ECFieldF2m
public
class
ECFieldF2m
extends Object
implements
ECField
java.lang.Object  
↳  java.security.spec.ECFieldF2m 
This immutable class defines an elliptic curve (EC) characteristic 2 finite field.
See also:
Summary
Public constructors  

ECFieldF2m(int m)
Creates an elliptic curve characteristic 2 finite
field which has 2^ 

ECFieldF2m(int m, BigInteger rp)
Creates an elliptic curve characteristic 2 finite
field which has 2^ 

ECFieldF2m(int m, int[] ks)
Creates an elliptic curve characteristic 2 finite
field which has 2^ 
Public methods  

boolean

equals(Object obj)
Compares this finite field for equality with the specified object. 
int

getFieldSize()
Returns the field size in bits which is 
int

getM()
Returns the value 
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 ith bit corresponds to the ith 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. 
Inherited methods  

Public constructors
ECFieldF2m
ECFieldF2m (int m)
Creates an elliptic curve characteristic 2 finite
field which has 2^m
elements with normal basis.
Parameters  

m 
int : with 2^m being the number of elements. 
Throws  

IllegalArgumentException 
if m
is not positive.

ECFieldF2m
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 ith bit corresponds to
the ith 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).
Parameters  

m 
int : with 2^m being the number of elements. 
rp 
BigInteger : the BigInteger whose ith bit corresponds to
the ith coefficient of the reduction polynomial. 
Throws  

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

ECFieldF2m
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.
Parameters  

m 
int : with 2^m being the number of elements. 
ks 
int : the order of the middle term(s) of the
reduction polynomial. Contents of this array are copied
to protect against subsequent modification. 
Throws  

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.

Public methods
equals
boolean equals (Object obj)
Compares this finite field for equality with the specified object.
Parameters  

obj 
Object : the object to be compared. 
Returns  

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

getFieldSize
int getFieldSize ()
Returns the field size in bits which is m
for this characteristic 2 finite field.
Returns  

int 
the field size in bits. 
getM
int getM ()
Returns the value m
of this characteristic
2 finite field.
Returns  

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

getMidTermsOfReductionPolynomial
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.
Returns  

int[] 
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. 
getReductionPolynomial
BigInteger getReductionPolynomial ()
Returns a BigInteger whose ith bit corresponds to the ith coefficient of the reduction polynomial for polynomial basis or null for normal basis.
Returns  

BigInteger 
a BigInteger whose ith bit corresponds to the ith coefficient of the reduction polynomial for polynomial basis or null for normal basis. 
hashCode
int hashCode ()
Returns a hash code value for this characteristic 2 finite field.
Returns  

int 
a hash code value. 