We are trying to use MimeKit to validate the digitally signed emails(.p7m) signature. When I call signature.Verify(); it is throwing the error message:
{"Failed to verify digital signature: non-empty set
required\r\nParameter name: value"}.
But the same mail was verified successfully by Limilabs.Mail.
I am using the below code to verify the signature.
if (message.Body is MultipartSigned)
{
var signed = (MultipartSigned)message.Body;
foreach (var signature in signed.Verify())
{
try
{
bool valid = signature.Verify();
// If valid is true, then it signifies that the signed content
// has not been modified since this particular signer signed the
// content.
// However, if it is false, then it indicates that the signed
// content has been modified.
}
catch (DigitalSignatureVerifyException)
{
// There was an error verifying the signature.
}
}
}
Can anyone can help me on this why I am getting the error?
The problem here is that MimeKit, by default, uses the DefaultSecureMimeContext backend for S/MIME when the developer hasn't explicitly provided a context for use in the MultipartSigned.Verify() method invocation and also hasn't registered an alternative S/MIME context using CryptographyContext.Register().
Since the DefaultSecureMimeContext starts off with an empty database of S/MIME certificates, it has no trusted anchors (aka Root Certificate Authority certificates) and thus throws the exception you are seeing when it goes to build a certificate chain for the S/MIME signer when verifying the signature.
You can fix this either by importing some Root Certificate Authority certificates (preferably including the one needed in order to build the certificate chain for said signer) -or- by using the WindowsSecureMimeContext:
if (message.Body is MultipartSigned)
{
var signed = (MultipartSigned)message.Body;
using (var ctx = new WindowsSecureMimeContext ()) {
foreach (var signature in signed.Verify(ctx))
{
try
{
bool valid = signature.Verify();
// If valid is true, then it signifies that the signed content
// has not been modified since this particular signer signed the
// content.
// However, if it is false, then it indicates that the signed
// content has been modified.
}
catch (DigitalSignatureVerifyException)
{
// There was an error verifying the signature.
}
}
}
}
Related
I would like to remove a digital signature from a VBA signed excel macro file. However when I look at EPPlus's library I see that the "Signature" property is read-only, and setting the Certificate as null doesn't seem to remove it, only invalidates the signature in the file:
using (ExcelPackage xlPackage = new ExcelPackage(fiNew))
{
xlPackage.Workbook.VbaProject.Signature.Certificate = null;
xlPackage.Save();
}
Calling the dispose method doesn't work either, errors out on the save. Does anybody know how to do this in EPPlus?
Looking at the source just provide a certificate without a private key - see line 137.
internal void Save(ExcelVbaProject proj)
{
if (Certificate == null)
{
return;
}
if (Certificate.HasPrivateKey==false) //No signature. Remove any Signature part
You could for example just use the first certificate in the Trusted Root Certificate Authorities, which have no keys, as long as you are not running on a root certificate authority or somebody improted a PFX by accident... so we filter for that too:
Here is some code to read from the Trusted Root Certificate Authorities store:
using (var store = new X509Store(StoreName.Root, StoreLocation.CurrentUser)) {
store.Open(OpenFlags.ReadOnly);
var someCertWithoutPrivateKey =
store.Certificates
.Cast<X509Certificate2>()
.Where(c => !c.HasPrivateKey)
.FirstOrDefault();
}
I am in need of assistance with signing a string in PHP. We are building a web application which is able to alter profile data on an external website. We want to achieve this without requiring end users to enter our password on our site. The external website therefore created an API which allows us to edit the profile as long we send them email address of the profile signed by a certificate. This allows them to check whether the request came from a trusted source (us).
We tried both native PHP functions and PHPSeclib to sign an email address using a certificate:
$rsa = new RSA();
$rsa->setHash("sha1");
$rsa->setSignatureMode(RSA::SIGNATURE_PKCS1);
$originalkey = file_get_contents('key.ppk');
$rsa->loadKey($originalkey);
echo bin2hex($rsa->sign("test#email.nl"));
// Using native PHP methods
$email = 'test#email.nl';
$signature = '';
$private_key = openssl_pkey_get_private(file_get_contents("key.ppk"));
var_dump(openssl_sign($email, $signature, $private_key, "sha1"));
echo bin2hex($signature);
The signatures are fine because PHP is able to verify the posted signatures. The webservice of the external website does not accept our signatures however. They only allow a signature length of 40 characters whilst a hexidecimal dump of our signature exceeds 1000 characters.
