Check for negative r, s

Refactor local variables

1 files changed, 24 insertions, 12 deletions

diff --git a/core/src/main/java/org/bouncycastle/crypto/signers/DSTU4145Signer.java b/core/src/main/java/org/bouncycastle/crypto/signers/DSTU4145Signer.java
index ee3cf34d..2979a5db 100644
--- a/core/src/main/java/org/bouncycastle/crypto/signers/DSTU4145Signer.java
+++ b/core/src/main/java/org/bouncycastle/crypto/signers/DSTU4145Signer.java
@@ -5,6 +5,7 @@ import java.security.SecureRandom;
 
 import org.bouncycastle.crypto.CipherParameters;
 import org.bouncycastle.crypto.DSA;
+import org.bouncycastle.crypto.params.ECDomainParameters;
 import org.bouncycastle.crypto.params.ECKeyParameters;
 import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
 import org.bouncycastle.crypto.params.ECPublicKeyParameters;
@@ -56,12 +57,17 @@ public class DSTU4145Signer
 
     public BigInteger[] generateSignature(byte[] message)
     {
-        ECFieldElement h = hash2FieldElement(key.getParameters().getCurve(), message);
+        ECDomainParameters parameters = key.getParameters();
+
+        ECCurve curve = parameters.getCurve();
+
+        ECFieldElement h = hash2FieldElement(curve, message);
         if (h.isZero())
         {
-            h = key.getParameters().getCurve().fromBigInteger(ONE);
+            h = curve.fromBigInteger(ONE);
         }
 
+        BigInteger n = parameters.getN();
         BigInteger e, r, s;
         ECFieldElement Fe, y;
 
@@ -71,17 +77,17 @@ public class DSTU4145Signer
             {
                 do
                 {
-                    e = generateRandomInteger(key.getParameters().getN(), random);
-                    Fe = key.getParameters().getG().multiply(e).normalize().getAffineXCoord();
+                    e = generateRandomInteger(n, random);
+                    Fe = parameters.getG().multiply(e).normalize().getAffineXCoord();
                 }
                 while (Fe.isZero());
 
                 y = h.multiply(Fe);
-                r = fieldElement2Integer(key.getParameters().getN(), y);
+                r = fieldElement2Integer(n, y);
             }
             while (r.signum() == 0);
 
-            s = r.multiply(((ECPrivateKeyParameters)key).getD()).add(e).mod(key.getParameters().getN());
+            s = r.multiply(((ECPrivateKeyParameters)key).getD()).add(e).mod(n);
         }
         while (s.signum() == 0);
 
@@ -90,22 +96,28 @@ public class DSTU4145Signer
 
     public boolean verifySignature(byte[] message, BigInteger r, BigInteger s)
     {
-        if (r.signum() == 0 || s.signum() == 0)
+        if (r.signum() <= 0 || s.signum() <= 0)
         {
             return false;
         }
-        if (r.compareTo(key.getParameters().getN()) >= 0 || s.compareTo(key.getParameters().getN()) >= 0)
+
+        ECDomainParameters parameters = key.getParameters();
+
+        BigInteger n = parameters.getN();
+        if (r.compareTo(n) >= 0 || s.compareTo(n) >= 0)
         {
             return false;
         }
 
-        ECFieldElement h = hash2FieldElement(key.getParameters().getCurve(), message);
+        ECCurve curve = parameters.getCurve();
+
+        ECFieldElement h = hash2FieldElement(curve, message);
         if (h.isZero())
         {
-            h = key.getParameters().getCurve().fromBigInteger(ONE);
+            h = curve.fromBigInteger(ONE);
         }
 
-        ECPoint R = ECAlgorithms.sumOfTwoMultiplies(key.getParameters().getG(), s, ((ECPublicKeyParameters)key).getQ(), r).normalize();
+        ECPoint R = ECAlgorithms.sumOfTwoMultiplies(parameters.getG(), s, ((ECPublicKeyParameters)key).getQ(), r).normalize();
 
         // components must be bogus.
         if (R.isInfinity())
@@ -114,7 +126,7 @@ public class DSTU4145Signer
         }
 
         ECFieldElement y = h.multiply(R.getAffineXCoord());
-        return fieldElement2Integer(key.getParameters().getN(), y).compareTo(r) == 0;
+        return fieldElement2Integer(n, y).compareTo(r) == 0;
     }
 
     /**