/// <summary>
/// Gets PKCS#7 signature object of signed file. If file is not signed using authenticode signature, the method return null.
/// </summary>
/// <param name="fileInfo">An instance of file object.</param>
/// <returns>Detached signature object.</returns>
public static DefaultSignedPkcs7 GetSignatureObject(this FileInfo fileInfo)
{
if (!fileInfo.Exists)
{
return(null);
}
const Int32 CMSG_ENCODED_MESSAGE = 29;
const Int32 dwExpectedContentTypeFlags = Wincrypt.CERT_QUERY_CONTENT_FLAG_PKCS7_SIGNED
| Wincrypt.CERT_QUERY_CONTENT_FLAG_PKCS7_SIGNED_EMBED;
if (!Crypt32.CryptQueryObject(
Wincrypt.CERT_QUERY_OBJECT_FILE,
fileInfo.FullName,
dwExpectedContentTypeFlags,
Wincrypt.CERT_QUERY_FORMAT_FLAG_ALL,
0,
out Int32 _,
out Int32 pdwContentType,
out Int32 _,
out IntPtr phCertStore,
out IntPtr phMsg,
out IntPtr ppvContext
))
{
return(null);
}
if (!Crypt32.CryptMsgGetParam(phMsg, CMSG_ENCODED_MESSAGE, 0, null, out Int32 pcbData))
{
return(null);
}
var pvData = new Byte[pcbData];
Crypt32.CryptMsgGetParam(phMsg, CMSG_ENCODED_MESSAGE, 0, pvData, out pcbData);
Crypt32.CryptMsgClose(phMsg);
Crypt32.CertCloseStore(phCertStore, 0);
switch (pdwContentType)
{
case Wincrypt.CERT_QUERY_CONTENT_FLAG_CERT:
case Wincrypt.CERT_QUERY_CONTENT_FLAG_SERIALIZED_CERT:
Crypt32.CertFreeCertificateContext(ppvContext);
break;
}
return(new DefaultSignedPkcs7(pvData));
}
protected override bool ReleaseHandle()
{
return(Crypt32.CryptMsgClose(handle));
}
