Refactor reduction methods and change scope of PExt fields

7 files changed, 92 insertions, 103 deletions

diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192K1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192K1Field.java
index dcb8e0fb..e310529d 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192K1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192K1Field.java
@@ -6,9 +6,9 @@ public class SecP192K1Field
 {
     // 2^192 - 2^32 - 2^12 - 2^8 - 2^7 - 2^6 - 2^3 - 1
     static final int[] P = new int[]{ 0xFFFFEE37, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
-    private static final int P5 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x013C4FD1, 0x00002392, 0x00000001, 0x00000000, 0x00000000,
+    static final int[] PExt = new int[]{ 0x013C4FD1, 0x00002392, 0x00000001, 0x00000000, 0x00000000,
         0x00000000, 0xFFFFDC6E, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int P5 = 0xFFFFFFFF;
     private static final int PExt11 = 0xFFFFFFFF;
     private static final long PInv = 0x00000001000011C9L;
     private static final int PInv33 = 0x11C9;
@@ -85,8 +85,8 @@ public class SecP192K1Field
 
     public static void reduce(int[] xx, int[] z)
     {
-        long c = Nat192.mul33Add(PInv33, xx, 6, xx, 0, z, 0);
-        c = Nat192.mul33DWordAdd(PInv33, c, z, 0);
+        long cc = Nat192.mul33Add(PInv33, xx, 6, xx, 0, z, 0);
+        int c = Nat192.mul33DWordAdd(PInv33, cc, z, 0);
 
         // assert c == 0L || c == 1L;
 
@@ -98,11 +98,8 @@ public class SecP192K1Field
 
     public static void reduce32(int x, int[] z)
     {
-        int c = Nat192.mul33WordAdd(PInv33, x, z, 0);
-
-        // assert c == 0L || c == 1L;
-
-        if (c != 0 || (z[5] == P5 && Nat192.gte(z, P)))
+        if ((x != 0 && Nat192.mul33WordAdd(PInv33, x, z, 0) != 0)
+            || (z[5] == P5 && Nat192.gte(z, P)))
         {
             Nat192.addDWord(PInv, z, 0);
         }
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192R1Field.java
index b7e11471..7f026009 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP192R1Field.java
@@ -8,9 +8,9 @@ public class SecP192R1Field
 
     // 2^192 - 2^64 - 1
     static final int[] P = new int[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
-    private static final int P5 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000002, 0x00000000, 0x00000001,
+    static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000002, 0x00000000, 0x00000001,
         0x00000000, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int P5 = 0xFFFFFFFF;
     private static final int PExt11 = 0xFFFFFFFF;
 
     public static void add(int[] x, int[] y, int[] z)
@@ -119,22 +119,13 @@ public class SecP192R1Field
         z[5] = (int)cc;
         cc >>= 32;
 
-        int c = (int)cc;
-        while (c > 0)
-        {
-            c += Nat192.sub(z, P, z);
-        }
-
-        if (z[5] == P5 && Nat192.gte(z, P))
-        {
-            Nat192.sub(z, P, z);
-        }
+        reduce32((int)cc, z);
     }
 
     public static void reduce32(int x, int[] z)
     {
-        int c = Nat192.addWord(x, z, 0) + Nat192.addWord(x, z, 2);
-        if (c != 0 || (z[5] == P5 && Nat192.gte(z, P)))
+        if ((x != 0 && (Nat192.addWord(x, z, 0) + Nat192.addWord(x, z, 2) != 0))
+            || (z[5] == P5 && Nat192.gte(z, P)))
         {
             Nat192.sub(z, P, z);
         }
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224K1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224K1Field.java
index 70895d51..4dc9e121 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224K1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224K1Field.java
@@ -7,9 +7,9 @@ public class SecP224K1Field
     // 2^224 - 2^32 - 2^12 - 2^11 - 2^9 - 2^7 - 2^4 - 2 - 1
     static final int[] P = new int[]{ 0xFFFFE56D, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
         0xFFFFFFFF };
-    private static final int P6 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x02C23069, 0x00003526, 0x00000001, 0x00000000, 0x00000000,
+    static final int[] PExt = new int[]{ 0x02C23069, 0x00003526, 0x00000001, 0x00000000, 0x00000000,
         0x00000000, 0x00000000, 0xFFFFCADA, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int P6 = 0xFFFFFFFF;
     private static final int PExt13 = 0xFFFFFFFF;
     private static final long PInv = 0x0000000100001A93L; 
     private static final int PInv33 = 0x1A93;
@@ -86,8 +86,8 @@ public class SecP224K1Field
 
     public static void reduce(int[] xx, int[] z)
     {
-        long c = Nat224.mul33Add(PInv33, xx, 7, xx, 0, z, 0);
-        c = Nat224.mul33DWordAdd(PInv33, c, z, 0);
+        long cc = Nat224.mul33Add(PInv33, xx, 7, xx, 0, z, 0);
+        int c = Nat224.mul33DWordAdd(PInv33, cc, z, 0);
 
         // assert c == 0L || c == 1L;
 
