize = (uint)Marshal.SizeOf(typeof(SIGNER_FILE_INFO)),
pwszFileName = assemblyFilePtr,
hFile = IntPtr.Zero
};
info.Union1 = new SIGNER_SUBJECT_INFO.SubjectChoiceUnion
{
pSignerFileInfo = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(SIGNER_FILE_INFO)))
};
Marshal.StructureToPtr(fileInfo, info.Union1.pSignerFileInfo, false);
IntPtr pSubjectInfo = Marshal.AllocHGlobal(Marshal.SizeOf(info));
Marshal.StructureToPtr(info, pSubjectInfo, false);
return pSubjectInfo;
}
/*
Here CryptoAPI function SignerTimeStampEx2 called.
*/
private static void TimestampSignedAssembly(IntPtr pSubjectInfo, string tsaServer)
{
IntPtr context;
int hResult = SignerTimeStampEx2(
0x2, // SIGNER_TIMESTAMP_RFC3161
pSubjectInfo,
tsaServer,
Marshal.StringToHGlobalAnsi("2.16.840.1.101.3.4.2.1"), // szOID_NIST_sha256 constant, SHA256 hashing algorithm.
IntPtr.Zero,
IntPtr.Zero,
out context
);
if (hResult != 0)
{
throw new Exception(string.Format("Error occured when adding timestamp - Error code: 0x{0:X}", hResult));
}
}
}
Usage example:
Timestamper.TimestampSignedAssembly("Assembly.exe", "http://timestamp.comodoca.com/?td=sha256");