implement generic RAT based on OCTET String

Author: Akretsch

README.md

@@ -332,3 +332,24 @@ at `target/site/apidocs/com/siemens/pki/cmpracomponent/main/CmpRaComponent.html`
 # Acknowledgements
 
 This work was partly funded by the German Federal Ministry of Education and Research in the project Quoryptan through grant number **16KIS2033**.
+
+# Support for Remote Attestation in Certificate Signing Requests (CSRs)
+
+This branch supports the internet drafts [Use of Remote Attestation with Certification Signing Requests](https://datatracker.ietf.org/doc/draft-ietf-lamps-csr-attestation/) and [Nonce-based Freshness for Remote Attestation in Certificate Signing Requests (CSRs) for the Certification Management Protocol (CMP) and for Enrollment over Secure Transport (EST) draft-ietf-lamps-attestation-freshness](https://datatracker.ietf.org/doc/draft-ietf-lamps-attestation-freshness/).
+
+## Design
+
+The [RA configuration interface](src/main/java/com/siemens/pki/cmpracomponent/configuration/Configuration.java) allows to
+register an [`com.siemens.pki.cmpracomponent.configuration.RatVerifierAdapter`](src\main\java\com\siemens\pki\cmpracomponent\configuration\RatVerifierAdapter.java)  interface to an external Verifier. This interface is called 
+by a modified [`com.siemens.pki.cmpracomponent.msgprocessing.ServiceImplementation`](src/main/java/com/siemens/pki/cmpracomponent/msgprocessing/ServiceImplementation.java) to obtain a fresh RAT nonce via 
+GENM/GENREP and also by the [`com.siemens.pki.cmpracomponent.msgprocessing.RaDownstream`](src/main/java/com/siemens/pki/cmpracomponent/msgprocessing/RaDownstream.java) to process the subsequent CRMF template. 
+
+The [Client configuration interface](./src/main/java/com/siemens/pki/cmpclientcomponent/configuration/ClientContext.java) allows to register an [`com.siemens.pki.cmpclientcomponent.configuration.ClientAttestationContext`](src/main/java/com/siemens/pki/cmpclientcomponent/configuration/ClientAttestationContext.java) interface to an external Attester.
+
+The package [`com.siemens.pki.verifieradapter.asn1`](src/main/java/com/siemens/pki/verifieradapter/asn1) supports some ASN.1 definitons from [Use of Remote Attestation with Certification Signing Requests](https://datatracker.ietf.org/doc/draft-ietf-lamps-csr-attestation/).
+
+## Test case
+
+The [`com.siemens.pki.cmpclientcomponent.test.TestCrWithRAT`](src/test/java/com/siemens/pki/cmpclientcomponent/test/TestCrWithRAT.java) shows setup and execution of a RAT sequence. 
+
+

src/main/java/com/siemens/pki/cmpclientcomponent/configuration/ClientAttestationContext.java

@@ -0,0 +1,59 @@
+/*
+ *  Copyright (c) 2024 Siemens AG
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+package com.siemens.pki.cmpclientcomponent.configuration;
+
+import com.siemens.pki.verifieradapter.asn1.EvidenceStatement;
+import com.siemens.pki.verifieradapter.asn1.NonceResponseValue.NonceResponse;
+import java.math.BigInteger;
+
+/**
+ * attestation specific configuration
+ *
+ */
+public interface ClientAttestationContext {
+
+    /**
+     * obtain evidence statement from attestation
+     * @param attestationNonce DER encoded {@link NonceResponse}
+     * @return DER encoded {@link EvidenceStatement}
+     */
+    byte[] getEvidenceStatement(byte[] attestationNonce);
+
+    /**
+     * indicates which Verifier to request a nonce from
+     * @return hint or <code>null</code>
+     */
+    default String getNonceRequestHint() {
+        return null;
+    }
+
+    /**
+     * indicates the required length of the requested nonce
+     * @return length or <code>null</code>
+     */
+    default BigInteger getNonceRequestLen() {
+        return null;
+    }
+    /**
+     * indicates which Evidence type to request a nonce for
+     * @return OID formatted string or <code>null</code>
+     */
+    default String getNonceRequestType() {
+        return null;
+    }
+}

src/main/java/com/siemens/pki/cmpclientcomponent/configuration/ClientContext.java

