Crypto: Bad Mac use tests, and fix for BadMacOrderMacOnEncryptPlaintext (barriers were blocking flow through an encrypt to a subsequent mac on the same plaintext)

java/ql/src/experimental/quantum/Examples/BadMacOrderMacOnEncryptPlaintext.ql

@@ -28,14 +28,6 @@ module CommonDataFlowNodeConfig implements DataFlow::ConfigSig {
     sink = any(Crypto::FlowAwareElement other).getInputNode()
   }
 
-  predicate isBarrierOut(DataFlow::Node node) {
-    node = any(Crypto::FlowAwareElement element).getInputNode()
-  }
-
-  predicate isBarrierIn(DataFlow::Node node) {
-    node = any(Crypto::FlowAwareElement element).getOutputNode()
-  }
-
   predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
     node1.(AdditionalFlowInputStep).getOutput() = node2
     or

java/ql/test/experimental/query-tests/quantum/examples/BadMacUse/BadMacOrderDecryptToMac.qlref

@@ -0,0 +1,4 @@
+query: experimental/quantum/Examples/BadMacOrderDecryptToMac.ql
+postprocess:
+  - utils/test/PrettyPrintModels.ql
+  - utils/test/InlineExpectationsTestQuery.ql

java/ql/test/experimental/query-tests/quantum/examples/BadMacUse/BadMacOrderMacOnEncryptPlaintext.qlref

@@ -0,0 +1,4 @@
+query: experimental/quantum/Examples/BadMacOrderMacOnEncryptPlaintext.ql
+postprocess:
+  - utils/test/PrettyPrintModels.ql
+  - utils/test/InlineExpectationsTestQuery.ql

java/ql/test/experimental/query-tests/quantum/examples/BadMacUse/BadMacUse.java

@@ -0,0 +1,87 @@
+import java.security.*;
+import java.util.Arrays;
+import java.util.Base64;
+import javax.crypto.Cipher;
+import javax.crypto.KeyGenerator;
+import javax.crypto.Mac;
+import javax.crypto.SecretKey;
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.PBEKeySpec;
+import javax.crypto.spec.SecretKeySpec;
+
+
+class BadMacUse {
+
+    private byte[] generateSalt(int length) {
+        byte[] salt = new byte[length];
+        new SecureRandom().nextBytes(salt);
+        return salt;
+    }
+   
+    public void CipherThenMac(byte[] encryptionKeyBytes, byte[] macKeyBytes) throws Exception {
+        // Create keys directly from provided byte arrays
+        SecretKey encryptionKey = new SecretKeySpec(encryptionKeyBytes, "AES");
+        SecretKey macKey = new SecretKeySpec(macKeyBytes, "HmacSHA256");
+
+        // Encrypt some sample data using the encryption key
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+        cipher.init(Cipher.ENCRYPT_MODE, encryptionKey, new SecureRandom());
+        byte[] plaintext = "Further Use Test Data".getBytes();
+        byte[] ciphertext = cipher.doFinal(plaintext);
+
+        // Compute HMAC over the ciphertext using the MAC key
+        Mac mac = Mac.getInstance("HmacSHA256");
+        mac.init(macKey);
+        byte[] computedMac = mac.doFinal(ciphertext);
+
+        // Concatenate ciphertext and MAC
+        byte[] output = new byte[ciphertext.length + computedMac.length];
+        System.arraycopy(ciphertext, 0, output, 0, ciphertext.length);
+        System.arraycopy(computedMac, 0, output, ciphertext.length, computedMac.length);
+    }
+
+
+    public void BadDecryptThenMacOnPlaintextVerify(byte[] encryptionKeyBytes, byte[] macKeyBytes, byte[] input) throws Exception {
+        // Split input into ciphertext and MAC
+        int macLength = 32; // HMAC-SHA256 output length
+        byte[] ciphertext = Arrays.copyOfRange(input, 0, input.length - macLength);
+        byte[] receivedMac = Arrays.copyOfRange(input, input.length - macLength, input.length);
+
+        // Decrypt first (unsafe)
+        SecretKey encryptionKey = new SecretKeySpec(encryptionKeyBytes, "AES");
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+        cipher.init(Cipher.DECRYPT_MODE, encryptionKey, new SecureRandom());
+        byte[] plaintext = cipher.doFinal(ciphertext); // $Source
+
+        // Now verify MAC (too late)
+        SecretKey macKey = new SecretKeySpec(macKeyBytes, "HmacSHA256");
+        Mac mac = Mac.getInstance("HmacSHA256");
+        mac.init(macKey);
+        byte[] computedMac = mac.doFinal(plaintext); // $Alert[java/quantum/bad-mac-order-decrypt-to-mac]
+
+        if (!MessageDigest.isEqual(receivedMac, computedMac)) {
+            throw new SecurityException("MAC verification failed");
+        }
+    }
+
+    public void BadMacOnPlaintext(byte[] encryptionKeyBytes, byte[] macKeyBytes, byte[] plaintext) throws Exception {// $Alert[java/quantum/bad-mac-order-encrypt-plaintext-also-in-mac]
+        // Create keys directly from provided byte arrays
+        SecretKey encryptionKey = new SecretKeySpec(encryptionKeyBytes, "AES");
+        SecretKey macKey = new SecretKeySpec(macKeyBytes, "HmacSHA256");
+
+        // BAD Compute MAC over plaintext (not ciphertext)
+        Mac mac = Mac.getInstance("HmacSHA256");
+        mac.init(macKey);
+        byte[] computedMac = mac.doFinal(plaintext); // Integrity not tied to encrypted data
+
+        // Encrypt the plaintext
+        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
+        cipher.init(Cipher.ENCRYPT_MODE, encryptionKey, new SecureRandom());
+        byte[] ciphertext = cipher.doFinal(plaintext);
+
+        // Concatenate ciphertext and MAC
+        byte[] output = new byte[ciphertext.length + computedMac.length];
+        System.arraycopy(ciphertext, 0, output, 0, ciphertext.length);
+        System.arraycopy(computedMac, 0, output, ciphertext.length, computedMac.length);
+    }
+}