org.bouncycastle.crypto.agreement.ecjpake

Class ECJPAKECurve

java.lang.Object

org.bouncycastle.crypto.agreement.ecjpake.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 and 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.

Method Summary

Modifier and Type	Method and Description
java.math.BigInteger	getA()
java.math.BigInteger	getB()
ECCurve.AbstractFp	getCurve()
ECPoint	getG()
java.math.BigInteger	getH()
java.math.BigInteger	getN()
java.math.BigInteger	getQ()

Methods inherited from class java.lang.Object

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

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

getCurve

public ECCurve.AbstractFp getCurve()

getG

public ECPoint getG()

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()