@@ -23,6 +23,16 @@
  */
 public interface ClientContext {
 
+    /**
+     * get remote attestation specific configuration
+     * @return remote attestation specific configuration
+     * or <code>null</code> is no remote attestation shall
+     * be used
+     */
+    default ClientAttestationContext getAttestationContext() {
+        return null;
+    }
+
     /**
      * get enrollment specific configuration
      *

src/main/java/com/siemens/pki/cmpclientcomponent/main/ClientRequestHandler.java

@@ -184,6 +184,21 @@ PKIMessage buildFurtherRequest(final PKIMessage formerResponse, final PKIBody re
                 false);
     }
 
+    PKIMessage buildFurtherRequest(
+            final PKIMessage formerResponse,
+            final PKIBody requestBody,
+            final boolean withImplicitConfirm,
+            final int pvno)
+            throws Exception {
+        final PKIHeader formerResponseHeader = formerResponse.getHeader();
+        return buildRequest(
+                requestBody,
+                formerResponseHeader.getTransactionID(),
+                formerResponseHeader.getSenderNonce(),
+                pvno,
+                withImplicitConfirm);
+    }
+
     PKIMessage buildInitialRequest(final PKIBody requestBody, final boolean withImplicitConfirm) throws Exception {
         return buildInitialRequest(requestBody, withImplicitConfirm, DEFAULT_PVNO);
     }
@@ -297,6 +312,10 @@ PKIBody sendReceiveInitialBody(final PKIBody body, final boolean withImplicitCon
                 .getBody();
     }
 
+    PKIMessage sendReceiveInitialMessage(final PKIBody body) throws Exception {
+        return sendReceiveValidateMessage(buildInitialRequest(body, false), body.getType());
+    }
+
     PKIMessage sendReceiveValidateMessage(PKIMessage request, final int firstRequestType) throws Exception {
         if (nestedValidatorAndProtector != null) {
             request = nestedValidatorAndProtector

src/main/java/com/siemens/pki/cmpclientcomponent/main/CmpClient.java

@@ -20,8 +20,10 @@
 import static com.siemens.pki.cmpracomponent.util.NullUtil.defaultIfNull;
 import static com.siemens.pki.cmpracomponent.util.NullUtil.ifNotNull;
 
+import com.siemens.pki.cmpclientcomponent.configuration.ClientAttestationContext;
 import com.siemens.pki.cmpclientcomponent.configuration.ClientContext;
 import com.siemens.pki.cmpclientcomponent.configuration.EnrollmentContext;
+import com.siemens.pki.cmpclientcomponent.configuration.EnrollmentContext.TemplateExtension;
 import com.siemens.pki.cmpclientcomponent.configuration.RevocationContext;
 import com.siemens.pki.cmpracomponent.configuration.CmpMessageInterface;
 import com.siemens.pki.cmpracomponent.configuration.CrlUpdateRetrievalHandler;
@@ -40,6 +42,13 @@
 import com.siemens.pki.cmpracomponent.protection.ProtectionProvider;
 import com.siemens.pki.cmpracomponent.protection.SignatureBasedProtection;
 import com.siemens.pki.cmpracomponent.util.MessageDumper;
+import com.siemens.pki.verifieradapter.asn1.AttestationObjectIdentifiers;
+import com.siemens.pki.verifieradapter.asn1.EvidenceBundle;
+import com.siemens.pki.verifieradapter.asn1.EvidenceStatement;
+import com.siemens.pki.verifieradapter.asn1.NonceRequestValue;
+import com.siemens.pki.verifieradapter.asn1.NonceRequestValue.NonceRequest;
+import com.siemens.pki.verifieradapter.asn1.NonceResponseValue;
+import com.siemens.pki.verifieradapter.asn1.NonceResponseValue.NonceResponse;
 import java.io.IOException;
 import java.security.KeyPair;
 import java.security.PrivateKey;
@@ -409,6 +418,49 @@ private boolean grantsImplicitConfirm(final PKIMessage msg) {
     public EnrollmentResult invokeEnrollment() {
 