@@ -99,11 +99,8 @@ public class SecP224K1Field
 
     public static void reduce32(int x, int[] z)
     {
-        int c = Nat224.mul33WordAdd(PInv33, x, z, 0);
-
-        // assert c == 0L || c == 1L;
-
-        if (c != 0 || (z[6] == P6 && Nat224.gte(z, P)))
+        if ((x != 0 && Nat224.mul33WordAdd(PInv33, x, z, 0) != 0)
+            || (z[6] == P6 && Nat224.gte(z, P)))
         {
             Nat224.addDWord(PInv, z, 0);
         }
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224R1Field.java
index 72a1dc52..ef851d8f 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP224R1Field.java
@@ -8,9 +8,9 @@ public class SecP224R1Field
 
     // 2^224 - 2^96 + 1
     static final int[] P = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
-    private static final int P6 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF,
+    static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF,
         0xFFFFFFFF, 0x00000000, 0x00000002, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int P6 = 0xFFFFFFFF;
     private static final int PExt13 = 0xFFFFFFFF;
 
     public static void add(int[] x, int[] y, int[] z)
@@ -116,7 +116,7 @@ public class SecP224R1Field
         cc >>= 32;
 
         int c = (int)cc;
-        if (c > 0)
+        if (c >= 0)
         {
             reduce32(c, z);
         }
@@ -131,8 +131,8 @@ public class SecP224R1Field
 
     public static void reduce32(int x, int[] z)
     {
-        int c = Nat224.subWord(x, z, 0) + Nat224.addWord(x, z, 3);
-        if (c != 0 || (z[6] == P6 && Nat224.gte(z, P)))
+        if ((x != 0 && (Nat224.subWord(x, z, 0) + Nat224.addWord(x, z, 3) != 0))
+            || (z[6] == P6 && Nat224.gte(z, P)))
         {
             Nat224.sub(z, P, z);
         }
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
index 4f16c5c6..b4c47fbe 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256K1Field.java
@@ -8,7 +8,7 @@ public class SecP256K1Field
     static final int[] P = new int[]{ 0xFFFFFC2F, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
         0xFFFFFFFF, 0xFFFFFFFF };
     private static final int P7 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x000E90A1, 0x000007A2, 0x00000001, 0x00000000, 0x00000000,
+    static final int[] PExt = new int[]{ 0x000E90A1, 0x000007A2, 0x00000001, 0x00000000, 0x00000000,
         0x00000000, 0x00000000, 0x00000000, 0xFFFFF85E, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
         0xFFFFFFFF, 0xFFFFFFFF };
     private static final int PExt15 = 0xFFFFFFFF;
@@ -87,8 +87,8 @@ public class SecP256K1Field
 
     public static void reduce(int[] xx, int[] z)
     {
-        long c = Nat256.mul33Add(PInv33, xx, 8, xx, 0, z, 0);
-        c = Nat256.mul33DWordAdd(PInv33, c, z, 0);
+        long cc = Nat256.mul33Add(PInv33, xx, 8, xx, 0, z, 0);
+        int c = Nat256.mul33DWordAdd(PInv33, cc, z, 0);
 
         // assert c == 0L || c == 1L;
 
@@ -100,11 +100,8 @@ public class SecP256K1Field
 
     public static void reduce32(int x, int[] z)
     {
-        int c = Nat256.mul33WordAdd(PInv33, x, z, 0);
-
-        // assert c == 0L || c == 1L;
-
-        if (c != 0 || (z[7] == P7 && Nat256.gte(z, P)))
+        if ((x != 0 && Nat256.mul33WordAdd(PInv33, x, z, 0) != 0)
+            || (z[7] == P7 && Nat256.gte(z, P)))
         {
             Nat256.addDWord(PInv, z, 0);
         }
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 d3baceda..8315935c 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
@@ -9,12 +9,12 @@ public class SecP256R1Field
     // 2^256 - 2^224 + 2^192 + 2^96 - 1
     static final int[] P = new int[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000, 0x00000000,
         0x00000001, 0xFFFFFFFF };
+    static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF,
+        0xFFFFFFFF, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0x00000001, 0xFFFFFFFE,
+        0x00000002, 0xFFFFFFFE };
     private static final int[] _2P = new int[]{ 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000001, 0x00000000, 0x00000000,
         0x00000002, 0xFFFFFFFE, 0x00000001 };
     private static final int P7 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF,
-        0xFFFFFFFF, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0x00000001, 0xFFFFFFFE,
-        0x00000002, 0xFFFFFFFE };
 
     public static void add(int[] x, int[] y, int[] z)
     {
@@ -126,7 +126,7 @@ public class SecP256R1Field
         cc >>= 32;
 
         int c = (int)cc;
-        if (c > 0)
+        if (c >= 0)
         {
             reduce32(c, z);
         }
@@ -145,33 +145,39 @@ public class SecP256R1Field
 
