add hint if public key derivation is optimized or not

APPLICATION.MD

@@ -69,6 +69,7 @@ Response Data format:
   - Tag 0xC0 = PIN retry count (1 byte)
   - Tag 0xC1 = PUK retry count (1 byte)
   - Tag 0xC2 = 0 if key is not initialized, 1 otherwise
+  - Tag 0xC3 = 1 if public key derivation is hw optimized, 0 otherwise
 
 ### VERIFY PIN
 

src/main/java/im/status/wallet/SEC256k1.java

@@ -90,4 +90,8 @@ public class SEC256k1 {
       return ecPoint.getW(out, outOff);
     }
   }
+
+  static boolean hasFastECPointMultiplication() {
+    return ecPointMultiplier != null;
+  }
 }

src/main/java/im/status/wallet/WalletApplet.java

@@ -47,6 +47,7 @@ public class WalletApplet extends Applet {
   static final byte TLV_PIN_RETRY_COUNT = (byte) 0xC0;
   static final byte TLV_PUK_RETRY_COUNT = (byte) 0xC1;
   static final byte TLV_KEY_INITIALIZATION_STATUS = (byte) 0xC2;
+  static final byte TLV_FAST_PUBLIC_KEY_DERIVATION = (byte) 0xC3;
 
   private OwnerPIN pin;
   private OwnerPIN puk;
@@ -175,6 +176,9 @@ public class WalletApplet extends Applet {
     apduBuffer[off++] = TLV_KEY_INITIALIZATION_STATUS;
     apduBuffer[off++] = 1;
     apduBuffer[off++] = privateKey.isInitialized() ? (byte) 0x01 : (byte) 0x00;
+    apduBuffer[off++] = TLV_FAST_PUBLIC_KEY_DERIVATION;
+    apduBuffer[off++] = 1;
+    apduBuffer[off++] = SEC256k1.hasFastECPointMultiplication() ? (byte) 0x01 : (byte) 0x00;
 
     short len = secureChannel.encryptAPDU(apduBuffer, (short) (off - SecureChannel.SC_OUT_OFFSET));
     apdu.setOutgoingAndSend(ISO7816.OFFSET_CDATA, len);

src/test/java/im/status/wallet/WalletAppletTest.java

@@ -117,24 +117,25 @@ public class WalletAppletTest {
     cmdSet.openSecureChannel();
 
     // Good case. Since the order of test execution is undefined, the test cannot know if the keys are initialized or not.
+    // Additionally, support for fast public key derivation is hw dependent.
     response = cmdSet.getStatus();
     assertEquals(0x9000, response.getSW());
     byte[] data = secureChannel.decryptAPDU(response.getData());
-    assertTrue(Hex.toHexString(data).matches("a309c00103c10105c2010[0-1]"));
+    assertTrue(Hex.toHexString(data).matches("a309c00103c10105c2010[0-1]c3010[0-1]"));
 
     response = cmdSet.verifyPIN("123456");
     assertEquals(0x63C2, response.getSW());
     response = cmdSet.getStatus();
     assertEquals(0x9000, response.getSW());
     data = secureChannel.decryptAPDU(response.getData());
-    assertTrue(Hex.toHexString(data).matches("a309c00102c10105c2010[0-1]"));
+    assertTrue(Hex.toHexString(data).matches("a309c00102c10105c2010[0-1]c3010[0-1]"));
 
     response = cmdSet.verifyPIN("000000");
     assertEquals(0x9000, response.getSW());
     response = cmdSet.getStatus();
     assertEquals(0x9000, response.getSW());
     data = secureChannel.decryptAPDU(response.getData());
-    assertTrue(Hex.toHexString(data).matches("a309c00103c10105c2010[0-1]"));
+    assertTrue(Hex.toHexString(data).matches("a309c00103c10105c2010[0-1]c3010[0-1]"));
   }
 
   @Test
@@ -396,14 +397,21 @@ public class WalletAppletTest {
     response = cmdSet.sign(data, WalletApplet.SIGN_P1_DATA,false, true);
     assertEquals(0x6A86, response.getSW());
 
-    // Correctly sign 1 block (P2: 0x81)
+    // Correctly sign a precomputed hash
-    response = cmdSet.sign(smallData, WalletApplet.SIGN_P1_DATA,true, true);
+    MessageDigest md = MessageDigest.getInstance("SHA-256", "BC");
+    response = cmdSet.sign(md.digest(data), WalletApplet.SIGN_P1_PRECOMPUTED_HASH,true, true);
     assertEquals(0x9000, response.getSW());
     byte[] sig = secureChannel.decryptAPDU(response.getData());
     byte[] keyData = extractPublicKey(sig);
     sig = extractSignature(sig);
     assertEquals((SecureChannel.SC_KEY_LENGTH * 2 / 8) + 1, keyData.length);
+    signature.update(data);
+    assertTrue(signature.verify(sig));
 
+    // Correctly sign 1 block (P2: 0x81)
+    response = cmdSet.sign(smallData, WalletApplet.SIGN_P1_DATA,true, true);
+    assertEquals(0x9000, response.getSW());
+    sig = extractSignature(secureChannel.decryptAPDU(response.getData()));
     signature.update(smallData);
     assertTrue(signature.verify(sig));
 
@@ -469,14 +477,6 @@ public class WalletAppletTest {
     signature.update(data);
     signature.update(smallData);
     assertTrue(signature.verify(sig));
-
-    MessageDigest md = MessageDigest.getInstance("SHA-256", "BC");
-    response = cmdSet.sign(md.digest(data), WalletApplet.SIGN_P1_PRECOMPUTED_HASH,true, true);
-    assertEquals(0x9000, response.getSW());
-    sig = extractSignature(secureChannel.decryptAPDU(response.getData()));
-    signature.update(data);
-    assertTrue(signature.verify(sig));
-
   }
 
   @Test