Add extra arg to AddWord() and add variant of Copy()

1 files changed, 10 insertions, 4 deletions

diff --git a/crypto/src/math/ec/Nat.cs b/crypto/src/math/ec/Nat.cs
index a5a496fad..9d2290ba7 100644
--- a/crypto/src/math/ec/Nat.cs
+++ b/crypto/src/math/ec/Nat.cs
@@ -69,10 +69,11 @@ namespace Org.BouncyCastle.Math.EC
             return (uint)c;
         }
 
-        public static uint AddWord(int len, uint x, uint[] z)
+        public static uint AddWord(int len, uint x, uint[] z, int zOff)
         {
-            ulong c = (ulong)x + z[0];
-            z[0] = (uint)c;
+            Debug.Assert(zOff < len);
+            ulong c = (ulong)x + z[zOff + 0];
+            z[zOff + 0] = (uint)c;
             c >>= 32;
             return c == 0 ? 0 : Inc(len, z, 1);
         }
@@ -80,13 +81,18 @@ namespace Org.BouncyCastle.Math.EC
         public static uint AddWordExt(int len, uint x, uint[] zz, int zzOff)
         {
             int extLen = len << 1;
-            Debug.Assert(zzOff <= (extLen - 1));
+            Debug.Assert(zzOff < extLen);
             ulong c = (ulong)x + zz[zzOff];
             zz[zzOff] = (uint)c;
             c >>= 32;
             return c == 0 ? 0 : Inc(extLen, zz, zzOff + 1);
         }
 
+        public static void Copy(int len, uint[] x, uint[] z)
+        {
+            Array.Copy(x, 0, z, 0, len);
+        }
+
         public static uint[] Copy(int len, uint[] x)
         {
             uint[] z = new uint[len];