程序包 java.security.spec

类 ECFieldF2m

java.lang.Object

java.security.spec.ECFieldF2m

所有已实现的接口:

ECField

public class ECFieldF2m
extends Object
implements ECField

This immutable class defines an elliptic curve (EC) characteristic 2 finite field.

从以下版本开始:

1.5

另请参阅:

ECField

构造器概要

构造器

构造器	说明
ECFieldF2m(int m)	Creates an elliptic curve characteristic 2 finite field which has 2^m elements with normal basis.
ECFieldF2m(int m, int[] ks)	Creates an elliptic curve characteristic 2 finite field which has 2^m elements with polynomial basis.
ECFieldF2m(int m, BigInteger rp)	Creates an elliptic curve characteristic 2 finite field which has 2^m elements with polynomial basis.

方法概要

限定符和类型	方法	说明
boolean	equals(Object obj)	Compares this finite field for equality with the specified object.
int	getFieldSize()	Returns the field size in bits which is m for this characteristic 2 finite field.
int	getM()	Returns the value m of this characteristic 2 finite field.
int[]	getMidTermsOfReductionPolynomial()	Returns an integer array which contains the order of the middle term(s) of the reduction polynomial for polynomial basis or null for normal basis.
BigInteger	getReductionPolynomial()	Returns a BigInteger whose i-th bit corresponds to the i-th coefficient of the reduction polynomial for polynomial basis or null for normal basis.
int	hashCode()	Returns a hash code value for this characteristic 2 finite field.

从类继承的方法 java.lang.Object

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

构造器详细资料

ECFieldF2m

public ECFieldF2m(int m)

Creates an elliptic curve characteristic 2 finite field which has 2^m elements with normal basis.

参数:

m - with 2^m being the number of elements.

抛出:

IllegalArgumentException - if m is not positive.

ECFieldF2m

public ECFieldF2m(int m,
                  BigInteger rp)

Creates an elliptic curve characteristic 2 finite field which has 2^m elements with polynomial basis. The reduction polynomial for this field is based on rp whose i-th bit corresponds to the i-th coefficient of the reduction polynomial.

Note: A valid reduction polynomial is either a trinomial (X^m + X^k + 1 with m > k >= 1) or a pentanomial (X^m + X^k3 + X^k2 + X^k1 + 1 with m > k3 > k2 > k1 >= 1).

参数:

m - with 2^m being the number of elements.

rp - the BigInteger whose i-th bit corresponds to the i-th coefficient of the reduction polynomial.

抛出:

NullPointerException - if rp is null.

IllegalArgumentException - if m is not positive, or rp does not represent a valid reduction polynomial.

ECFieldF2m

public ECFieldF2m(int m,
                  int[] ks)

Creates an elliptic curve characteristic 2 finite field which has 2^m elements with polynomial basis. The reduction polynomial for this field is based on ks whose content contains the order of the middle term(s) of the reduction polynomial. Note: A valid reduction polynomial is either a trinomial (X^m + X^k + 1 with m > k >= 1) or a pentanomial (X^m + X^k3 + X^k2 + X^k1 + 1 with m > k3 > k2 > k1 >= 1), so ks should have length 1 or 3.

参数:

m - with 2^m being the number of elements.

ks - the order of the middle term(s) of the reduction polynomial. Contents of this array are copied to protect against subsequent modification.

抛出:

NullPointerException - if ks is null.

IllegalArgumentException - ifm is not positive, or the length of ks is neither 1 nor 3, or values in ks are not between m-1 and 1 (inclusive) and in descending order.

方法详细资料

getFieldSize

public int getFieldSize()

Returns the field size in bits which is m for this characteristic 2 finite field.

指定者:

getFieldSize 在接口中 ECField

返回:

the field size in bits.

getM

public int getM()

Returns the value m of this characteristic 2 finite field.

返回:

m with 2^m being the number of elements.

getReductionPolynomial

public BigInteger getReductionPolynomial()

Returns a BigInteger whose i-th bit corresponds to the i-th coefficient of the reduction polynomial for polynomial basis or null for normal basis.

返回:

a BigInteger whose i-th bit corresponds to the i-th coefficient of the reduction polynomial for polynomial basis or null for normal basis.

getMidTermsOfReductionPolynomial

public int[] getMidTermsOfReductionPolynomial()

Returns an integer array which contains the order of the middle term(s) of the reduction polynomial for polynomial basis or null for normal basis.

返回:

an integer array which contains the order of the middle term(s) of the reduction polynomial for polynomial basis or null for normal basis. A new array is returned each time this method is called.

equals

public boolean equals(Object obj)

Compares this finite field for equality with the specified object.

覆盖:

equals 在类中 Object

参数:

obj - the object to be compared.

返回:

true if obj is an instance of ECFieldF2m and both m and the reduction polynomial match, false otherwise.

另请参阅:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Returns a hash code value for this characteristic 2 finite field.

覆盖:

hashCode 在类中 Object

返回:

a hash code value.

另请参阅:

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