Kotlin conversion: SecretKeyPassphraseProvider and subclasses

This commit also adds a workaround to build.gradle which enables proper Java interop for
Kotlin interfaces with default implementations

build.gradle

@@ -67,6 +67,13 @@ allprojects {
         fileMode = 0644
     }
 
+    // Compatibility of default implementations in kotlin interfaces with Java implementations.
+    tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
+        kotlinOptions {
+            freeCompilerArgs += ["-Xjvm-default=all-compatibility"]
+        }
+    }
+
     project.ext {
         rootConfigDir = new File(rootDir, 'config')
         gitCommit = getGitCommit()

pgpainless-core/src/main/java/org/pgpainless/key/protection/package-info.java

@@ -1,8 +0,0 @@
-// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-/**
- * Classes related to OpenPGP secret key password protection.
- */
-package org.pgpainless.key.protection;

pgpainless-core/src/main/java/org/pgpainless/key/protection/passphrase_provider/MapBasedPassphraseProvider.java

@@ -1,42 +0,0 @@
-// SPDX-FileCopyrightText: 2020 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.key.protection.passphrase_provider;
-
-import java.util.Map;
-import javax.annotation.Nullable;
-
-import org.pgpainless.util.Passphrase;
-
-/**
- * Implementation of the {@link SecretKeyPassphraseProvider} that holds a map of different {@link Passphrase passphrases}.
- * It will return the right passphrase depending on the key-id.
- *
- * Note: This provider might return null!
- * TODO: Make this null-safe and throw an exception instead?
- */
-public class MapBasedPassphraseProvider implements SecretKeyPassphraseProvider {
-
-    private final Map<Long, Passphrase> map;
-
-    /**
-     * Create a new map based passphrase provider.
-     *
-     * @param passphraseMap map of key-ids and passphrases
-     */
-    public MapBasedPassphraseProvider(Map<Long, Passphrase> passphraseMap) {
-        this.map = passphraseMap;
-    }
-
-    @Nullable
-    @Override
-    public Passphrase getPassphraseFor(long keyId) {
-        return map.get(keyId);
-    }
-
-    @Override
-    public boolean hasPassphrase(long keyId) {
-        return map.containsKey(keyId);
-    }
-}

pgpainless-core/src/main/java/org/pgpainless/key/protection/passphrase_provider/SecretKeyPassphraseProvider.java

@@ -1,40 +0,0 @@
-// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.key.protection.passphrase_provider;
-
-import javax.annotation.Nullable;
-
-import org.bouncycastle.openpgp.PGPSecretKey;
-import org.pgpainless.util.Passphrase;
-
-/**
- * Interface to allow the user to provide a {@link Passphrase} for an encrypted OpenPGP secret key.
- */
-public interface SecretKeyPassphraseProvider {
-
-    /**
-     * Return a passphrase for the given secret key.
-     * If no record is found, return null.
-     * Note: In case of an unprotected secret key, this method must may not return null, but a {@link Passphrase} with
-     * a content of null.
-     *
-     * @param secretKey secret key
-     * @return passphrase or null, if no passphrase record is found.
-     */
-    @Nullable default Passphrase getPassphraseFor(PGPSecretKey secretKey) {
-        return getPassphraseFor(secretKey.getKeyID());
-    }
-    /**
-     * Return a passphrase for the given key. If no record has been found, return null.
-     * Note: In case of an unprotected secret key, this method must may not return null, but a {@link Passphrase} with
-     * a content of null.
-     *
-     * @param keyId if of the secret key
-     * @return passphrase or null, if no passphrase record has been found.
-     */
-    @Nullable Passphrase getPassphraseFor(long keyId);
-
-    boolean hasPassphrase(long keyId);
-}

pgpainless-core/src/main/java/org/pgpainless/key/protection/passphrase_provider/SolitaryPassphraseProvider.java

