implemented key rotation in RotatingKeyManager

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.oidc.backend/src/main/java/de/srsoftware/oidc/backend/RotatingKeyManager.java

@@ -1,12 +1,16 @@
 /* © SRSoftware 2024 */
 package de.srsoftware.oidc.backend;
 
+import static de.srsoftware.oidc.api.Constants.EXPIRATION;
+import static de.srsoftware.utils.Optionals.nullable;
 import static de.srsoftware.utils.Strings.uuid;
 import static org.jose4j.jws.AlgorithmIdentifiers.RSA_USING_SHA256;
 
 import de.srsoftware.oidc.api.KeyManager;
 import de.srsoftware.oidc.api.KeyStorage;
 import java.io.IOException;
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
 import org.jose4j.jwk.PublicJsonWebKey;
 import org.jose4j.jwk.RsaJwkGenerator;
 import org.jose4j.lang.JoseException;
@@ -21,8 +25,19 @@ public class RotatingKeyManager implements KeyManager {
 
 	@Override
 	public PublicJsonWebKey getKey() throws KeyCreationException, IOException {
-		var list = store.listKeys();
+		for (var keyId : store.listKeys()) {
-		return list.isEmpty() ? createNewKey() : store.load(list.get(0));
+			try {
+				var key     = store.load(keyId);
+				var expired = nullable(key.getOtherParameterValue(EXPIRATION, Long.class)).map(Instant::ofEpochSecond).map(expiration -> expiration.isBefore(Instant.now())).orElse(false);
+				if (expired) {
+					store.drop(keyId);
+				} else
+					return key;
+			} catch (Exception e) {
+				LOG.log(System.Logger.Level.WARNING, "Failed to load key with id {0}", keyId);
+			}
+		}
+		return createNewKey();
 	}
 
 	private PublicJsonWebKey createNewKey() throws KeyCreationException, IOException {
@@ -30,7 +45,9 @@ public class RotatingKeyManager implements KeyManager {
 			var key = RsaJwkGenerator.generateJwk(2048);
 			key.setAlgorithm(RSA_USING_SHA256);
 			key.setKeyId(uuid());
+			key.setOtherParameter(EXPIRATION, Instant.now().plus(1, ChronoUnit.DAYS).getEpochSecond());
 			store.store(key);
+			LOG.log(System.Logger.Level.INFO, "Created new JsonWebKey (Id: {0})", key.getKeyId());
 			return key;
 		} catch (JoseException e) {
 			throw new KeyCreationException(e);

de.srsoftware.oidc.datastore.file/src/main/java/de/srsoftware/oidc/datastore/file/PlaintextKeyStore.java

@@ -1,6 +1,7 @@
 /* © SRSoftware 2024 */
 package de.srsoftware.oidc.datastore.file;
 
+import static java.lang.System.Logger.Level.DEBUG;
 import static java.lang.System.Logger.Level.ERROR;
 import static org.jose4j.jwk.JsonWebKey.OutputControlLevel.INCLUDE_PRIVATE;
 
@@ -26,7 +27,8 @@ public class PlaintextKeyStore implements KeyStorage {
 	}
 	@Override
 	public KeyStorage drop(String keyId) {
-		return null;
+		if (dir.resolve(keyId + ".key").toFile().delete()) LOG.log(DEBUG, "Removed key {0}", keyId);
+		return this;
 	}
 
 	@Override