/// <summary>
/// Verifies if an OCSP response is genuine
/// If it doesn't verify against the issuer certificate and response's certificates, it may verify
/// using a trusted anchor or cert.
/// </summary>
/// <param name="ocspResp">the OCSP response</param>
/// <param name="issuerCert">the issuer certificate. This certificate is considered trusted and valid by this method.
/// </param>
/// <param name="signDate">sign date</param>
public virtual void IsValidResponse(BasicOcspResp ocspResp, X509Certificate issuerCert, DateTime signDate)
{
// OCSP response might be signed by the issuer certificate or
// the Authorized OCSP responder certificate containing the id-kp-OCSPSigning extended key usage extension
X509Certificate responderCert = null;
// first check if the issuer certificate signed the response
// since it is expected to be the most common case
if (IsSignatureValid(ocspResp, issuerCert))
{
responderCert = issuerCert;
}
// if the issuer certificate didn't sign the ocsp response, look for authorized ocsp responses
// from properties or from certificate chain received with response
if (responderCert == null)
{
if (ocspResp.GetCerts() != null)
{
//look for existence of Authorized OCSP responder inside the cert chain in ocsp response
IEnumerable <X509Certificate> certs = SignUtils.GetCertsFromOcspResponse(ocspResp);
foreach (X509Certificate cert in certs)
{
IList keyPurposes = null;
try {
keyPurposes = cert.GetExtendedKeyUsage();
if ((keyPurposes != null) && keyPurposes.Contains(id_kp_OCSPSigning) && IsSignatureValid(ocspResp, cert))
{
responderCert = cert;
break;
}
}
catch (CertificateParsingException) {
}
}
// Certificate signing the ocsp response is not found in ocsp response's certificate chain received
// and is not signed by the issuer certificate.
if (responderCert == null)
{
throw new VerificationException(issuerCert, "OCSP response could not be verified");
}
// RFC 6960 4.2.2.2. Authorized Responders:
// "Systems relying on OCSP responses MUST recognize a delegation certificate as being issued
// by the CA that issued the certificate in question only if the delegation certificate and the
// certificate being checked for revocation were signed by the same key."
// and
// "This certificate MUST be issued directly by the CA that is identified in the request"
responderCert.Verify(issuerCert.GetPublicKey());
// check if lifetime of certificate is ok
responderCert.CheckValidity(signDate);
// validating ocsp signers certificate
// Check if responders certificate has id-pkix-ocsp-nocheck extension,
// in which case we do not validate (perform revocation check on) ocsp certs for lifetime of certificate
if (responderCert.GetExtensionValue(OcspObjectIdentifiers.PkixOcspNocheck.Id) == null)
{
X509Crl crl;
try {
// TODO should also check for Authority Information Access according to RFC6960 4.2.2.2.1. "Revocation Checking of an Authorized Responder"
// TODO should also respect onlineCheckingAllowed property?
crl = CertificateUtil.GetCRL(responderCert);
}
catch (Exception) {
crl = (X509Crl)null;
}
if (crl != null && crl is X509Crl)
{
CRLVerifier crlVerifier = new CRLVerifier(null, null);
crlVerifier.SetRootStore(rootStore);
crlVerifier.SetOnlineCheckingAllowed(onlineCheckingAllowed);
if (!crlVerifier.Verify((X509Crl)crl, responderCert, issuerCert, signDate))
{
throw new VerificationException(issuerCert, "Authorized OCSP responder certificate was revoked.");
}
}
else
{
ILog logger = LogManager.GetLogger(typeof(iText.Signatures.OCSPVerifier));
logger.Error("Authorized OCSP responder certificate revocation status cannot be checked");
}
}
}
else
{
// TODO throw exception starting from iText version 7.2, but only after OCSPVerifier would allow explicit setting revocation check end points/provide revocation data
// throw new VerificationException(issuerCert, "Authorized OCSP responder certificate revocation status cannot be checked.");
// certificate chain is not present in response received
// try to verify using rootStore according to RFC 6960 2.2. Response:
// "The key used to sign the response MUST belong to one of the following:
// - ...
