Class OwlCurve

java.lang.Object
org.bouncycastle.crypto.agreement.owl.OwlCurve
public class OwlCurve extends Object
A pre-computed elliptic curve over a prime field, in short-Weierstrass form for use during an Owl exchange.

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

See OwlCurves for convenient standard curves.

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

  • Constructor Details

    • OwlCurve

      public OwlCurve(BigInteger q, BigInteger a, BigInteger b, BigInteger n, BigInteger h, BigInteger g_x, BigInteger g_y)
      Constructs a new OwlCurve.

      In general, you should use one of the pre-approved curves from OwlCurves, 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.

      Parameters:
      q - The prime field modulus
      a - The curve coefficient a
      b - The curve coefficient b
      n - The order of the base point G
      h - The co-factor
      g_x - The x coordinate of the base point G
      g_y - The y coordinate of the base point G
      Throws:
      NullPointerException - if any argument is null
      IllegalArgumentException - if any of the above validations fail

  • Method Details

    • getCurve

      public ECCurve.AbstractFp getCurve()
      Get the elliptic curve
      Returns:
      The curve

    • getG

      public ECPoint getG()
      Get the base point G
      Returns:
      G

    • getA

      public BigInteger getA()
      Get the curve coefficient a
      Returns:
      a

    • getB

      public BigInteger getB()
      Get the curve coefficient b
      Returns:
      b

    • getN

      public BigInteger getN()
      Get n, the order of the base point
      Returns:
      n

    • getH

      public BigInteger getH()
      Get the co-factor h of the curve
      Returns:
      h

    • getQ

      public BigInteger getQ()
      Get the prime field modulus q of the curve
      Returns:
      q