fix: remove leading zero bytes of dh secret

EspressifApp · Sep 25, 2024 · f72e88c · f72e88c
1 parent a4ecc8c
commit f72e88c
Showing 1 changed file with 23 additions and 3 deletions.
diff --git a/lib-blufi/src/main/java/blufi/espressif/security/BlufiDH.java b/lib-blufi/src/main/java/blufi/espressif/security/BlufiDH.java
@@ -1,5 +1,7 @@
 package blufi.espressif.security;
 
+import android.util.Log;
+
 import java.math.BigInteger;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
@@ -18,6 +20,8 @@
 import javax.crypto.spec.DHPublicKeySpec;
 
 public class BlufiDH {
+    private static final String TAG = "BlufiDH";
+
     private final BigInteger mP;
     private final BigInteger mG;
 
@@ -67,9 +71,25 @@ public void generateSecretKey(BigInteger y) {
             ka.doPhase(publicKey, true);
 
             // Generate the secret key
-            mSecretKey = ka.generateSecret();
+            byte[] tempSecret = ka.generateSecret();
+            int offset = 0;
+            for (byte b : tempSecret) {
+                if (b == 0) {
+                    offset++;
+                } else {
+                    break;
+                }
+            }
+            byte[] secretKey;
+            if (offset == 0) {
+                secretKey = tempSecret;
+            } else {
+                secretKey = new byte[tempSecret.length - offset];
+                System.arraycopy(tempSecret, offset, secretKey, 0, tempSecret.length - offset);
+            }
+            mSecretKey = secretKey;
         } catch (NoSuchAlgorithmException | InvalidKeySpecException | InvalidKeyException e) {
-            e.printStackTrace();
+            Log.w(TAG, e);
         }
     }
 
@@ -90,7 +110,7 @@ private static Key[] generateKeys(BigInteger p, BigInteger g, int length) {
         } catch (NoSuchAlgorithmException
                 | InvalidAlgorithmParameterException
                 | ClassCastException e) {
-            e.printStackTrace();
+            Log.w(TAG, e);
 
             return null;
         }