org.bouncycastle.crypto.agreement.owl

Class OwlCurve

java.lang.Object

org.bouncycastle.crypto.agreement.owl.OwlCurve

public class OwlCurve
extends java.lang.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 Summary

Constructors

Constructor and Description
OwlCurve(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 OwlCurve.

Method Summary

Modifier and Type	Method and Description
java.math.BigInteger	getA() Get the curve coefficient a
java.math.BigInteger	getB() Get the curve coefficient b
ECCurve.AbstractFp	getCurve() Get the elliptic curve
ECPoint	getG() Get the base point G
java.math.BigInteger	getH() Get the co-factor h of the curve
java.math.BigInteger	getN() Get n, the order of the base point
java.math.BigInteger	getQ() Get the prime field modulus q of the curve

Methods inherited from class java.lang.Object

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

Constructor Detail

OwlCurve

public OwlCurve(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 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:

java.lang.NullPointerException - if any argument is null

java.lang.IllegalArgumentException - if any of the above validations fail

Method Detail

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 java.math.BigInteger getA()

Get the curve coefficient a

Returns:

a

getB

public java.math.BigInteger getB()

Get the curve coefficient b

Returns:

b

getN

public java.math.BigInteger getN()

Get n, the order of the base point

Returns:

n

getH

public java.math.BigInteger getH()

Get the co-factor h of the curve

Returns:

h

getQ

public java.math.BigInteger getQ()

Get the prime field modulus q of the curve

Returns:

q