Class EllipticCurve

• java.lang.Object
• • java.security.spec.EllipticCurve

public class EllipticCurve
extends Object

This immutable class holds the necessary values needed to represent an elliptic curve.

Since:

1.5

See Also:

ECField, ECFieldFp, ECFieldF2m

Constructors

EllipticCurve

public EllipticCurve(ECField field,
                     BigInteger a,
                     BigInteger b)

Creates an elliptic curve with the specified elliptic field field and the coefficients a and b.

Parameters:

field - the finite field that this elliptic curve is over.

a - the first coefficient of this elliptic curve.

b - the second coefficient of this elliptic curve.

Throws:

NullPointerException - if field, a, or b is null.

IllegalArgumentException - if a or b is not null and not in field.

EllipticCurve

public EllipticCurve(ECField field,
                     BigInteger a,
                     BigInteger b,
                     byte[] seed)

Creates an elliptic curve with the specified elliptic field field, the coefficients a and b, and the seed used for curve generation.

Parameters:

field - the finite field that this elliptic curve is over.

a - the first coefficient of this elliptic curve.

b - the second coefficient of this elliptic curve.

seed - the bytes used during curve generation for later validation. Contents of this array are copied to protect against subsequent modification.

Throws:

NullPointerException - if field, a, or b is null.

IllegalArgumentException - if a or b is not null and not in field.

Methods

getField

public ECField getField()

Returns the finite field field that this elliptic curve is over.

Returns:

the field field that this curve is over.

getA

public BigInteger getA()

Returns the first coefficient a of the elliptic curve.

Returns:

the first coefficient a.

getB

public BigInteger getB()

Returns the second coefficient b of the elliptic curve.

Returns:

the second coefficient b.

getSeed

public byte[] getSeed()

Returns the seeding bytes seed used during curve generation. May be null if not specified.

Returns:

the seeding bytes seed. A new array is returned each time this method is called.

equals

public boolean equals(Object obj)

Compares this elliptic curve for equality with the specified object.

Overrides:

equals in class Object

Parameters:

obj - the object to be compared.

Returns:

true if obj is an instance of EllipticCurve and the field, A, and B match, false otherwise.

See Also:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Returns a hash code value for this elliptic curve.

Overrides:

hashCode in class Object

Returns:

a hash code value computed from the hash codes of the field, A, and B, as follows:

(field.hashCode() << 6) + (a.hashCode() << 4) + (b.hashCode() << 2)

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)