Add AEADAlgorithm class and test

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

@@ -0,0 +1,95 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.NoSuchElementException;
+
+/**
+ * List of AEAD algorithms defined in crypto-refresh-06.
+ *
+ * @see <a href="https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-06.html#name-aead-algorithms">
+ *     Crypto-Refresh-06 §9.6 - AEAD Algorithms</a>
+ */
+public enum AEADAlgorithm {
+
+    EAX(1, 16, 16),
+    OCB(2, 15, 16),
+    GCM(3, 12, 16),
+    ;
+
+    private final int algorithmId;
+    private final int ivLength;
+    private final int tagLength;
+
+    private static final Map<Integer, AEADAlgorithm> MAP = new HashMap<>();
+
+    static {
+        for (AEADAlgorithm h : AEADAlgorithm.values()) {
+            MAP.put(h.algorithmId, h);
+        }
+    }
+
+    AEADAlgorithm(int id, int ivLength, int tagLength) {
+        this.algorithmId = id;
+        this.ivLength = ivLength;
+        this.tagLength = tagLength;
+    }
+
+    public int getAlgorithmId() {
+        return algorithmId;
+    }
+
+    /**
+     * Return the length (in octets) of the IV.
+     *
+     * @return iv length
+     */
+    public int getIvLength() {
+        return ivLength;
+    }
+
+    /**
+     * Return the length (in octets) of the authentication tag.
+     *
+     * @return tag length
+     */
+    public int getTagLength() {
+        return tagLength;
+    }
+
+    /**
+     * Return the {@link AEADAlgorithm} value that corresponds to the provided algorithm id.
+     * If an invalid algorithm id was provided, null is returned.
+     *
+     * @param id numeric id
+     * @return enum value
+     */
+    @Nullable
+    public static AEADAlgorithm fromId(int id) {
+        return MAP.get(id);
+    }
+
+    /**
+     * Return the  {@link AEADAlgorithm} value that corresponds to the provided algorithm id.
+     * If an invalid algorithm id was provided, throw a {@link NoSuchElementException}.
+     *
+     * @param id algorithm id
+     * @return enum value
+     * @throws NoSuchElementException in case of an unknown algorithm id
+     */
+    @Nonnull
+    public static AEADAlgorithm requireFromId(int id) {
+        AEADAlgorithm algorithm = fromId(id);
+        if (algorithm == null) {
+            throw new NoSuchElementException("No AEADAlgorithm found for id " + id);
+        }
+        return algorithm;
+    }
+
+}

pgpainless-core/src/test/java/org/pgpainless/algorithm/AEADAlgorithmTest.java

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+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.NoSuchElementException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class AEADAlgorithmTest {
+
+    @Test
+    public void testEAXParameters() {
+        AEADAlgorithm eax = AEADAlgorithm.EAX;
+        assertEquals(1, eax.getAlgorithmId());
+        assertEquals(16, eax.getIvLength());
+        assertEquals(16, eax.getTagLength());
+    }
+
+    @Test
+    public void testOCBParameters() {
+        AEADAlgorithm ocb = AEADAlgorithm.OCB;
+        assertEquals(2, ocb.getAlgorithmId());
+        assertEquals(15, ocb.getIvLength());
+        assertEquals(16, ocb.getTagLength());
+    }
+
+    @Test
+    public void testGCMParameters() {
+        AEADAlgorithm gcm = AEADAlgorithm.GCM;
+        assertEquals(3, gcm.getAlgorithmId());
+        assertEquals(12, gcm.getIvLength());
+        assertEquals(16, gcm.getTagLength());
+    }
+
+    @Test
+    public void testFromId() {
+        assertEquals(AEADAlgorithm.EAX, AEADAlgorithm.requireFromId(1));
+        assertEquals(AEADAlgorithm.OCB, AEADAlgorithm.requireFromId(2));
+        assertEquals(AEADAlgorithm.GCM, AEADAlgorithm.requireFromId(3));
+
+        assertNull(AEADAlgorithm.fromId(99));
+        assertThrows(NoSuchElementException.class, () -> AEADAlgorithm.requireFromId(99));
+    }
+}