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using System;
using System.Collections.Generic;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Security.Certificates;
using Org.BouncyCastle.Utilities.Collections;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.X509.Store;
namespace Org.BouncyCastle.Pkix
{
public class PkixAttrCertPathBuilder
{
/**
* 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
if (!(pkixParams.GetTargetConstraintsAttrCert() is X509AttrCertStoreSelector attrCertSelector))
{
throw new PkixCertPathBuilderException(
"TargetConstraints must be an instance of "
+ typeof(X509AttrCertStoreSelector).FullName
+ " for "
+ typeof(PkixAttrCertPathBuilder).FullName + " class.");
}
HashSet<X509V2AttributeCertificate> targets;
try
{
targets = FindAttributeCertificates(attrCertSelector, pkixParams.GetStoresAttrCert());
}
catch (Exception e)
{
throw new PkixCertPathBuilderException("Error finding target attribute certificate.", e);
}
if (targets.Count == 0)
throw new PkixCertPathBuilderException("No attribute certificate found matching targetConstraints.");
PkixCertPathBuilderResult result = null;
// check all potential target certificates
foreach (var target in targets)
{
X509CertStoreSelector certSelector = new X509CertStoreSelector();
X509Name[] principals = target.Issuer.GetPrincipals();
var issuers = new HashSet<X509Certificate>();
for (int i = 0; i < principals.Length; i++)
{
// TODO Replace loop with a single multiprincipal selector (or don't even use selector)
try
{
certSelector.Subject = principals[i];
CollectionUtilities.CollectMatches(issuers, certSelector, pkixParams.GetStoresCert());
}
catch (Exception e)
{
throw new PkixCertPathBuilderException(
"Public key certificate for attribute certificate cannot be searched.",
e);
}
}
if (issuers.Count < 1)
throw new PkixCertPathBuilderException("Public key certificate for attribute certificate cannot be found.");
var certPathList = new List<X509Certificate>();
foreach (X509Certificate issuer in issuers)
{
result = Build(target, 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;
}
private Exception certPathException;
private PkixCertPathBuilderResult Build(
X509V2AttributeCertificate attrCert,
X509Certificate tbvCert,
PkixBuilderParameters pkixParams,
IList<X509Certificate> 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);
PkixCertPathBuilderResult builderResult = null;
// X509CertificateParser certParser = new X509CertificateParser();
PkixAttrCertPathValidator validator = new PkixAttrCertPathValidator();
try
{
// check whether the issuer of <tbvCert> is a TrustAnchor
if (PkixCertPathValidatorUtilities.IsIssuerTrustAnchor(tbvCert, pkixParams.GetTrustAnchors()))
{
PkixCertPath certPath = new PkixCertPath(tbvPath);
PkixCertPathValidatorResult result;
try
{
result = 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 additional X.509 stores can be added from certificate locations.", e);
}
// try to get the issuer certificate from one of the stores
HashSet<X509Certificate> issuers;
try
{
issuers = PkixCertPathValidatorUtilities.FindIssuerCerts(tbvCert, pkixParams);
}
catch (Exception e)
{
throw new Exception("Cannot find issuer certificate for certificate in certification path.", e);
}
if (issuers.Count < 1)
throw new Exception("No issuer certificate for certificate in certification path found.");
foreach (X509Certificate issuer in issuers)
{
// if untrusted self signed certificate continue
if (PkixCertPathValidatorUtilities.IsSelfIssued(issuer))
continue;
builderResult = Build(attrCert, issuer, pkixParams, tbvPath);
if (builderResult != null)
break;
}
}
}
catch (Exception e)
{
certPathException = new Exception("No valid certification path could be build.", e);
}
if (builderResult == null)
{
tbvPath.Remove(tbvCert);
}
return builderResult;
}
internal static HashSet<X509V2AttributeCertificate> FindAttributeCertificates(
ISelector<X509V2AttributeCertificate> attrCertSelector,
IList<IStore<X509V2AttributeCertificate>> attrCertStores)
{
var attrCerts = new HashSet<X509V2AttributeCertificate>();
foreach (var attrCertStore in attrCertStores)
{
try
{
attrCerts.UnionWith(attrCertStore.EnumerateMatches(attrCertSelector));
}
catch (Exception e)
{
throw new Exception("Problem while picking certificates from X.509 store.", e);
}
}
return attrCerts;
}
}
}
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