// - a Trusted Responder whose public key is trusted by the requestor;
// - ..."
if (rootStore != null)
{
try {
foreach (X509Certificate anchor in SignUtils.GetCertificates(rootStore))
{
if (IsSignatureValid(ocspResp, anchor))
{
// certificate from the root store is considered trusted and valid by this method
responderCert = anchor;
break;
}
}
}
catch (Exception) {
responderCert = (X509Certificate)null;
}
}
if (responderCert == null)
{
throw new VerificationException(issuerCert, "OCSP response could not be verified: it does not contain certificate chain and response is not signed by issuer certificate or any from the root store."
);
}
}
}
}
// Certificate Revocation Lists
/// <summary>Gets a CRL from an X509 certificate.</summary>
/// <param name="certificate">the X509Certificate to extract the CRL from</param>
/// <returns>CRL or null if there's no CRL available</returns>
public static X509Crl GetCRL(X509Certificate certificate)
{
return(CertificateUtil.GetCRL(CertificateUtil.GetCRLURL(certificate)));
}
/// <summary>
/// Verifies if an OCSP response is genuine
/// If it doesn't verify against the issuer certificate and response's certificates, it may verify
/// using a trusted anchor or cert.
/// </summary>
/// <param name="ocspResp">the OCSP response</param>
/// <param name="issuerCert">the issuer certificate</param>
/// <exception cref="Org.BouncyCastle.Security.GeneralSecurityException"/>
/// <exception cref="System.IO.IOException"/>
public virtual void IsValidResponse(BasicOcspResp ocspResp, X509Certificate issuerCert)
{
//OCSP response might be signed by the issuer certificate or
//the Authorized OCSP responder certificate containing the id-kp-OCSPSigning extended key usage extension
X509Certificate responderCert = null;
//first check if the issuer certificate signed the response
//since it is expected to be the most common case
if (IsSignatureValid(ocspResp, issuerCert))
{
responderCert = issuerCert;
}
//if the issuer certificate didn't sign the ocsp response, look for authorized ocsp responses
// from properties or from certificate chain received with response
if (responderCert == null)
{
if (ocspResp.GetCerts() != null)
{
//look for existence of Authorized OCSP responder inside the cert chain in ocsp response
IEnumerable <X509Certificate> certs = SignUtils.GetCertsFromOcspResponse(ocspResp);
foreach (X509Certificate cert in certs)
{
IList keyPurposes = null;
try {
keyPurposes = cert.GetExtendedKeyUsage();
if ((keyPurposes != null) && keyPurposes.Contains(id_kp_OCSPSigning) && IsSignatureValid(ocspResp, cert))
{
responderCert = cert;
break;
}
}
catch (CertificateParsingException) {
}
}
// Certificate signing the ocsp response is not found in ocsp response's certificate chain received
// and is not signed by the issuer certificate.
if (responderCert == null)
{
throw new VerificationException(issuerCert, "OCSP response could not be verified");
}
}
else
{
//certificate chain is not present in response received
//try to verify using rootStore
if (rootStore != null)
{
try {
foreach (X509Certificate anchor in SignUtils.GetCertificates(rootStore))
{
if (IsSignatureValid(ocspResp, anchor))
{
responderCert = anchor;
break;
}
}
}
catch (Exception) {
responderCert = (X509Certificate)null;
}
}
// OCSP Response does not contain certificate chain, and response is not signed by any
// of the rootStore or the issuer certificate.
if (responderCert == null)
{
throw new VerificationException(issuerCert, "OCSP response could not be verified");
}
}
}
//check "This certificate MUST be issued directly by the CA that issued the certificate in question".
responderCert.Verify(issuerCert.GetPublicKey());
// validating ocsp signers certificate
// Check if responders certificate has id-pkix-ocsp-nocheck extension,
// in which case we do not validate (perform revocation check on) ocsp certs for lifetime of certificate
if (responderCert.GetExtensionValue(OcspObjectIdentifiers.PkixOcspNocheck.Id) == null)
{
X509Crl crl;
try {
crl = CertificateUtil.GetCRL(responderCert);
}
catch (Exception) {
crl = (X509Crl)null;
}
if (crl != null && crl is X509Crl)
{
CRLVerifier crlVerifier = new CRLVerifier(null, null);
crlVerifier.SetRootStore(rootStore);
crlVerifier.SetOnlineCheckingAllowed(onlineCheckingAllowed);
crlVerifier.Verify((X509Crl)crl, responderCert, issuerCert, DateTimeUtil.GetCurrentUtcTime());
return;
}
}
//check if lifetime of certificate is ok
responderCert.CheckValidity();
}