Add sample for self-signed certificate Mutual-TLS client authentication method

Issue gh-1559

samples/demo-client/src/main/java/sample/web/JwkSetController.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2020-2024 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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.
+ */
+package sample.web;
+
+import java.security.KeyStore;
+import java.security.cert.Certificate;
+import java.security.interfaces.RSAPublicKey;
+import java.util.Collections;
+import java.util.Map;
+import java.util.UUID;
+
+import com.nimbusds.jose.jwk.JWKSet;
+import com.nimbusds.jose.jwk.KeyUse;
+import com.nimbusds.jose.jwk.RSAKey;
+import com.nimbusds.jose.util.Base64;
+
+import org.springframework.boot.ssl.SslBundle;
+import org.springframework.boot.ssl.SslBundles;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * @author Joe Grandja
+ * @since 1.3
+ */
+@RestController
+public class JwkSetController {
+	private final JWKSet jwkSet;
+
+	public JwkSetController(SslBundles sslBundles) throws Exception {
+		this.jwkSet = initJwkSet(sslBundles);
+	}
+
+	@GetMapping("/jwks")
+	public Map<String, Object> getJwkSet() {
+		return this.jwkSet.toJSONObject();
+	}
+
+	private static JWKSet initJwkSet(SslBundles sslBundles) throws Exception {
+		SslBundle sslBundle = sslBundles.getBundle("self-signed-demo-client");
+		KeyStore keyStore = sslBundle.getStores().getKeyStore();
+		String alias = sslBundle.getKey().getAlias();
+
+		Certificate certificate = keyStore.getCertificate(alias);
+
+		RSAKey rsaKey = new RSAKey.Builder((RSAPublicKey) certificate.getPublicKey())
+				.keyUse(KeyUse.SIGNATURE)
+				.keyID(UUID.randomUUID().toString())
+				.x509CertChain(Collections.singletonList(Base64.encode(certificate.getEncoded())))
+				.build();
+
+		return new JWKSet(rsaKey);
+	}
+
+}