Examples with Extensions com.github.zhenwei.core.asn1.x509.Extensions used on opensource projects

Example 51 with Extensions

use of com.github.zhenwei.core.asn1.x509.Extensions in project xipki by xipki.

the class ExtensionsChecker method checkExtensionExtendedKeyUsage.

// method checkExtensionKeyUsage
private void checkExtensionExtendedKeyUsage(StringBuilder failureMsg, byte[] extensionValue, Extensions requestedExtensions, ExtensionControl extControl) {
    Set<String> isUsages = new HashSet<>();
    org.bouncycastle.asn1.x509.ExtendedKeyUsage keyusage = org.bouncycastle.asn1.x509.ExtendedKeyUsage.getInstance(extensionValue);
    KeyPurposeId[] usages = keyusage.getUsages();
    if (usages != null) {
        for (KeyPurposeId usage : usages) {
            isUsages.add(usage.getId());
        }
    }
    Set<String> expectedUsages = new HashSet<>();
    Set<ExtKeyUsageControl> requiredExtKeyusage = getExtKeyusage(true);
    if (requiredExtKeyusage != null) {
        for (ExtKeyUsageControl usage : requiredExtKeyusage) {
            expectedUsages.add(usage.getExtKeyUsage().getId());
        }
    }
    Set<ExtKeyUsageControl> optionalExtKeyusage = getExtKeyusage(false);
    if (requestedExtensions != null && extControl.isRequest() && CollectionUtil.isNonEmpty(optionalExtKeyusage)) {
        Extension extension = requestedExtensions.getExtension(Extension.extendedKeyUsage);
        if (extension != null) {
            org.bouncycastle.asn1.x509.ExtendedKeyUsage reqKeyUsage = org.bouncycastle.asn1.x509.ExtendedKeyUsage.getInstance(extension.getParsedValue());
            for (ExtKeyUsageControl k : optionalExtKeyusage) {
                if (reqKeyUsage.hasKeyPurposeId(KeyPurposeId.getInstance(k.getExtKeyUsage()))) {
                    expectedUsages.add(k.getExtKeyUsage().getId());
                }
            }
        }
    }
    if (CollectionUtil.isEmpty(expectedUsages)) {
        byte[] constantExtValue = getConstantExtensionValue(Extension.keyUsage);
        if (constantExtValue != null) {
            expectedUsages = getExtKeyUsage(constantExtValue);
        }
    }
    Set<String> diffs = strInBnotInA(expectedUsages, isUsages);
    if (CollectionUtil.isNonEmpty(diffs)) {
        failureMsg.append("usages ").append(diffs.toString()).append(" are present but not expected; ");
    }
    diffs = strInBnotInA(isUsages, expectedUsages);
    if (CollectionUtil.isNonEmpty(diffs)) {
        failureMsg.append("usages ").append(diffs.toString()).append(" are absent but are required; ");
    }
}

Example 52 with Extensions

use of com.github.zhenwei.core.asn1.x509.Extensions in project xipki by xipki.

the class ExtensionsChecker method checkExtensions.