         try {
+            PKIMessage ratNonceResponse = null;
+            EvidenceBundle evidenceBundle = null;
+            final ClientAttestationContext attestationContext = clientContext.getAttestationContext();
+            if (attestationContext != null) {
+                NonceRequest nonceRequest = new NonceRequest(
+                        attestationContext.getNonceRequestLen(),
+                        attestationContext.getNonceRequestType(),
+                        attestationContext.getNonceRequestHint());
+                NonceRequestValue nonceRequestValue = new NonceRequestValue(new NonceRequest[] {nonceRequest});
+                ratNonceResponse = requestHandler.sendReceiveInitialMessage(new PKIBody(
+                        PKIBody.TYPE_GEN_MSG,
+                        new GenMsgContent(new InfoTypeAndValue(
+                                AttestationObjectIdentifiers.id_it_NonceRequest, nonceRequestValue))));
+                final PKIBody ratNonceResponseBody = ratNonceResponse.getBody();
+                if (ratNonceResponseBody.getType() != PKIBody.TYPE_GEN_REP) {
+                    logUnexpectedResponse(ratNonceResponseBody);
+                    return null;
+                }
+
+                final GenRepContent content = (GenRepContent) ratNonceResponseBody.getContent();
+                final InfoTypeAndValue[] itav = content.toInfoTypeAndValueArray();
+                if (itav != null) {
+                    for (final InfoTypeAndValue aktitav : itav) {
+                        if (AttestationObjectIdentifiers.id_it_NonceResponse.equals(aktitav.getInfoType())) {
+                            final ASN1Encodable infoValue = aktitav.getInfoValue();
+                            if (infoValue == null) {
+                                LOGGER.error("no RAT nonce received");
+                                return null;
+                            }
+                            final NonceResponseValue ratNonce = NonceResponseValue.getInstance(infoValue);
+                            NonceResponse[] nonceResponses = ratNonce.getNonceResponse();
+                            EvidenceStatement[] evidenceStatements = new EvidenceStatement[nonceResponses.length];
+                            for (int i = 0; i < nonceResponses.length; i++) {
+                                NonceResponse aktnonce = nonceResponses[i];
+                                evidenceStatements[i] = EvidenceStatement.getInstance(
+                                        attestationContext.getEvidenceStatement(aktnonce.getEncoded()));
+                            }
+                            evidenceBundle = new EvidenceBundle(evidenceStatements, null);
+                            break;
+                        }
+                    }
+                }
+            }
             final EnrollmentContext enrollmentContext = clientContext.getEnrollmentContext();
             final KeyPair certificateKeypair = enrollmentContext.getCertificateKeypair();
 
@@ -459,16 +511,25 @@ public EnrollmentResult invokeEnrollment() {
                 case PKIBody.TYPE_CERT_REQ:
                 case PKIBody.TYPE_INIT_REQ: {
                     final String subject = enrollmentContext.getSubject();
-                    final Extension[] arrayOfExtensions =
-                            ifNotNull(enrollmentContext.getExtensions(), exts -> exts.stream()
-                                    .map(ext -> new Extension(
-                                            new ASN1ObjectIdentifier(ext.getId()), ext.isCritical(), ext.getValue()))
-                                    .toArray(Extension[]::new));
-                    final Extensions extensions = ifNotNull(arrayOfExtensions, Extensions::new);
+                    final List<Extension> extensions = new ArrayList<>();
+
+                    final List<TemplateExtension> extensionsFromConfig = enrollmentContext.getExtensions();
+                    if (extensionsFromConfig != null) {
+                        extensionsFromConfig.stream()
+                                .map(ext -> new Extension(
+                                        new ASN1ObjectIdentifier(ext.getId()), ext.isCritical(), ext.getValue()))
+                                .forEach(extensions::add);
+                    }
+                    if (evidenceBundle != null) {
+                        extensions.add(
+                                Extension.create(AttestationObjectIdentifiers.id_aa_evidence, false, evidenceBundle));
+                    }
                     final CertTemplateBuilder ctb = new CertTemplateBuilder()
                             .setSubject(ifNotNull(subject, X500Name::new))
-                            .setPublicKey(enrolledPublicKeyInfo)
-                            .setExtensions(extensions);
+                            .setPublicKey(enrolledPublicKeyInfo);
+                    if (!extensions.isEmpty()) {
+                        ctb.setExtensions(new Extensions(extensions.toArray(new Extension[extensions.size()])));
+                    }
                     requestBody = PkiMessageGenerator.generateIrCrKurBody(
                             enrollmentType, ctb.build(), null, enrolledPrivateKey);
                     pvno = enrolledPrivateKey == null ? PKIHeader.CMP_2021 : PKIHeader.CMP_2000;
@@ -478,9 +539,13 @@ public EnrollmentResult invokeEnrollment() {
                     LOGGER.error("EnrollmentType must be 0(ir), 2(cr), 7(kur) or 4(p10cr)");
                     return null;
             }
-            final PKIMessage responseMessage = requestHandler.sendReceiveValidateMessage(
-                    requestHandler.buildInitialRequest(requestBody, enrollmentContext.getRequestImplictConfirm(), pvno),
-                    enrollmentType);
+            final PKIMessage enrollmentRequestMessage = ratNonceResponse == null
+                    ? requestHandler.buildInitialRequest(
+                            requestBody, enrollmentContext.getRequestImplictConfirm(), pvno)
+                    : requestHandler.buildFurtherRequest(
+                            ratNonceResponse, requestBody, enrollmentContext.getRequestImplictConfirm(), pvno);
+            final PKIMessage responseMessage =
+                    requestHandler.sendReceiveValidateMessage(enrollmentRequestMessage, enrollmentType);
             final PKIBody responseBody = responseMessage.getBody();
             final int responseMessageType = responseBody.getType();
             if (enrollmentType == PKIBody.TYPE_P10_CERT_REQ) {

