Added in API level 1

Summary: Ctors | Methods | Inherited Methods

ECFieldF2m

public class ECFieldF2m
extends Object implements ECField

java.lang.Object
↳	java.security.spec.ECFieldF2m

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

See also:

• ECField

Summary

Public constructors
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.

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 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.

Inherited methods
From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
From interface java.security.spec.ECField abstract int getFieldSize() Returns the field size in bits.

Public constructors

ECFieldF2m

Added in API level 1

public 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

Added in API level 1

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.

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.

ECFieldF2m

Added in API level 1

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).

Parameters
m	int: with 2^m being the number of elements.
rp	BigInteger: the BigInteger whose i-th bit corresponds to the i-th 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.

Public methods

equals

Added in API level 1

public 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

Added in API level 1

public 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

Added in API level 1

public int getM ()

Returns the value m of this characteristic 2 finite field.

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

getMidTermsOfReductionPolynomial

Added in API level 1

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.

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

Added in API level 1

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.

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

hashCode

Added in API level 1

public int hashCode ()

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

Returns
int	a hash code value.