public X509Certificate2 FindIssuerCertificate(X509Certificate2 serverX509Certificate2)
{
X509Certificate2 issuerX509Certificate2 = null;
// Find the issuer certificate
X509Chain x509Chain = new X509Chain();
x509Chain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
x509Chain.Build(serverX509Certificate2);
// Iterate though the chain, to validate if it contain a valid root vertificate
X509ChainElementCollection x509ChainElementCollection = x509Chain.ChainElements;
X509ChainElementEnumerator enumerator = x509ChainElementCollection.GetEnumerator();
X509ChainElement x509ChainElement;
X509Certificate2 x509Certificate2 = null;
IDictionary <string, X509Certificate2> map = new Dictionary <string, X509Certificate2>();
// At this point, the certificate is not valid, until a
// it is proved that it has a valid root certificate
while (enumerator.MoveNext())
{
x509ChainElement = enumerator.Current;
x509Certificate2 = x509ChainElement.Certificate;
map.Add(x509Certificate2.Subject, x509Certificate2);
}
if (map.ContainsKey(serverX509Certificate2.Issuer))
{
issuerX509Certificate2 = map[serverX509Certificate2.Issuer];
}
return(issuerX509Certificate2);
}
private void TestOCSP()
{
OcspLookup ocspLookup = new OcspLookup();
X509Store certStore = new X509Store(StoreName.My, StoreLocation.CurrentUser);
certStore.Open(OpenFlags.ReadOnly);
string serial = "4c 05 5a 37";
X509Certificate2Collection collection = certStore.Certificates.Find(X509FindType.FindBySerialNumber, serial, true);
X509Certificate2 cert = null;
if (collection.Count > 0)
{
cert = collection[0];
}
else
{
// the certificate not found
throw new NotImplementedException("The certificate was not found.");
}
X509Chain x509Chain = new X509Chain();
x509Chain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
x509Chain.Build(cert);
// Iterate though the chain, to validate if it contain a valid root vertificate
X509ChainElementCollection x509ChainElementCollection = x509Chain.ChainElements;
X509ChainElementEnumerator enumerator = x509ChainElementCollection.GetEnumerator();
X509ChainElement x509ChainElement;
X509Certificate2 x509Certificate2 = null;
IDictionary <string, X509Certificate2> map = new Dictionary <string, X509Certificate2>();
IList <X509Certificate2> list = new List <X509Certificate2>();
// At this point, the certificate is not valid, until a
// it is proved that it has a valid root certificate
while (enumerator.MoveNext())
{
x509ChainElement = enumerator.Current;
x509Certificate2 = x509ChainElement.Certificate;
list.Add(x509Certificate2);
}
ocspLookup.RevocationResponseOnline(list[0], list[1], "http://ocsp.systemtest8.trust2408.com/responder");
}
private void AddCertificate(X509Certificate2 cert, UnsignedProperties unsignedProperties, bool addCert, IEnumerable <string> ocspServers, IEnumerable <X509Crl> crlList, FirmaXades.Crypto.DigestMethod digestMethod, X509Certificate2[] extraCerts = null)
{
if (addCert)
{
if (CertificateChecked(cert, unsignedProperties))
{
return;
}
string str = Guid.NewGuid().ToString();
Cert cert2 = new Cert();
cert2.IssuerSerial.X509IssuerName = cert.IssuerName.Name;
cert2.IssuerSerial.X509SerialNumber = cert.GetSerialNumberAsDecimalString();
DigestUtil.SetCertDigest(cert.GetRawCertData(), digestMethod, cert2.CertDigest);
cert2.URI = "#Cert" + str;
unsignedProperties.UnsignedSignatureProperties.CompleteCertificateRefs.CertRefs.CertCollection.Add(cert2);
EncapsulatedX509Certificate encapsulatedX509Certificate = new EncapsulatedX509Certificate();
encapsulatedX509Certificate.Id = "Cert" + str;
encapsulatedX509Certificate.PkiData = cert.GetRawCertData();
unsignedProperties.UnsignedSignatureProperties.CertificateValues.EncapsulatedX509CertificateCollection.Add(encapsulatedX509Certificate);
}
X509ChainElementCollection chainElements = CertUtil.GetCertChain(cert, extraCerts).ChainElements;
if (chainElements.Count > 1)
{
X509ChainElementEnumerator enumerator = chainElements.GetEnumerator();
enumerator.MoveNext();
enumerator.MoveNext();
if (!ValidateCertificateByCRL(unsignedProperties, cert, enumerator.Current.Certificate, crlList, digestMethod))
{
X509Certificate2[] array = ValidateCertificateByOCSP(unsignedProperties, cert, enumerator.Current.Certificate, ocspServers, digestMethod);
if (array != null)
{
X509Certificate2 x509Certificate = DetermineStartCert(new List <X509Certificate2>(array));
if (x509Certificate.IssuerName.Name != enumerator.Current.Certificate.SubjectName.Name)
{
X509Chain certChain = CertUtil.GetCertChain(x509Certificate, array);
AddCertificate(certChain.ChainElements[1].Certificate, unsignedProperties, true, ocspServers, crlList, digestMethod, array);
}
}
}
AddCertificate(enumerator.Current.Certificate, unsignedProperties, true, ocspServers, crlList, digestMethod, extraCerts);
}
}
/// <summary>
/// Checks a certificate status in a CRL.
