Fix final step of reduce()

1 files changed, 9 insertions, 10 deletions

diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
index 94bbef69..eecba2f2 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
@@ -116,27 +116,26 @@ public class SecP256R1Field
         cc >>= 32;
 
         int c = (int)cc;
-        if (c > 0)
+        if (c < 0)
         {
             do
             {
+                c += Nat256.add(z, P, z);
+            }
+            while (c < 0);
+        }
+        else
+        {
+            while (c > 0)
+            {
                 c += Nat256.sub(z, P, z);
             }
-            while (c != 0);
 
             if (z[7] == P7 && Nat256.gte(z, P))
             {
                 Nat256.sub(z, P, z);
             }
         }
-        else if (c < 0)
-        {
-            do
-            {
-                c += Nat256.add(z, P, z);
-            }
-            while (c != 0);
-        }
     }
 
     public static void square(int[] x, int[] z)