Kotlin conversion: NotationRegistry

pgpainless-core/src/main/kotlin/org/pgpainless/util/NotationRegistry.kt

@@ -0,0 +1,45 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.util
+
+/**
+ * Registry for known notations.
+ * Since signature verification must reject signatures with critical notations that are not known to the application,
+ * there must be some way to tell PGPainless which notations actually are known.
+ *
+ * To add a notation name, call {@link #addKnownNotation(String)}.
+ */
+class NotationRegistry constructor(notations: Set<String> = setOf()) {
+    private val knownNotations: MutableSet<String>
+
+    init {
+        knownNotations = notations.toMutableSet()
+    }
+
+    /**
+     * Add a known notation name into the registry.
+     * This will cause critical notations with that name to no longer invalidate the signature.
+     *
+     * @param notationName name of the notation
+     */
+    fun addKnownNotation(notationName: String): NotationRegistry = apply {
+        knownNotations.add(notationName)
+    }
+
+    /**
+     * Return true if the notation name is registered in the registry.
+     *
+     * @param notationName name of the notation
+     * @return true if notation is known, false otherwise.
+     */
+    fun isKnownNotation(notationName: String): Boolean = knownNotations.contains(notationName)
+
+    /**
+     * Clear all known notations from the registry.
+     */
+    fun clear() {
+        knownNotations.clear()
+    }
+}