/// </summary>
/// <param name="certificate">The certificate to check</param>
/// <returns>The RevocationResponse object that contains the result</returns>
public RevocationResponse CheckCertificate(X509Certificate2 certificate)
{
/*
* Assumptions:
* - Certificate has an CRL Distribution Points extension value.
* - An HTTP distribution point is present.
*/
// create RevocationResponse and set default values
RevocationResponse response = new RevocationResponse();
response.IsValid = true;
response.NextUpdate = DateTime.MinValue;
if (certificate != null)
{
X509Chain x509Chain = new X509Chain();
x509Chain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
x509Chain.Build(certificate);
// Iterate though the chain, to get the certificate list
X509ChainElementCollection x509ChainElementCollection = x509Chain.ChainElements;
X509ChainElementEnumerator enumerator = x509ChainElementCollection.GetEnumerator();
X509ChainElement x509ChainElement;
X509Certificate2 x509Certificate2 = null;
IDictionary <string, X509Certificate2> map = new Dictionary <string, X509Certificate2>();
IList <X509Certificate2> list = new List <X509Certificate2>();
while (enumerator.MoveNext())
{
x509ChainElement = enumerator.Current;
x509Certificate2 = x509ChainElement.Certificate;
list.Add(x509Certificate2);
}
// now we have a list of the certificate chain
// list[0] -> the function certificate
// list[0 .. lsit.Count] -> middel certificates
// oces1 : none middle certificate exist
// oces2 : one middle certificate exist
// list[list.Count] - > root certificate
// we needed to validate all certificates, except the root certificates
// The question wheather the root certificates is trusted, is validated in MultipleRootX509CertificateValidator
// However - In the case where the root certificate is not installed,
// the chain list will only be 1 length, so no validation is perfored at all.
int index = 0;
//bool chainValid = true;
while (index < (list.Count - 1) && response.IsValid == true)
{
// this.logger.Info("CRL validation the certificate: " + list[index].Subject);
// Retrieve URL distribution points
List <Uri> URLs = this.GetURLs(list[index]);
// The list should only contain one element
// so we are only interesting in the first CRL list
if (URLs.Count > 0)
{
Uri url = URLs[0];
CrlInstance crl = this.GetInstance(url);
try
{
if (!crl.IsRevoked(certificate))
{
// so the certificate is not revoked.
// remember, that the issueing certificate could be revoked.
// So the next update must be the earlist of the all
response.IsValid = true;
if (response.NextUpdate == DateTime.MinValue)
{
response.NextUpdate = crl.getNextUpdate();
}
else if (response.NextUpdate < crl.getNextUpdate())
{
// no new update
// the already registrated 'NextUpdate' is before the crl.getNextUpdate
}
else
{
// new update time
// The already registrated 'NextUpdate', is greater (futher in the future) then crl.getNextUpdate
// so we use the crl.getNextUpdate as next update
response.NextUpdate = crl.getNextUpdate();
}
}
else
{
response.IsValid = false;
}
}
catch (CheckCertificateRevokedUnexpectedException exception)
{
// could not validate the certificate - so i don't trust it
response.Exception = exception;
response.IsValid = false;
}
}
else
{
// url server not identified, so we don't trust this certificate
response.IsValid = false;
}
// increase the index, to check the next certificate
index++;
}
// all the certificate in the chain is now checked.