// constructor
public List<ValidationIssue> checkExtensions(Certificate cert, X509IssuerInfo issuerInfo, Extensions requestedExtensions, X500Name requestedSubject) {
    ParamUtil.requireNonNull("cert", cert);
    ParamUtil.requireNonNull("issuerInfo", issuerInfo);
    X509Certificate jceCert;
    try {
        jceCert = X509Util.toX509Cert(cert);
    } catch (CertificateException ex) {
        throw new IllegalArgumentException("invalid cert: " + ex.getMessage());
    }
    List<ValidationIssue> result = new LinkedList<>();
    // detect the list of extension types in certificate
    Set<ASN1ObjectIdentifier> presentExtenionTypes = getExensionTypes(cert, issuerInfo, requestedExtensions);
    Extensions extensions = cert.getTBSCertificate().getExtensions();
    ASN1ObjectIdentifier[] oids = extensions.getExtensionOIDs();
    if (oids == null) {
        ValidationIssue issue = new ValidationIssue("X509.EXT.GEN", "extension general");
        result.add(issue);
        issue.setFailureMessage("no extension is present");
        return result;
    }
    List<ASN1ObjectIdentifier> certExtTypes = Arrays.asList(oids);
    for (ASN1ObjectIdentifier extType : presentExtenionTypes) {
        if (!certExtTypes.contains(extType)) {
            ValidationIssue issue = createExtensionIssue(extType);
            result.add(issue);
            issue.setFailureMessage("extension is absent but is required");
        }
    }
    Map<ASN1ObjectIdentifier, ExtensionControl> extensionControls = certProfile.getExtensionControls();
    for (ASN1ObjectIdentifier oid : certExtTypes) {
        ValidationIssue issue = createExtensionIssue(oid);
        result.add(issue);
        if (!presentExtenionTypes.contains(oid)) {
            issue.setFailureMessage("extension is present but is not permitted");
            continue;
        }
        Extension ext = extensions.getExtension(oid);
        StringBuilder failureMsg = new StringBuilder();
        ExtensionControl extControl = extensionControls.get(oid);
        if (extControl.isCritical() != ext.isCritical()) {
            addViolation(failureMsg, "critical", ext.isCritical(), extControl.isCritical());
        }
        byte[] extensionValue = ext.getExtnValue().getOctets();
        try {
            if (Extension.authorityKeyIdentifier.equals(oid)) {
                // AuthorityKeyIdentifier
                checkExtensionIssuerKeyIdentifier(failureMsg, extensionValue, issuerInfo);
            } else if (Extension.subjectKeyIdentifier.equals(oid)) {
                // SubjectKeyIdentifier
                checkExtensionSubjectKeyIdentifier(failureMsg, extensionValue, cert.getSubjectPublicKeyInfo());
            } else if (Extension.keyUsage.equals(oid)) {
                // KeyUsage
                checkExtensionKeyUsage(failureMsg, extensionValue, jceCert.getKeyUsage(), requestedExtensions, extControl);
            } else if (Extension.certificatePolicies.equals(oid)) {
                // CertificatePolicies
                checkExtensionCertificatePolicies(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.policyMappings.equals(oid)) {
                // Policy Mappings
                checkExtensionPolicyMappings(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.subjectAlternativeName.equals(oid)) {
                // SubjectAltName
                checkExtensionSubjectAltName(failureMsg, extensionValue, requestedExtensions, extControl, requestedSubject);
            } else if (Extension.subjectDirectoryAttributes.equals(oid)) {
                // SubjectDirectoryAttributes
                checkExtensionSubjectDirAttrs(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.issuerAlternativeName.equals(oid)) {
                // IssuerAltName
                checkExtensionIssuerAltNames(failureMsg, extensionValue, issuerInfo);
            } else if (Extension.basicConstraints.equals(oid)) {
                // Basic Constraints
                checkExtensionBasicConstraints(failureMsg, extensionValue);
            } else if (Extension.nameConstraints.equals(oid)) {
                // Name Constraints
                checkExtensionNameConstraints(failureMsg, extensionValue, extensions, extControl);
            } else if (Extension.policyConstraints.equals(oid)) {
                // PolicyConstrains
                checkExtensionPolicyConstraints(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.extendedKeyUsage.equals(oid)) {
                // ExtendedKeyUsage
                checkExtensionExtendedKeyUsage(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.cRLDistributionPoints.equals(oid)) {
                // CRL Distribution Points
                checkExtensionCrlDistributionPoints(failureMsg, extensionValue, issuerInfo);
            } else if (Extension.inhibitAnyPolicy.equals(oid)) {
                // Inhibit anyPolicy
                checkExtensionInhibitAnyPolicy(failureMsg, extensionValue, extensions, extControl);
            } else if (Extension.freshestCRL.equals(oid)) {
                // Freshest CRL
                checkExtensionDeltaCrlDistributionPoints(failureMsg, extensionValue, issuerInfo);
            } else if (Extension.authorityInfoAccess.equals(oid)) {
                // Authority Information Access
                checkExtensionAuthorityInfoAccess(failureMsg, extensionValue, issuerInfo);
            } else if (Extension.subjectInfoAccess.equals(oid)) {
                // SubjectInfoAccess
                checkExtensionSubjectInfoAccess(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_extension_admission.equals(oid)) {
                // Admission
                checkExtensionAdmission(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_extension_pkix_ocsp_nocheck.equals(oid)) {
                // ocsp-nocheck
                checkExtensionOcspNocheck(failureMsg, extensionValue);
            } else if (ObjectIdentifiers.id_extension_restriction.equals(oid)) {
                // restriction
                checkExtensionRestriction(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_extension_additionalInformation.equals(oid)) {
                // additionalInformation
                checkExtensionAdditionalInformation(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_extension_validityModel.equals(oid)) {
                // validityModel
                checkExtensionValidityModel(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.privateKeyUsagePeriod.equals(oid)) {
                // privateKeyUsagePeriod
                checkExtensionPrivateKeyUsagePeriod(failureMsg, extensionValue, jceCert.getNotBefore(), jceCert.getNotAfter());
            } else if (Extension.qCStatements.equals(oid)) {
                // qCStatements
                checkExtensionQcStatements(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (Extension.biometricInfo.equals(oid)) {
                // biometricInfo
                checkExtensionBiometricInfo(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_pe_tlsfeature.equals(oid)) {
                // tlsFeature
                checkExtensionTlsFeature(failureMsg, extensionValue, requestedExtensions, extControl);
            } else if (ObjectIdentifiers.id_xipki_ext_authorizationTemplate.equals(oid)) {
                // authorizationTemplate
                checkExtensionAuthorizationTemplate(failureMsg, extensionValue, requestedExtensions, extControl);
            } else {
                byte[] expected;
                if (ObjectIdentifiers.id_smimeCapabilities.equals(oid)) {
                    // SMIMECapabilities
                    expected = smimeCapabilities.getValue();
                } else {
                    expected = getExpectedExtValue(oid, requestedExtensions, extControl);
                }
                if (!Arrays.equals(expected, extensionValue)) {
                    addViolation(failureMsg, "extension valus", hex(extensionValue), (expected == null) ? "not present" : hex(expected));
                }
            }
            if (failureMsg.length() > 0) {
                issue.setFailureMessage(failureMsg.toString());
            }
        } catch (IllegalArgumentException | ClassCastException | ArrayIndexOutOfBoundsException ex) {
            LOG.debug("extension value does not have correct syntax", ex);
            issue.setFailureMessage("extension value does not have correct syntax");
        }
    }
    return result;
}

