diff --git a/app/src/full/java/org/fdroid/fdroid/nearby/LocalRepoKeyStore.java b/app/src/full/java/org/fdroid/fdroid/nearby/LocalRepoKeyStore.java
index 94ce9e6d7..8ae2812ee 100644
--- a/app/src/full/java/org/fdroid/fdroid/nearby/LocalRepoKeyStore.java
+++ b/app/src/full/java/org/fdroid/fdroid/nearby/LocalRepoKeyStore.java
@@ -62,7 +62,7 @@ public final class LocalRepoKeyStore {
     private static final String INDEX_CERT_ALIAS = "fdroid";
     private static final String HTTP_CERT_ALIAS = "https";
 
-    private static final String DEFAULT_SIG_ALG = "SHA1withRSA";
+    public static final String DEFAULT_SIG_ALG = "SHA1withRSA";
     private static final String DEFAULT_KEY_ALGO = "RSA";
     private static final int DEFAULT_KEY_BITS = 2048;
 
@@ -277,18 +277,18 @@ public final class LocalRepoKeyStore {
         };
     }
 
-    private KeyPair generateRandomKeypair() throws NoSuchAlgorithmException {
+    public static KeyPair generateRandomKeypair() throws NoSuchAlgorithmException {
         KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(DEFAULT_KEY_ALGO);
         keyPairGenerator.initialize(DEFAULT_KEY_BITS);
         return keyPairGenerator.generateKeyPair();
     }
 
-    private Certificate generateSelfSignedCertChain(KeyPair kp, X500Name subject)
+    public static Certificate generateSelfSignedCertChain(KeyPair kp, X500Name subject)
             throws CertificateException, OperatorCreationException, IOException {
         return generateSelfSignedCertChain(kp, subject, null);
     }
 
-    private Certificate generateSelfSignedCertChain(KeyPair kp, X500Name subject, String hostname)
+    public static Certificate generateSelfSignedCertChain(KeyPair kp, X500Name subject, String hostname)
             throws CertificateException, OperatorCreationException, IOException {
         SecureRandom rand = new SecureRandom();
         PrivateKey privKey = kp.getPrivate();
diff --git a/app/src/testFull/java/kellinwood/security/zipsigner/ZipSignerTest.java b/app/src/testFull/java/kellinwood/security/zipsigner/ZipSignerTest.java
new file mode 100644
index 000000000..e50965e56
--- /dev/null
+++ b/app/src/testFull/java/kellinwood/security/zipsigner/ZipSignerTest.java
@@ -0,0 +1,96 @@
+package kellinwood.security.zipsigner;
+
+import kellinwood.security.zipsigner.ZipSigner;
+import org.apache.commons.io.IOUtils;
+import org.bouncycastle.asn1.x500.X500Name;
+import org.bouncycastle.operator.OperatorCreationException;
+import org.fdroid.fdroid.nearby.LocalRepoKeyStore;
+import org.fdroid.index.v1.IndexV1VerifierKt;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.Robolectric;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+import org.robolectric.shadows.ShadowLog;
+
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+import java.security.KeyPair;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+/**
+ * This test the JAR signing functions of {@link ZipSigner}.
+ */
+@RunWith(RobolectricTestRunner.class)
+@Config(sdk={23, 25, 32}) // minSdkVersion, targetSdkVersion, max SDK supported by Robolectric
+public class ZipSignerTest {
+    public static final String TAG = "ZipSignerTest";
+
+    private File unsigned;
+    private File signed;
+    
+    @Before
+    public void setUp() {
+        ShadowLog.stream = System.out;
+        try {
+            unsigned = File.createTempFile(getClass().getName(), "unsigned.jar");
+            BufferedOutputStream bo = new BufferedOutputStream(new FileOutputStream(unsigned));
+            JarOutputStream jo = new JarOutputStream(bo);
+            JarEntry je = new JarEntry(IndexV1VerifierKt.DATA_FILE_NAME);
+            jo.putNextEntry(je);
+            IOUtils.write("{\"fake\": \"json\"}", jo);
+            jo.flush();
+            jo.close();
+            bo.close();
+        } catch (IOException e) {
+            fail();
+        }
+    }
+    
+    @After
+    public void tearDown() {
+        if (unsigned != null) {
+            unsigned.delete();
+        }
+        if (signed != null) {
+            signed.delete();
+        }
+    }
+
+    @Test
+    public void testSignApk()
+        throws CertificateException, ClassNotFoundException, GeneralSecurityException, IllegalAccessException, InstantiationException, IOException, NoSuchAlgorithmException, OperatorCreationException {
+ 
+        System.out.println("wrote " + unsigned);
+        assertTrue(unsigned.exists());
+        assertTrue(unsigned.length() > 0);
+
+        ZipSigner zipSigner = new ZipSigner();
+        KeyPair keys = LocalRepoKeyStore.generateRandomKeypair();
+        PrivateKey privateKey = keys.getPrivate();
+        X500Name subject = new X500Name("O=test,OU=suite");
+        X509Certificate cert = (X509Certificate) LocalRepoKeyStore.generateSelfSignedCertChain(keys, subject);
+        File signed = File.createTempFile(getClass().getName(), "signed.jar");
+
+        zipSigner.setKeys("test", cert, privateKey, LocalRepoKeyStore.DEFAULT_SIG_ALG, null);
+        zipSigner.signZip(unsigned.getAbsolutePath(), signed.getAbsolutePath());
+        System.out.println("signed " + unsigned + " into " + signed);
+
+        assertTrue(signed.exists());
+        assertTrue(signed.length() > unsigned.length());
+   }
+}
diff --git a/app/src/testFull/java/org/fdroid/fdroid/nearby/LocalRepoKeyStoreTest.java b/app/src/testFull/java/org/fdroid/fdroid/nearby/LocalRepoKeyStoreTest.java
index 1f6ebaa3b..62cc5a104 100644
--- a/app/src/testFull/java/org/fdroid/fdroid/nearby/LocalRepoKeyStoreTest.java
+++ b/app/src/testFull/java/org/fdroid/fdroid/nearby/LocalRepoKeyStoreTest.java
@@ -11,6 +11,7 @@ import org.fdroid.index.v1.IndexV1VerifierKt;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
 
 import java.io.BufferedOutputStream;
 import java.io.File;
@@ -29,6 +30,7 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 
 @RunWith(RobolectricTestRunner.class)
+@Config(sdk={23, 25, 32}) // minSdkVersion, targetSdkVersion, max SDK supported by Robolectric
 public class LocalRepoKeyStoreTest {
 
     @Test