Package org.bouncycastle.math.ec.custom.gm

Class SM9P256V1Field

  • public class SM9P256V1Field
extends java.lang.Object
    Prime-field arithmetic for the SM9 256-bit Barreto-Naehrig base field F_q (GM/T 0044.5-2016), used by the G1 curve SM9P256V1Curve.

    Unlike SM2P256V1Field (whose sparse prime admits a fast Solinas reduction and stores elements in the ordinary residue representation), the SM9 BN prime is a general 256-bit prime, so this field keeps elements in Montgomery form (a·R mod q, R = 2^256) and multiplies with a Montgomery (SOS) reduction. Fixed-limb Nat256 arithmetic makes the field operations constant time (no data-dependent branches beyond the standard conditional subtractions), unlike the variable-length BigInteger the generic ECCurve.Fp would use.

    The constants n0 = -q^-1 mod 2^32 and R^2 mod q are derived from q at class load (a micro-optimisation would inline them as int[] literals as SM2 does).

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static void add​(int[] x, int[] y, int[] z)  
      static int[] fromBigInteger​(java.math.BigInteger x)  
      static void inv​(int[] x, int[] z)  
      static boolean isZero​(int[] x)  
      static void multiply​(int[] x, int[] y, int[] z)  
      static void negate​(int[] x, int[] z)  
      static void square​(int[] x, int[] z)  
      static void squareN​(int[] x, int n, int[] z)  
      static void subtract​(int[] x, int[] y, int[] z)  
      static java.math.BigInteger toBigInteger​(int[] xMont)  
      static void twice​(int[] x, int[] z)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • add

        public static void add​(int[] x,
                       int[] y,
                       int[] z)

      • subtract

        public static void subtract​(int[] x,
                            int[] y,
                            int[] z)

      • negate

        public static void negate​(int[] x,
                          int[] z)

      • twice

        public static void twice​(int[] x,
                         int[] z)

      • multiply

        public static void multiply​(int[] x,
                            int[] y,
                            int[] z)

      • square

        public static void square​(int[] x,
                          int[] z)

      • squareN

        public static void squareN​(int[] x,
                           int n,
                           int[] z)

      • fromBigInteger

        public static int[] fromBigInteger​(java.math.BigInteger x)

      • toBigInteger

        public static java.math.BigInteger toBigInteger​(int[] xMont)

      • inv

        public static void inv​(int[] x,
                       int[] z)

      • isZero

        public static boolean isZero​(int[] x)