Class ECJPAKECurve


  • public class ECJPAKECurve
    extends java.lang.Object
    A pre-computed elliptic curve over a prime field, in short-Weierstrass form for use during an EC J-PAKE exchange.

    In general, J-PAKE can use any elliptic curve or prime order group that is suitable for public key cryptography.

    See ECJPAKECurves for convenient standard curves.

    NIST publishes many curves with different forms and levels of security.

    • Constructor Summary

      Constructors 
      Constructor Description
      ECJPAKECurve​(java.math.BigInteger q, java.math.BigInteger a, java.math.BigInteger b, java.math.BigInteger n, java.math.BigInteger h, java.math.BigInteger g_x, java.math.BigInteger g_y)
      Constructs a new ECJPAKECurve.
    • Constructor Detail

      • ECJPAKECurve

        public ECJPAKECurve​(java.math.BigInteger q,
                            java.math.BigInteger a,
                            java.math.BigInteger b,
                            java.math.BigInteger n,
                            java.math.BigInteger h,
                            java.math.BigInteger g_x,
                            java.math.BigInteger g_y)
        Constructs a new ECJPAKECurve.

        In general, you should use one of the pre-approved curves from ECJPAKECurves, rather than manually constructing one.

        The following basic checks are performed:

        • q must be prime
        • n must be prime
        • The curve must not be singular i.e. the discriminant is equal to 0 mod q
        • G must lie on the curve
        • n*h must equal the order of the curve
        • a must be in [0, q-1]
        • b must be in [0, q-1]

        The prime checks are performed using BigInteger.isProbablePrime(int), and are therefore subject to the same probability guarantees.

        These checks prevent trivial mistakes. However, due to the small uncertainties if p and q are not prime, advanced attacks are not prevented. Use it at your own risk.

        Throws:
        java.lang.NullPointerException - if any argument is null
        java.lang.IllegalArgumentException - if any of the above validations fail
    • Method Detail

      • getA

        public java.math.BigInteger getA()
      • getB

        public java.math.BigInteger getB()
      • getN

        public java.math.BigInteger getN()
      • getH

        public java.math.BigInteger getH()
      • getQ

        public java.math.BigInteger getQ()