@@ -1,33 +0,0 @@
-// SPDX-FileCopyrightText: 2020 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.key.protection.passphrase_provider;
-
-import javax.annotation.Nullable;
-
-import org.pgpainless.util.Passphrase;
-
-/**
- * Implementation of the {@link SecretKeyPassphraseProvider} that holds a single {@link Passphrase}.
- */
-public class SolitaryPassphraseProvider implements SecretKeyPassphraseProvider {
-
-    private final Passphrase passphrase;
-
-    public SolitaryPassphraseProvider(Passphrase passphrase) {
-        this.passphrase = passphrase;
-    }
-
-    @Nullable
-    @Override
-    public Passphrase getPassphraseFor(long keyId) {
-        // always return the same passphrase.
-        return passphrase;
-    }
-
-    @Override
-    public boolean hasPassphrase(long keyId) {
-        return true;
-    }
-}

pgpainless-core/src/main/java/org/pgpainless/key/protection/passphrase_provider/package-info.java

@@ -1,8 +0,0 @@
-// SPDX-FileCopyrightText: 2020 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-/**
- * Passphrase Provider classes.
- */
-package org.pgpainless.key.protection.passphrase_provider;

pgpainless-core/src/main/kotlin/org/pgpainless/key/protection/passphrase_provider/MapBasedPassphraseProvider.kt

@@ -0,0 +1,21 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.protection.passphrase_provider
+
+import org.pgpainless.util.Passphrase
+
+/**
+ * Implementation of the [SecretKeyPassphraseProvider] that holds a map of key-IDs and respective [Passphrase].
+ * It will return the right passphrase depending on the key-id.
+ *
+ * Note: This provider might return null!
+ * TODO: Make this null-safe and throw an exception instead?
+ */
+class MapBasedPassphraseProvider(val map: Map<Long, Passphrase>) : SecretKeyPassphraseProvider {
+
+    override fun getPassphraseFor(keyId: Long): Passphrase? = map[keyId]
+
+    override fun hasPassphrase(keyId: Long): Boolean = map.containsKey(keyId)
+}

pgpainless-core/src/main/kotlin/org/pgpainless/key/protection/passphrase_provider/SecretKeyPassphraseProvider.kt

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.protection.passphrase_provider
+
+import org.bouncycastle.openpgp.PGPSecretKey
+import org.pgpainless.util.Passphrase
+
+/**
+ * Interface to allow the user to provide a [Passphrase] for an encrypted OpenPGP secret key.
+ */
+interface SecretKeyPassphraseProvider {
+
+    /**
+     * Return a passphrase for the given secret key.
+     * If no record is found, return null.
+     * Note: In case of an unprotected secret key, this method must may not return null, but a [Passphrase] with
+     * a content of null.
+     *
+     * @param secretKey secret key
+     * @return passphrase or null, if no passphrase record is found.
+     */
+    fun getPassphraseFor(secretKey: PGPSecretKey): Passphrase? {
+        return getPassphraseFor(secretKey.keyID)
+    }
+
+    /**
+     * Return a passphrase for the given key. If no record has been found, return null.
+     * Note: In case of an unprotected secret key, this method must may not return null, but a [Passphrase] with
+     * a content of null.
+     *
+     * @param keyId if of the secret key
+     * @return passphrase or null, if no passphrase record has been found.
+     */
+    fun getPassphraseFor(keyId: Long): Passphrase?
+
+    fun hasPassphrase(keyId: Long): Boolean
+}

pgpainless-core/src/main/kotlin/org/pgpainless/key/protection/passphrase_provider/SolitaryPassphraseProvider.kt

@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.protection.passphrase_provider
+
+import org.pgpainless.util.Passphrase
+
+/**
+ * Implementation of the [SecretKeyPassphraseProvider] that holds a single [Passphrase].
+ */
+class SolitaryPassphraseProvider(val passphrase: Passphrase?) : SecretKeyPassphraseProvider {
+
+    override fun getPassphraseFor(keyId: Long): Passphrase? = passphrase
+
+    override fun hasPassphrase(keyId: Long): Boolean = true
+}