protected virtual PkixCertPathBuilderResult Build(
X509Certificate tbvCert,
PkixBuilderParameters pkixParams,
IList tbvPath)
{
// If tbvCert is readily present in tbvPath, it indicates having run
// into a cycle in the PKI graph.
if (tbvPath.Contains(tbvCert))
{
return(null);
}
// step out, the certificate is not allowed to appear in a certification
// chain.
if (pkixParams.GetExcludedCerts().Contains(tbvCert))
{
return(null);
}
// test if certificate path exceeds maximum length
if (pkixParams.MaxPathLength != -1)
{
if (tbvPath.Count - 1 > pkixParams.MaxPathLength)
{
return(null);
}
}
tbvPath.Add(tbvCert);
// X509CertificateParser certParser = new X509CertificateParser();
PkixCertPathBuilderResult builderResult = null;
PkixCertPathValidator validator = new PkixCertPathValidator();
try
{
// check whether the issuer of <tbvCert> is a TrustAnchor
if (PkixCertPathValidatorUtilities.FindTrustAnchor(tbvCert, pkixParams.GetTrustAnchors()) != null)
{
// exception message from possibly later tried certification
// chains
PkixCertPath certPath = null;
try
{
certPath = new PkixCertPath(tbvPath);
}
catch (Exception e)
{
throw new Exception(
"Certification path could not be constructed from certificate list.",
e);
}
PkixCertPathValidatorResult result = null;
try
{
result = (PkixCertPathValidatorResult)validator.Validate(
certPath, pkixParams);
}
catch (Exception e)
{
throw new Exception(
"Certification path could not be validated.", e);
}
return(new PkixCertPathBuilderResult(certPath, result.TrustAnchor,
result.PolicyTree, result.SubjectPublicKey));
}
else
{
// add additional X.509 stores from locations in certificate
try
{
PkixCertPathValidatorUtilities.AddAdditionalStoresFromAltNames(
tbvCert, pkixParams);
}
catch (CertificateParsingException e)
{
throw new Exception(
"No additiontal X.509 stores can be added from certificate locations.",
e);
}
// try to get the issuer certificate from one of the stores
HashSet issuers = new HashSet();
try
{
issuers.AddAll(PkixCertPathValidatorUtilities.FindIssuerCerts(tbvCert, pkixParams));
}
catch (Exception e)
{
throw new Exception(
"Cannot find issuer certificate for certificate in certification path.",
e);
}
if (issuers.IsEmpty)
{
throw new Exception("No issuer certificate for certificate in certification path found.");
}
foreach (X509Certificate issuer in issuers)
{
builderResult = Build(issuer, pkixParams, tbvPath);
if (builderResult != null)
{
break;
}
}
}
}
catch (Exception e)
{
certPathException = e;
}
if (builderResult == null)
{
tbvPath.Remove(tbvCert);
}
return(builderResult);
}
/**
* Build and validate a CertPath using the given parameter.
*
* @param params PKIXBuilderParameters object containing all information to
* build the CertPath
*/
public virtual PkixCertPathBuilderResult Build(
PkixBuilderParameters pkixParams)
{
// search target certificates
IX509Selector certSelect = pkixParams.GetTargetConstraints();
if (!(certSelect is X509AttrCertStoreSelector))
{
throw new PkixCertPathBuilderException(
"TargetConstraints must be an instance of "
+ typeof(X509AttrCertStoreSelector).FullName
+ " for "
+ typeof(PkixAttrCertPathBuilder).FullName + " class.");
}
ICollection targets;
try
{
targets = PkixCertPathValidatorUtilities.FindCertificates(
(X509AttrCertStoreSelector)certSelect, pkixParams.GetStores());
}
catch (Exception e)
{
throw new PkixCertPathBuilderException("Error finding target attribute certificate.", e);
}
if (targets.Count == 0)
{
throw new PkixCertPathBuilderException(
"No attribute certificate found matching targetContraints.");
}
PkixCertPathBuilderResult result = null;
// check all potential target certificates
foreach (IX509AttributeCertificate cert in targets)
{
X509CertStoreSelector selector = new X509CertStoreSelector();
X509Name[] principals = cert.Issuer.GetPrincipals();
ISet issuers = new HashSet();
for (int i = 0; i < principals.Length; i++)
{
try
{
selector.Subject = principals[i];
issuers.AddAll(PkixCertPathValidatorUtilities.FindCertificates(selector, pkixParams.GetStores()));
}
catch (Exception e)
{
throw new PkixCertPathBuilderException(
"Public key certificate for attribute certificate cannot be searched.",
e);
}
}
if (issuers.IsEmpty)
{
throw new PkixCertPathBuilderException("Public key certificate for attribute certificate cannot be found.");
}
IList certPathList = Platform.CreateArrayList();
foreach (X509Certificate issuer in issuers)
{
result = Build(cert, issuer, pkixParams, certPathList);
if (result != null)
{
break;
}
}
if (result != null)
{
break;
}
}
if (result == null && certPathException != null)
{
throw new PkixCertPathBuilderException(
"Possible certificate chain could not be validated.",
certPathException);
}
if (result == null && certPathException == null)
{
throw new PkixCertPathBuilderException(
"Unable to find certificate chain.");
}
return(result);
}
