diff --git a/src/main/java/ganarchy/friendcode/util/ConfigUtil.java b/src/main/java/ganarchy/friendcode/util/ConfigUtil.java
index b2d6af2..66d497f 100644
--- a/src/main/java/ganarchy/friendcode/util/ConfigUtil.java
+++ b/src/main/java/ganarchy/friendcode/util/ConfigUtil.java
@@ -22,8 +22,9 @@ public class ConfigUtil {
* The message stored in the config. Could probably use some improvement.
*/
private static final String CONFIG_MESSAGE =
- "This is the friendcode config file."
- + " It's created when you open your world to a friend code.";
+ "THIS FILE CONTAINS SECRETS! This is the friendcode config file."
+ + " It's created when you open your world to a friend code."
+ + " Keep it private. And make a backup.";
/**
* The (cached) global friendcode config dir.
*/
diff --git a/src/main/java/ganarchy/friendcode/util/KeyUtil.java b/src/main/java/ganarchy/friendcode/util/KeyUtil.java
index ab5d614..79a6a45 100644
--- a/src/main/java/ganarchy/friendcode/util/KeyUtil.java
+++ b/src/main/java/ganarchy/friendcode/util/KeyUtil.java
@@ -1,11 +1,27 @@
package ganarchy.friendcode.util;
+import org.apache.commons.codec.binary.Base64;
+
+import javax.crypto.*;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
import java.nio.file.Path;
+import java.security.*;
+import java.util.Properties;
/**
* Helper to deal with private keys.
*/
public class KeyUtil {
+ // it is important to use encryption, as you don't want random users
+ // hosting the world code. by encrypting the world code to an user, it
+ // prevents that.
+ // then you can freely share the world files and nothing bad happens.
+
/**
* Reads and decrypts a private key file.
*
@@ -13,18 +29,101 @@ public class KeyUtil {
* @return The decrypted private key, or null if it doesn't exist.
*/
public static String readKeyFile(Path keyFile) {
- return null;
+ byte[] file;
+ byte[] out;
+ try {
+ file = Files.readAllBytes(keyFile);
+ } catch (IOException e) {
+ return null;
+ }
+ if (file.length < 12 + 16 + 884) { // 12 (IV) + 16 (tag) + 884 (key)
+ return null;
+ }
+ try {
+ var c = Cipher.getInstance("AES/GCM/NoPadding");
+ Key key = getGlobalKey();
+ byte[] iv = new byte[12];
+ System.arraycopy(file, 0, iv, 0, 12);
+ c.init(Cipher.DECRYPT_MODE, key, new GCMParameterSpec(128, iv));
+ out = c.doFinal(file, 12, file.length - 12);
+ } catch (AEADBadTagException e) {
+ return null;
+ } catch (
+ NoSuchAlgorithmException | NoSuchPaddingException
+ | InvalidAlgorithmParameterException | InvalidKeyException
+ | IllegalBlockSizeException | BadPaddingException e
+ ) {
+ throw new RuntimeException(e);
+ }
+ return StandardCharsets.UTF_8.decode(ByteBuffer.wrap(out)).toString();
}
/**
* Encrypts and writes a private key file.
*
- * @param keyFile The path to the key file.
- * @param key The private key.
+ * @param keyFile The path to the key file.
+ * @param privateKey The private key.
* @return Whether writing the key succeeded.
*/
- public static boolean writeKeyFile(Path keyFile, String key) {
- return false;
+ public static boolean writeKeyFile(Path keyFile, String privateKey) {
+ byte[] in = privateKey.getBytes(StandardCharsets.UTF_8);
+ byte[] iv = new byte[12];
+ byte[] out;
+ try {
+ var c = Cipher.getInstance("AES/GCM/NoPadding");
+ Key key = getGlobalKey();
+ var rand = new SecureRandom();
+ rand.nextBytes(iv);
+ c.init(Cipher.ENCRYPT_MODE, key, new GCMParameterSpec(128, iv));
+ out = c.doFinal(in, 0, in.length);
+ } catch (
+ NoSuchAlgorithmException | NoSuchPaddingException
+ | InvalidAlgorithmParameterException | InvalidKeyException
+ | IllegalBlockSizeException | BadPaddingException e
+ ) {
+ throw new RuntimeException(e);
+ }
+ try (var file = Files.newOutputStream(keyFile)) {
+ file.write(iv);
+ file.write(out);
+ file.flush();
+ return true;
+ } catch (IOException e) {
+ return false;
+ }
+ }
+
+ /**
+ * Returns the global key used for the encryption/decryption of world keys.
+ */
+ private static Key getGlobalKey() {
+ Properties prop = new Properties();
+ if (ConfigUtil.getSettings(prop)) {
+ var key = prop.getProperty("key.aes");
+ if (key != null) {
+ byte[] bytes = null;
+ try {
+ bytes = Base64.decodeBase64(key);
+ } catch (IllegalArgumentException ignored) {
+ }
+ if (bytes != null && bytes.length == 16) {
+ return new SecretKeySpec(bytes, "AES");
+ }
+ }
+ }
+ prop.clear();
+ try {
+ var gen = KeyGenerator.getInstance("AES");
+ gen.init(128);
+ Key key = gen.generateKey();
+ var encoded = Base64.encodeBase64String(key.getEncoded());
+ prop.setProperty("key.aes", encoded);
+ // if the key didn't save we'll just regen world codes.
+ ConfigUtil.updateSettings(prop);
+ return key;
+ } catch (NoSuchAlgorithmException e) {
+ throw new RuntimeException(e);
+ }
}
}
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