Example 53 with Extensions

use of com.github.zhenwei.core.asn1.x509.Extensions in project xipki by xipki.

the class IdentifiedX509Certprofile method getExtensions.

/**
 * TODO.
 * @param requestedSubject
 *          Subject requested subject. Must not be {@code null}.
 * @param grantedSubject
 *          Granted subject. Must not be {@code null}.
 * @param requestedExtensions
 *          Extensions requested by the requestor. Could be {@code null}.
 * @param publicKeyInfo
 *          Subject public key. Must not be {@code null}.
 * @param publicCaInfo
 *          CA information. Must not be {@code null}.
 * @param crlSignerCert
 *          CRL signer certificate. Could be {@code null}.
 * @param notBefore
 *          NotBefore. Must not be {@code null}.
 * @param notAfter
 *          NotAfter. Must not be {@code null}.
 * @param caInfo
 *          CA information.
 * @return the extensions of the certificate to be issued.
 */
public ExtensionValues getExtensions(X500Name requestedSubject, X500Name grantedSubject, Extensions requestedExtensions, SubjectPublicKeyInfo publicKeyInfo, PublicCaInfo publicCaInfo, X509Certificate crlSignerCert, Date notBefore, Date notAfter) throws CertprofileException, BadCertTemplateException {
    ParamUtil.requireNonNull("publicKeyInfo", publicKeyInfo);
    ExtensionValues values = new ExtensionValues();
    Map<ASN1ObjectIdentifier, ExtensionControl> controls = new HashMap<>(certprofile.getExtensionControls());
    Set<ASN1ObjectIdentifier> neededExtTypes = new HashSet<>();
    Set<ASN1ObjectIdentifier> wantedExtTypes = new HashSet<>();
    if (requestedExtensions != null) {
        Extension reqExtension = requestedExtensions.getExtension(ObjectIdentifiers.id_xipki_ext_cmpRequestExtensions);
        if (reqExtension != null) {
            ExtensionExistence ee = ExtensionExistence.getInstance(reqExtension.getParsedValue());
            neededExtTypes.addAll(ee.getNeedExtensions());
            wantedExtTypes.addAll(ee.getWantExtensions());
        }
        for (ASN1ObjectIdentifier oid : neededExtTypes) {
            if (wantedExtTypes.contains(oid)) {
                wantedExtTypes.remove(oid);
            }
            if (!controls.containsKey(oid)) {
                throw new BadCertTemplateException("could not add needed extension " + oid.getId());
            }
        }
    }
    // SubjectKeyIdentifier
    ASN1ObjectIdentifier extType = Extension.subjectKeyIdentifier;
    ExtensionControl extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        byte[] encodedSpki = publicKeyInfo.getPublicKeyData().getBytes();
        byte[] skiValue = HashAlgo.SHA1.hash(encodedSpki);
        SubjectKeyIdentifier value = new SubjectKeyIdentifier(skiValue);
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // Authority key identifier
    extType = Extension.authorityKeyIdentifier;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        byte[] ikiValue = publicCaInfo.getSubjectKeyIdentifer();
        AuthorityKeyIdentifier value = null;
        if (ikiValue != null) {
            if (certprofile.includesIssuerAndSerialInAki()) {
                GeneralNames x509CaSubject = new GeneralNames(new GeneralName(publicCaInfo.getX500Subject()));
                value = new AuthorityKeyIdentifier(ikiValue, x509CaSubject, publicCaInfo.getSerialNumber());
            } else {
                value = new AuthorityKeyIdentifier(ikiValue);
            }
        }
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // IssuerAltName
    extType = Extension.issuerAlternativeName;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        GeneralNames value = publicCaInfo.getSubjectAltName();
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // AuthorityInfoAccess
    extType = Extension.authorityInfoAccess;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        AuthorityInfoAccessControl aiaControl = certprofile.getAiaControl();
        List<String> caIssuers = null;
        if (aiaControl == null || aiaControl.isIncludesCaIssuers()) {
            caIssuers = publicCaInfo.getCaCertUris();
        }
        List<String> ocspUris = null;
        if (aiaControl == null || aiaControl.isIncludesOcsp()) {
            ocspUris = publicCaInfo.getOcspUris();
        }
        if (CollectionUtil.isNonEmpty(caIssuers) || CollectionUtil.isNonEmpty(ocspUris)) {
            AuthorityInformationAccess value = CaUtil.createAuthorityInformationAccess(caIssuers, ocspUris);
            addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
        }
    }
    if (controls.containsKey(Extension.cRLDistributionPoints) || controls.containsKey(Extension.freshestCRL)) {
        X500Name crlSignerSubject = (crlSignerCert == null) ? null : X500Name.getInstance(crlSignerCert.getSubjectX500Principal().getEncoded());
        X500Name x500CaPrincipal = publicCaInfo.getX500Subject();
        // CRLDistributionPoints
        extType = Extension.cRLDistributionPoints;
        extControl = controls.remove(extType);
        if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
            if (CollectionUtil.isNonEmpty(publicCaInfo.getCrlUris())) {
                CRLDistPoint value = CaUtil.createCrlDistributionPoints(publicCaInfo.getCrlUris(), x500CaPrincipal, crlSignerSubject);
                addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
            }
        }
        // FreshestCRL
        extType = Extension.freshestCRL;
        extControl = controls.remove(extType);