if (response.IsValid == true)
{
response.RevocationCheckStatus = RevocationCheckStatus.AllChecksPassed;
}
else
{
response.RevocationCheckStatus = RevocationCheckStatus.CertificateRevoked;
}
x509Chain.Reset();
}
else
{
response.IsValid = false;
response.Exception = new CheckCertificateRevokedUnexpectedException(new Exception("Error during CRL lookup. The certificate is null"));//did not have any CRL DistPoints. Certificate: " + certificate));
response.RevocationCheckStatus = RevocationCheckStatus.UnknownIssue;
}
return(response);
}
public bool IsCertificateChildOfRoot(X509Certificate2 certificate, IDictionary <string, X509Certificate2> rootCertificateDirectory)
{
// valid until proved otherwhise
bool isValid = true;
X509Chain x509Chain = this.CreateChain(certificate);
// Modified chain validation of the certificate. We are not interested in Ctl lists
X509ChainStatus status;
int index = 0;
while (isValid && index < x509Chain.ChainStatus.Length)
{
status = x509Chain.ChainStatus[index];
switch (status.Status)
{
case X509ChainStatusFlags.CtlNotSignatureValid:
case X509ChainStatusFlags.CtlNotTimeValid:
case X509ChainStatusFlags.CtlNotValidForUsage:
case X509ChainStatusFlags.NoError:
case X509ChainStatusFlags.OfflineRevocation:
case X509ChainStatusFlags.RevocationStatusUnknown:
{
// so far, still valid
break;
}
case X509ChainStatusFlags.Cyclic:
case X509ChainStatusFlags.HasExcludedNameConstraint:
case X509ChainStatusFlags.HasNotDefinedNameConstraint:
case X509ChainStatusFlags.HasNotPermittedNameConstraint:
case X509ChainStatusFlags.HasNotSupportedNameConstraint:
case X509ChainStatusFlags.InvalidBasicConstraints:
case X509ChainStatusFlags.InvalidExtension:
case X509ChainStatusFlags.InvalidNameConstraints:
case X509ChainStatusFlags.InvalidPolicyConstraints:
case X509ChainStatusFlags.NoIssuanceChainPolicy:
case X509ChainStatusFlags.NotSignatureValid:
case X509ChainStatusFlags.NotTimeNested:
case X509ChainStatusFlags.NotTimeValid:
case X509ChainStatusFlags.NotValidForUsage:
case X509ChainStatusFlags.PartialChain:
case X509ChainStatusFlags.Revoked:
case X509ChainStatusFlags.UntrustedRoot:
{
this.logger.Warn("X509ChainStatusFlags '" + status.Status + "' is not valid, so the certificate '" + certificate.Subject + "' is not valid.");
this.logger.Debug("x509Chain.ChainStatus.Length:" + x509Chain.ChainStatus.Length + ". Index: " + index + ".");
isValid = false;
break;
}
default:
{
this.logger.Warn("The certificate chain.ChainStatus '" + status.Status + "' is not implemented.");
isValid = false;
break;
}
}
index++;
}
if (isValid)
{
// Check if the certificate has the default root certificate as its root
string x509CertificateThumbprint = certificate.Thumbprint.ToLowerInvariant();
if (rootCertificateDirectory.ContainsKey(x509CertificateThumbprint))
{
// certificate is a root certificate - not valid
isValid = false;
}
else
{
// Iterate though the chain, to validate if it contain a valid root vertificate
X509ChainElementCollection x509ChainElementCollection = x509Chain.ChainElements;
X509ChainElementEnumerator enumerator = x509ChainElementCollection.GetEnumerator();
X509ChainElement x509ChainElement;
X509Certificate2 x509Certificate2;
// At this point, the certificate is not valid, until a
// it is proved that it has a valid root certificate
isValid = false;
while (isValid == false && enumerator.MoveNext())
{
x509ChainElement = enumerator.Current;
x509Certificate2 = x509ChainElement.Certificate;
x509CertificateThumbprint = x509Certificate2.Thumbprint.ToLowerInvariant();
if (rootCertificateDirectory.ContainsKey(x509CertificateThumbprint))
{
// The current chain element is in the trusted rootCertificateDirectory
isValid = true;
// now the loop will break, as we have found a trusted root certificate
}
}
this.logger.Debug("Found root certificate in the root certificate list: " + isValid.ToString());
}
}
return(isValid);
}