     public static void reduce32(int x, int[] z)
     {
-        long xx08 = x & M;
-
         long cc = 0;
-        cc += (z[0] & M) + xx08;
-        z[0] = (int)cc;
-        cc >>= 32;
-        cc += (z[1] & M);
-        z[1] = (int)cc;
-        cc >>= 32;
-        cc += (z[2] & M);
-        z[2] = (int)cc;
-        cc >>= 32;
-        cc += (z[3] & M) - xx08;
-        z[3] = (int)cc;
-        cc >>= 32;
-        cc += (z[4] & M);
-        z[4] = (int)cc;
-        cc >>= 32;
-        cc += (z[5] & M);
-        z[5] = (int)cc;
-        cc >>= 32;
-        cc += (z[6] & M) - xx08;
-        z[6] = (int)cc;
-        cc >>= 32;
-        cc += (z[7] & M) + xx08;
-        z[7] = (int)cc;
-        cc >>= 32;
+
+        if (x != 0)
+        {
+            long xx08 = x & M;
+
+            cc += (z[0] & M) + xx08;
+            z[0] = (int)cc;
+            cc >>= 32;
+            cc += (z[1] & M);
+            z[1] = (int)cc;
+            cc >>= 32;
+            cc += (z[2] & M);
+            z[2] = (int)cc;
+            cc >>= 32;
+            cc += (z[3] & M) - xx08;
+            z[3] = (int)cc;
+            cc >>= 32;
+            cc += (z[4] & M);
+            z[4] = (int)cc;
+            cc >>= 32;
+            cc += (z[5] & M);
+            z[5] = (int)cc;
+            cc >>= 32;
+            cc += (z[6] & M) - xx08;
+            z[6] = (int)cc;
+            cc >>= 32;
+            cc += (z[7] & M) + xx08;
+            z[7] = (int)cc;
+            cc >>= 32;
+
+//          assert cc == 0 || cc == 1;
+        }
 
         if (cc != 0 || (z[7] == P7 && Nat256.gte(z, P)))
         {
diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP384R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP384R1Field.java
index d7d0d50e..b4df7ec0 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP384R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP384R1Field.java
@@ -11,10 +11,10 @@ public class SecP384R1Field
     // 2^384 - 2^128 - 2^96 + 2^32 - 1
     static final int[] P = new int[]{ 0xFFFFFFFF, 0x00000000, 0x00000000, 0xFFFFFFFF, 0xFFFFFFFE, 0xFFFFFFFF,
         0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
-    private static final int P11 = 0xFFFFFFFF;
-    private static final int[] PExt = new int[]{ 0x00000001, 0xFFFFFFFE, 0x00000000, 0x00000002, 0x00000000, 0xFFFFFFFE,
+    static final int[] PExt = new int[]{ 0x00000001, 0xFFFFFFFE, 0x00000000, 0x00000002, 0x00000000, 0xFFFFFFFE,
         0x00000000, 0x00000002, 0x00000001, 0x00000000, 0x00000000, 0x00000000, 0xFFFFFFFE, 0x00000001, 0x00000000,
         0xFFFFFFFE, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+    private static final int P11 = 0xFFFFFFFF;
     private static final int PExt23 = 0xFFFFFFFF;
 
     public static void add(int[] x, int[] y, int[] z)
@@ -132,7 +132,7 @@ public class SecP384R1Field
         cc >>= 32;
 
         int c = (int)cc;
-        if (c > 0)
+        if (c >= 0)
         {
             reduce32(c, z);
         }
@@ -147,34 +147,35 @@ public class SecP384R1Field
 
     public static void reduce32(int x, int[] z)
     {
-        long xx12 = x & M;
-
         long cc = 0;
-        cc += (z[0] & M) + xx12;
-        z[0] = (int)cc;
-        cc >>= 32;
-        cc += (z[1] & M) - xx12;
-        z[1] = (int)cc;
-        cc >>= 32;
-        cc += (z[2] & M);
-        z[2] = (int)cc;
-        cc >>= 32;
-        cc += (z[3] & M) + xx12;
-        z[3] = (int)cc;
-        cc >>= 32;
-        cc += (z[4] & M) + xx12;
-        z[4] = (int)cc;
-        cc >>= 32;
-
-//        assert cc >= 0;
+        
+        if (x != 0)
+        {
+            long xx12 = x & M;
+    
+            cc += (z[0] & M) + xx12;
+            z[0] = (int)cc;
+            cc >>= 32;
+            cc += (z[1] & M) - xx12;
+            z[1] = (int)cc;
+            cc >>= 32;
+            cc += (z[2] & M);
+            z[2] = (int)cc;
+            cc >>= 32;
+            cc += (z[3] & M) + xx12;
+            z[3] = (int)cc;
+            cc >>= 32;
+            cc += (z[4] & M) + xx12;
+            z[4] = (int)cc;
+            cc >>= 32;
+
+//            assert cc == 0 || cc == 1;
+        }
 
-        if (cc > 0)
+        if ((cc != 0 && Nat.inc(12, z, 5) != 0)
+            || (z[11] == P11 && Nat.gte(12, z, P)))
         {
-            int c = Nat.addWord(12, (int)cc, z, 5);
-            if (c != 0 || (z[11] == P11 && Nat.gte(12, z, P)))
-            {
-                Nat.sub(12, z, P, z);
-            }
+            Nat.sub(12, z, P, z);
         }
     }