replace Mayo.GF16Utils.inverseF with GF16.inv

Author: gefeili

core/src/main/java/org/bouncycastle/pqc/crypto/mayo/GF16Utils.java

@@ -208,19 +208,6 @@ static void mulAddMUpperTriangularMatXMatTrans(int mVecLimbs, long[] bsMat, byte
         }
     }
 
-    /**
-     * Computes the multiplicative inverse in GF(16) for a GF(16) element.
-     */
-    static byte inverseF(int a)
-    {
-        // In GF(16), the inverse can be computed via exponentiation.
-        int a2 = GF16.mul(a, a);
-        int a4 = GF16.mul(a2, a2);
-        int a8 = GF16.mul(a4, a4);
-        int a6 = GF16.mul(a2, a4);
-        return (byte)GF16.mul(a8, a6);
-    }
-
     /**
      * Performs a GF(16) carryless multiplication of a nibble (lower 4 bits of a)
      * with a 64-bit word b, then reduces modulo the polynomial x⁴ + x + 1 on each byte.

core/src/main/java/org/bouncycastle/pqc/crypto/mayo/MayoSigner.java

@@ -762,7 +762,7 @@ void ef(byte[] A, int nrows, int ncols)
             }
 
             // Multiply the pivot row by the inverse of the pivot element.
-            vecMulAddU64(rowLen, pivotRow, GF16Utils.inverseF(pivot), pivotRow2);
+            vecMulAddU64(rowLen, pivotRow, GF16.inv((byte)pivot), pivotRow2);
 
             // Conditionally write the pivot row back into the correct row (if pivot is nonzero).
             for (int row = lowerBound, rowRowLen = lowerBound * rowLen; row <= upperBound; row++, rowRowLen += rowLen)

core/src/main/java/org/bouncycastle/util/GF16.java

@@ -65,9 +65,17 @@ public static int mul(int a, int b)
         return MT4B[a << 4 | b];
     }
 
+    /**
+     * Computes the multiplicative inverse in GF(16) for a GF(16) element.
+     */
     public static byte inv(byte a)
     {
         return INV4B[a & 0xF];
+//        int a2 = GF16.mul(a, a);
+//        int a4 = GF16.mul(a2, a2);
+//        int a8 = GF16.mul(a4, a4);
+//        int a6 = GF16.mul(a2, a4);
+//        return (byte)GF16.mul(a8, a6);
     }
 
     /**