They sent us this C# example to sign a string but we do not have enough C# knowledge to see why the output differs.
string Sign(string username, string thumbprint, string hasher = "SHA1")
{
var store = new
System.Security.Cryptography.X509Certificates.X509Store(System.Security.Cryptography.X509Certificates.StoreLocation.LocalMachine);
store.Open(System.Security.Cryptography.X509Certificates.OpenFlags.OpenExistingOnly |
System.Security.Cryptography.X509Certificates.OpenFlags.ReadOnly);
try
{
foreach (System.Security.Cryptography.X509Certificates.X509Certificate2 certificate in store.Certificates.Find(System.Security.Cryptography.X509Certificates.X509FindType.FindByThumbprint, thumbprint, false))
{
var privateKey = certificate.PrivateKey as System.Security.Cryptography.RSACryptoServiceProvider;
if (privateKey != null)
{
var bytes = privateKey.SignData(Encoding.UTF8.GetBytes(username),
System.Security.Cryptography.HashAlgorithm.Create(hasher));
return string.Join("", bytes.Select(b => b.ToString("x2")));
} else throw new ArgumentException("no private key");
}
}
finally
{
store.Close();
}
return null;
}
Is there anyone who can point us to the right direction?
Thanks in advance!
I've written an ASP.NET Core 2.0 website in C# and have Facebook authentication enabled, so it requires HTTPS. I'm using the native Kestrel web server to host the site and have a listener set to take the PFX certificate per MS' documentation. I can't seem to find a way for Kestrel to recognize the private key after recall from Key Vault. I know it's present, as I wrote two debug statements that indicate it is, in fact present.
This is the function that I'm using to retrieve the secret, which is working.
public static async Task<X509Certificate2> GetKeyVaultCert()
{
X509Certificate2 pfx;
try
{
var kvClient = new KeyVaultClient(new KeyVaultClient.AuthenticationCallback(GetToken));
var secret = await kvClient
.GetSecretAsync("https://macscampvault.vault.azure.net/secrets/letsencrypt").ConfigureAwait(false);
byte[] bytes;
if(secret.ContentType == "application/x-pkcs12")
bytes = Convert.FromBase64String(secret.Value);
else
{
bytes = new byte[0];
Console.WriteLine("secret is not PFX!!");
throw new ArgumentException("This is not a PFX string!!");
}
var password = new SecureString();
var coll = new X509Certificate2Collection();
coll.Import(bytes, null, X509KeyStorageFlags.Exportable);
pfx = coll[0];
// File output added in case I end up needing to write cert to container
// File.WriteAllBytes(Directory.GetCurrentDirectory().ToString() + "/Macs.pfx", bytes);
Console.WriteLine(pfx.HasPrivateKey);
Console.WriteLine(pfx.GetRSAPrivateKey());
}
catch (Exception ex)
{
Console.WriteLine($"There was a problem during the key vault operation\n{ex.Message}");
throw;
}
return pfx;
}
The debug statements after the assignment call pfx = coll[0]; tell me that this private key exists, but when I try to connect to the website using lynx https://localhost I receive the following exception:
System.NotSupportedException: The server mode SSL must use a certificate with the associated private key.
So, how do I use the private key? Here's a gist to the file in question.
I already was helped by How to serialize and deserialize a PFX certificate in Azure Key Vault? but after following it, I got to this state.
In your gist you have the following code:
var keyVaultCert = GetKeyVaultCert().Result ??
throw new ArgumentNullException("GetKeyVaultCert().Result");
pfx = new X509Certificate2(keyVaultCert.RawData);
The second line there removes the private key, because the RawData property just returns the DER encoded X.509 object.
keyVaultCert is already an X509Certificate2 with a private key, you probably want to just use it.
pfx = GetKeyVaultCert().Result ?? throw etc;
I have two x509Certificates installed in my Personal certificate store and wish to retrieve the certificates by Application Policy.