        if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
            if (CollectionUtil.isNonEmpty(publicCaInfo.getDeltaCrlUris())) {
                CRLDistPoint value = CaUtil.createCrlDistributionPoints(publicCaInfo.getDeltaCrlUris(), x500CaPrincipal, crlSignerSubject);
                addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
            }
        }
    }
    // BasicConstraints
    extType = Extension.basicConstraints;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        BasicConstraints value = CaUtil.createBasicConstraints(certprofile.getCertLevel(), certprofile.getPathLenBasicConstraint());
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // KeyUsage
    extType = Extension.keyUsage;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        Set<KeyUsage> usages = new HashSet<>();
        Set<KeyUsageControl> usageOccs = certprofile.getKeyUsage();
        for (KeyUsageControl k : usageOccs) {
            if (k.isRequired()) {
                usages.add(k.getKeyUsage());
            }
        }
        // the optional KeyUsage will only be set if requested explicitly
        if (requestedExtensions != null && extControl.isRequest()) {
            addRequestedKeyusage(usages, requestedExtensions, usageOccs);
        }
        org.bouncycastle.asn1.x509.KeyUsage value = X509Util.createKeyUsage(usages);
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // ExtendedKeyUsage
    extType = Extension.extendedKeyUsage;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        List<ASN1ObjectIdentifier> usages = new LinkedList<>();
        Set<ExtKeyUsageControl> usageOccs = certprofile.getExtendedKeyUsages();
        for (ExtKeyUsageControl k : usageOccs) {
            if (k.isRequired()) {
                usages.add(k.getExtKeyUsage());
            }
        }
        // the optional ExtKeyUsage will only be set if requested explicitly
        if (requestedExtensions != null && extControl.isRequest()) {
            addRequestedExtKeyusage(usages, requestedExtensions, usageOccs);
        }
        if (extControl.isCritical() && usages.contains(ObjectIdentifiers.id_anyExtendedKeyUsage)) {
            extControl = new ExtensionControl(false, extControl.isRequired(), extControl.isRequest());
        }
        ExtendedKeyUsage value = X509Util.createExtendedUsage(usages);
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // ocsp-nocheck
    extType = ObjectIdentifiers.id_extension_pkix_ocsp_nocheck;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        // the extension ocsp-nocheck will only be set if requested explicitly
        DERNull value = DERNull.INSTANCE;
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // SubjectInfoAccess
    extType = Extension.subjectInfoAccess;
    extControl = controls.remove(extType);
    if (extControl != null && addMe(extType, extControl, neededExtTypes, wantedExtTypes)) {
        ASN1Sequence value = null;
        if (requestedExtensions != null && extControl.isRequest()) {
            value = createSubjectInfoAccess(requestedExtensions, certprofile.getSubjectInfoAccessModes());
        }
        addExtension(values, extType, value, extControl, neededExtTypes, wantedExtTypes);
    }
    // remove extensions that are not required frrom the list
    List<ASN1ObjectIdentifier> listToRm = null;
    for (ASN1ObjectIdentifier extnType : controls.keySet()) {
        ExtensionControl ctrl = controls.get(extnType);
        if (ctrl.isRequired()) {
            continue;
        }
        if (neededExtTypes.contains(extnType) || wantedExtTypes.contains(extnType)) {
            continue;
        }
        if (listToRm == null) {
            listToRm = new LinkedList<>();
        }
        listToRm.add(extnType);
    }
    if (listToRm != null) {
        for (ASN1ObjectIdentifier extnType : listToRm) {
            controls.remove(extnType);
        }
    }
    ExtensionValues subvalues = certprofile.getExtensions(Collections.unmodifiableMap(controls), requestedSubject, grantedSubject, requestedExtensions, notBefore, notAfter, publicCaInfo);
    Set<ASN1ObjectIdentifier> extTypes = new HashSet<>(controls.keySet());
    for (ASN1ObjectIdentifier type : extTypes) {
        extControl = controls.remove(type);
        boolean addMe = addMe(type, extControl, neededExtTypes, wantedExtTypes);
        if (addMe) {
            ExtensionValue value = null;
            if (requestedExtensions != null && extControl.isRequest()) {
                Extension reqExt = requestedExtensions.getExtension(type);
                if (reqExt != null) {
                    value = new ExtensionValue(reqExt.isCritical(), reqExt.getParsedValue());
                }
            }
            if (value == null) {
                value = subvalues.getExtensionValue(type);
            }
            addExtension(values, type, value, extControl, neededExtTypes, wantedExtTypes);
        }
    }
    Set<ASN1ObjectIdentifier> unprocessedExtTypes = new HashSet<>();
    for (ASN1ObjectIdentifier type : controls.keySet()) {
        if (controls.get(type).isRequired()) {
            unprocessedExtTypes.add(type);
        }
    }
    if (CollectionUtil.isNonEmpty(unprocessedExtTypes)) {
        throw new CertprofileException("could not add required extensions " + toString(unprocessedExtTypes));
    }
    if (CollectionUtil.isNonEmpty(neededExtTypes)) {
        throw new BadCertTemplateException("could not add requested extensions " + toString(neededExtTypes));
    }
    return values;
}

