Add RevocationState enum

pgpainless-core/src/main/java/org/pgpainless/algorithm/RevocationState.java

@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm;
+
+public enum RevocationState {
+
+    /**
+     * Certificate is not revoked.
+     */
+    notRevoked,
+
+    /**
+     * Certificate is revoked with a soft revocation.
+     */
+    softRevoked,
+
+    /**
+     * Certificate is revoked with a hard revocation.
+     */
+    hardRevoked
+}