I use the following code to achieve this:
public X509Certificate2 LocateCertificate(Oid oid)
{
var store = new X509Store(Store.My, StoreLocation.CurrentUser);
store.Open(OpenFlags.ReadOnly);
try
{
var certificates = store.Certificates.Find(X509FindType.FindByApplicationPolicy, oid.Value, true);
if(certificates.Count != 1)
{
throw new CryptographicException(string.Format("Expected one certificate, found {0}", certificates.Count);
}
return certificates[0];
}
finally
{
store.Close();
}
}
When both installed X509Certificates have different Extended key Usage values the above method successfully retrieve the correct certificate when provided with a valid OID. However, if one certificate does not have its Extended Key Usage property set it is also returned by the query along with the correct certificate. I want to guard against returning certificates which have:
An incorrect Extended Key Usage value set.
No Extended Key Usage value set.
Any help would be appriciated.
I have posted about this already but no luck since then I have more information I thought I would try again I really hope someone can help. Basically I am reading an XML file and verifying the fact that it has been signed. This code works perfectly when run as an adminitrator but not as network service, the final line resolves to 'true' but when not run as admin doesnt.
NOTE: this is not a problem with reading the XML file this opens fine. The problem is with one of the objects in memory. I 'think' the problem is to do with access control lists on the CryptoKeyRights object.
I have used the following (in the below code) to try and grant everyone access to the CspParams object:
CryptoKeyRights rightsForall = CryptoKeyRights.FullControl;
CryptoKeyAccessRule everyone = new CryptoKeyAccessRule(#"Everyone", CryptoKeyRights.FullControl, AccessControlType.Allow);
cspParams.CryptoKeySecurity = new CryptoKeySecurity();
cspParams.CryptoKeySecurity.AddAccessRule(everyone);
The above code
The code is:
// Verify the signature of an XML file against an asymmetric
// algorithm and return the result.XmlDocument Doc, RSA Key
public static Boolean VerifyLicenceFile(string xmlLicFilePathArg)
{
bool isVerified = false;
try
{
CspParameters cspParams = new CspParameters();
cspParams.KeyContainerName = containerName;
RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(cspParams);
// Create a new XML document.
XmlDocument xmlDoc = new XmlDocument();
// Load an XML file into the XmlDocument object.
xmlDoc.PreserveWhitespace = true;
xmlDoc.Load(xmlLicFilePathArg);
// Check arguments.
if (xmlDoc == null)
throw new ArgumentException("Doc");
if (rsaKey == null)
throw new ArgumentException("Key");
// Create a new SignedXml object and pass it
// the XML document class.
SignedXml signedXml = new SignedXml(xmlDoc);
// Find the "Signature" node and create a new
// XmlNodeList object.
XmlNodeList nodeList = xmlDoc.GetElementsByTagName("Signature");
// Throw an exception if no signature was found.
if (nodeList.Count <= 0)
{
throw new CryptographicException("Verification failed: No Signature was found in the document.");
}
// This example only supports one signature for
// the entire XML document. Throw an exception
// if more than one signature was found.
if (nodeList.Count >= 2)
{
throw new CryptographicException("Verification failed: More that one signature was found for the document.");
}
// Load the first <signature> node.
signedXml.LoadXml((XmlElement)nodeList[0]);
// Check the signature and return the result.
isVerified = signedXml.CheckSignature(rsaKey);
}
catch (Exception ex)
{
}
return isVerified;
}
This sounds more like permissions on the root CA, or the signing cert. So what I'd check is where the certificates in the chain are in the certificate store - if they're in the User store (which would explain it working under Administrator) or the machine store (where they should work for everyone)
The anser for this was not to use the machine to store the keys in...export them and load them independantly...
Is it possible to sign an xml document without having to use KeyContainerName?
This is a problem with the Mandatory Profiles and Temporary profiles.
These profiles are not full users, and do not have their own key stores. You need to use an ephemeral key, or avoid triggering keystore access.
See http://blogs.msdn.com/b/alejacma/archive/2007/10/23/rsacryptoserviceprovider-fails-when-used-with-mandatory-profiles.aspx for details.
You can try setting RSACryptoServiceProvider.UseMachineKeyStore = true.
This might avoid using the user profile's keystore.
If you are using .net 4.0 you can use the new CspParameters.flags CreateEphemeralKey to indicate that the key is independent of the keystore. i.e. it is an in-memory key, not read or saved to the keychain.