Add Android P support for SecureCredentialsManager

auth0/src/main/java/com/auth0/android/authentication/storage/CryptoUtil.java

@@ -85,7 +85,7 @@ KeyStore.PrivateKeyEntry getRSAKeyEntry() throws KeyException {
             keyStore.load(null);
             if (keyStore.containsAlias(KEY_ALIAS)) {
                 //Return existing key
-                return (KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
+                return getKeyEntryCompat(keyStore);
             }
 
             Calendar start = Calendar.getInstance();
@@ -133,7 +133,8 @@ KeyStore.PrivateKeyEntry getRSAKeyEntry() throws KeyException {
             KeyPairGenerator generator = KeyPairGenerator.getInstance(ALGORITHM_RSA, ANDROID_KEY_STORE);
             generator.initialize(spec);
             generator.generateKeyPair();
-            return (KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
+
+            return getKeyEntryCompat(keyStore);
         } catch (KeyStoreException | IOException | NoSuchProviderException | InvalidAlgorithmParameterException | NoSuchAlgorithmException | CertificateException e) {
             Log.e(TAG, "An error occurred while trying to obtain the RSA KeyPair Entry from the Android KeyStore.", e);
             throw new KeyException("An error occurred while trying to obtain the RSA KeyPair Entry from the Android KeyStore.", e);
@@ -145,6 +146,21 @@ KeyStore.PrivateKeyEntry getRSAKeyEntry() throws KeyException {
         }
     }
 
+    private KeyStore.PrivateKeyEntry getKeyEntryCompat(KeyStore keyStore) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableEntryException {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.P) {
+            return (KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
+        }
+
+        //Following code is for API 28+
+        PrivateKey privateKey = (PrivateKey) keyStore.getKey(KEY_ALIAS, null);
+
+        if (privateKey == null) {
+            return (KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
+        }
+
+        Certificate certificate = keyStore.getCertificate(KEY_ALIAS);
+        return new KeyStore.PrivateKeyEntry(privateKey, new Certificate[]{certificate});
+    }
 
     //Used to delete recreate the key pair in case of error
     private void deleteKeys() {

auth0/src/test/java/com/auth0/android/authentication/storage/CryptoUtilTest.java

@@ -300,6 +300,54 @@ public void shouldCreateRSAKeyPairIfMissingOnAPI23AndUp() throws Exception {
         ArgumentCaptor<Date> endDateCaptor = ArgumentCaptor.forClass(Date.class);
 
 
+        final KeyStore.PrivateKeyEntry entry = cryptoUtil.getRSAKeyEntry();
+
+
+        Mockito.verify(builder).setKeySize(2048);
+        Mockito.verify(builder).setCertificateSubject(principalCaptor.capture());
+        Mockito.verify(builder).setCertificateSerialNumber(BigInteger.ONE);
+        Mockito.verify(builder).setCertificateNotBefore(startDateCaptor.capture());
+        Mockito.verify(builder).setCertificateNotAfter(endDateCaptor.capture());
+        Mockito.verify(builder).setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_PKCS1);
+        Mockito.verify(builder).setBlockModes(KeyProperties.BLOCK_MODE_ECB);
+        Mockito.verify(keyPairGenerator).initialize(spec);
+        Mockito.verify(keyPairGenerator).generateKeyPair();
+
+        assertThat(principalCaptor.getValue(), is(notNullValue()));
+        assertThat(principalCaptor.getValue().getName(), is(CERTIFICATE_PRINCIPAL));
+
+        assertThat(startDateCaptor.getValue(), is(notNullValue()));
+        long diffMillis = startDateCaptor.getValue().getTime() - new Date().getTime();
+        long days = TimeUnit.MILLISECONDS.toDays(diffMillis);
+        assertThat(days, is(0L)); //Date is Today
+
+        assertThat(endDateCaptor.getValue(), is(notNullValue()));
+        diffMillis = endDateCaptor.getValue().getTime() - new Date().getTime();
+        days = TimeUnit.MILLISECONDS.toDays(diffMillis);
+        assertThat(days, is(greaterThan(25 * 365L))); //Date more than 25 Years in days
+
+        assertThat(entry, is(expectedEntry));
+    }
+
+    @RequiresApi(api = Build.VERSION_CODES.P)
+    @Test
+    @Config(sdk = 28)
+    public void shouldCreateRSAKeyPairIfMissingOnAPI28AndUp() throws Exception {
+        ReflectionHelpers.setStaticField(Build.VERSION.class, "SDK_INT", 28);
+
+        PowerMockito.when(keyStore.containsAlias(KEY_ALIAS)).thenReturn(false);
+        KeyStore.PrivateKeyEntry expectedEntry = PowerMockito.mock(KeyStore.PrivateKeyEntry.class);
+        PowerMockito.when(keyStore.getEntry(KEY_ALIAS, null)).thenReturn(expectedEntry);
+
+        KeyGenParameterSpec spec = PowerMockito.mock(KeyGenParameterSpec.class);
+        KeyGenParameterSpec.Builder builder = newKeyGenParameterSpecBuilder(spec);
+        PowerMockito.whenNew(KeyGenParameterSpec.Builder.class).withArguments(KEY_ALIAS, KeyProperties.PURPOSE_DECRYPT | KeyProperties.PURPOSE_ENCRYPT).thenReturn(builder);
+
+        ArgumentCaptor<X500Principal> principalCaptor = ArgumentCaptor.forClass(X500Principal.class);
+        ArgumentCaptor<Date> startDateCaptor = ArgumentCaptor.forClass(Date.class);
+        ArgumentCaptor<Date> endDateCaptor = ArgumentCaptor.forClass(Date.class);
+
+
         final KeyStore.PrivateKeyEntry entry = cryptoUtil.getRSAKeyEntry();
 
         Mockito.verify(builder).setKeySize(2048);
@@ -879,4 +927,4 @@ public Cipher answer(InvocationOnMock invocation) throws Throwable {
         });
         return cryptoUtil;
     }
-}
+}