
Java™ Platform Standard Ed. 6 

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java.lang.Object java.security.spec.ECFieldF2m
public class ECFieldF2m
This immutable class defines an elliptic curve (EC) characteristic 2 finite field.
ECField
Constructor Summary  

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

ECFieldF2m(int m,
BigInteger rp)
Creates an elliptic curve characteristic 2 finite field which has 2^ m elements with
polynomial basis. 

ECFieldF2m(int m,
int[] ks)
Creates an elliptic curve characteristic 2 finite field which has 2^ m elements with
polynomial basis. 
Method Summary  

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 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. 
Methods inherited from class java.lang.Object 

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

public ECFieldF2m(int m)
m
elements with normal basis.
m
 with 2^m
being the number of elements.
IllegalArgumentException
 if m
is not positive.public ECFieldF2m(int m, BigInteger rp)
m
elements with
polynomial basis.
The reduction polynomial for this field is based
on rp
whose ith bit correspondes 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).
m
 with 2^m
being the number of elements.rp
 the BigInteger whose ith bit corresponds to
the ith coefficient of the reduction polynomial.
NullPointerException
 if rp
is null.
IllegalArgumentException
 if m
is not positive, or rp
does not represent
a valid reduction polynomial.public ECFieldF2m(int m, int[] ks)
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.
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.
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.Method Detail 

public int getFieldSize()
m
for this characteristic 2 finite field.
getFieldSize
in interface ECField
public int getM()
m
of this characteristic
2 finite field.
m
with 2^m
being the
number of elements.public BigInteger getReductionPolynomial()
public int[] getMidTermsOfReductionPolynomial()
public boolean equals(Object obj)
equals
in class Object
obj
 the object to be compared.
obj
is an instance
of ECFieldF2m and both m
and the reduction
polynomial match, false otherwise.Object.hashCode()
,
Hashtable
public int hashCode()
hashCode
in class Object
Object.equals(java.lang.Object)
,
Hashtable

Java™ Platform Standard Ed. 6 

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