src/main/java/com/siemens/pki/cmpracomponent/configuration/Configuration.java

@@ -89,6 +89,19 @@ public interface Configuration {
      */
     InventoryInterface getInventory(String certProfile, int bodyType);
 
+    /**
+     * optionally access function to external remote attestation verify adapter
+     *
+     * @param certProfile certificate profile extracted from the CMP request header
+     *                    generalInfo field or <code>null</code> if no certificate
+     *                    profile was specified
+     * @param bodyType    request/response PKI Message Body type
+     * @return external RatVerifierAdapter or <code>null</code>
+     */
+    default RatVerifierAdapter getVerifierAdapter(String certProfile, int bodyType) {
+        return null;
+    }
+
     /**
      * provide a persistence implementation
      *

src/main/java/com/siemens/pki/cmpracomponent/configuration/GetFreshRatNonceHandler.java

@@ -0,0 +1,27 @@
+/*
+ *  Copyright (c) 2023 Siemens AG
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+package com.siemens.pki.cmpracomponent.configuration;
+
+/**
+ * support message handler supporting Remote Attestation Procedures nonce genm
+ * requests, see https://datatracker.ietf.org/doc/draft-ietf-rats-reference-interaction-models/ ,
+ * and https://github.com/veraison/docs/blob/main/api/challenge-response/README.md
+ */
+public interface GetFreshRatNonceHandler extends SupportMessageHandlerInterface {
+    // up to now only a placeholder
+}

src/main/java/com/siemens/pki/cmpracomponent/configuration/RatVerifierAdapter.java

@@ -0,0 +1,84 @@
+/*
+ *  Copyright (c) 2025 Siemens AG
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+package com.siemens.pki.cmpracomponent.configuration;
+
+import com.siemens.pki.verifieradapter.asn1.AttestationResult;
+import com.siemens.pki.verifieradapter.asn1.EvidenceStatement;
+import java.math.BigInteger;
+
+/**
+ * adapter to remote attestation verfier
+ */
+public interface RatVerifierAdapter {
+
+    /**
+     * turn evidence into verification result
+     * @param transactionId current CMP transactionId, used to map related calls to getFreshRatNonce and processRatVerification
+     * @param evidence evidence provided by EE as DER encoded {@link EvidenceStatement}
+     * @return verification result as DER  encoded {@link AttestationResult}
+     * @throws Exception in case of error
+     */
+    byte[] processRatVerification(byte[] transactionId, byte[] evidence) throws Exception;
+
+    interface NonceResponseRet {
+
+        /**
+         * retuns the nonce of length len provided by the Verifier indicated with hint
+         * @return nonce
+         */
+        byte[] getNonce();
+
+        /**
+         * indicates how long in seconds the Verifier considers the nonce valid
+         * @return time in seconds or <code>null</code>
+         */
+        default Integer getExpiry() {
+            return null;
+        }
+
+        /**
+         * indicates which Verifier to request a nonce from
+         * @return hint or <code>null</code>
+         */
+        default String getHint() {
+            return null;
+        }
+
+        /**
+         * indicates which Evidence type to request a nonce for
+         * @return OID or <code>null</code>
+         */
+        default String getType() {
+            return null;
+        }
+        ;
+    }
+
+    /**
+     * Generate nonce
+     * @param transactionId current CMP transactionId, used to map related calls to getFreshRatNonce and processRatVerification
+     * @param len the required length of the requested nonce, maybe <code>null</code>
+     * @param type indicates which Evidence type to request a nonce for, OID as string or <code>null</code>
+     * @param hint indicates which Verifier to request a nonce from, maybe <code>null</code>
+     * @param encodedNonceRequest encoded NonceRequest containing len, type and hint
+     * @return fresh BER encoded NonceResponse
+     */
+    NonceResponseRet generateNonce(
+            byte[] transactionId, BigInteger len, String type, String hint, byte[] encodedNonceRequest)
+            throws Exception;
+}