Example 54 with Extensions

use of com.github.zhenwei.core.asn1.x509.Extensions in project xipki by xipki.

the class IdentifiedX509Certprofile method addRequestedExtKeyusage.

// method addRequestedKeyusage
private static void addRequestedExtKeyusage(List<ASN1ObjectIdentifier> usages, Extensions requestedExtensions, Set<ExtKeyUsageControl> usageOccs) {
    Extension extension = requestedExtensions.getExtension(Extension.extendedKeyUsage);
    if (extension == null) {
        return;
    }
    ExtendedKeyUsage reqKeyUsage = ExtendedKeyUsage.getInstance(extension.getParsedValue());
    for (ExtKeyUsageControl k : usageOccs) {
        if (k.isRequired()) {
            continue;
        }
        if (reqKeyUsage.hasKeyPurposeId(KeyPurposeId.getInstance(k.getExtKeyUsage()))) {
            usages.add(k.getExtKeyUsage());
        }
    }
}

Example 55 with Extensions

use of com.github.zhenwei.core.asn1.x509.Extensions in project xipki by xipki.

the class CaUtil method getExtensions.

public static Extensions getExtensions(CertificationRequestInfo csr) {
    ParamUtil.requireNonNull("csr", csr);
    ASN1Set attrs = csr.getAttributes();
    for (int i = 0; i < attrs.size(); i++) {
        Attribute attr = Attribute.getInstance(attrs.getObjectAt(i));
        if (PKCSObjectIdentifiers.pkcs_9_at_extensionRequest.equals(attr.getAttrType())) {
            return Extensions.getInstance(attr.getAttributeValues()[0]);
        }
    }
    return null;
}