Maven (#9)

src/main/java/de/caydenno1/xacrypto/encryption/AES_GCM.java

@@ -0,0 +1,52 @@
+package de.caydenno1.xacrypto.encryption;
+
+import javax.crypto.Cipher;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+public class AES_GCM {
+    private static final String AES = "AES";
+    private static final String AES_GCM = "AES/GCM/NoPadding";
+
+    private AES_GCM() {}
+
+    public static SecretKey genKey(int bits) throws Exception {
+        KeyGenerator g = KeyGenerator.getInstance(AES);
+        g.init(bits);
+
+        return g.generateKey();
+    }
+
+    public static String encrypt(String pln, SecretKey k, int TAG, int IV) throws Exception {
+        byte[] iv = new byte[IV];
+        new SecureRandom().nextBytes(iv);
+
+        Cipher c  = Cipher.getInstance(AES_GCM);
+        c.init(Cipher.ENCRYPT_MODE, k, new GCMParameterSpec(TAG, iv));
+
+        byte[] citext = c.doFinal(pln.getBytes());
+
+        byte[] comb = new byte[iv.length + citext.length];
+        System.arraycopy(iv, 0, comb, 0, iv.length);
+        System.arraycopy(citext, 0, comb, iv.length, citext.length);
+
+        return Base64.getEncoder().encodeToString(comb);
+    }
+
+    public static String decrypt(String enc, SecretKey k, int TAG, int IV) throws Exception {
+        byte[] dat = Base64.getDecoder().decode(enc);
+
+        byte[] iv = new byte[IV];
+        byte[] cit = new byte[dat.length - IV];
+
+        System.arraycopy(dat, 0, iv, 0, IV);
+        System.arraycopy(dat, IV, cit, 0, cit.length);
+
+        Cipher ci = Cipher.getInstance(AES_GCM);
+        ci.init(Cipher.DECRYPT_MODE, k, new GCMParameterSpec(TAG, iv));
+        return new String(ci.doFinal(cit));
+    }
+}