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| java.lang.Object
 java.security.spec.ECFieldF2m
| ECFieldF2m | | public class ECFieldF2m implements ECField(Code) | | This immutable class defines an elliptic curve (EC)
characteristic 2 finite field.
See Also: ECField
author:
Valerie Peng
version:
1.10, 05/05/07
since:
1.5 |
| Constructor Summary | |
| public | ECFieldF2m(int m)
Creates an elliptic curve characteristic 2 finite
field which has 2^m elements with normal basis. | | 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 correspondes 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). | | public | ECFieldF2m(int m, int[] ks)
Creates an elliptic curve characteristic 2 finite
field which has 2^m elements with
polynomial basis. |
| Method Summary | |
| public boolean | equals(Object obj)
Compares this finite field for equality with the
specified object. | | public int | getFieldSize()
Returns the field size in bits which is m
for this characteristic 2 finite field. | | public int | getM()
Returns the value m of this characteristic
2 finite field. | | 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.
an integer array which contains the order of the middle term(s) of the reduction polynomial for polynomial basis or null for normal basis. | | 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. | | public int | hashCode()
Returns a hash code value for this characteristic 2
finite field. |
| ECFieldF2m | | public ECFieldF2m(int m)(Code) | | Creates an elliptic curve characteristic 2 finite
field which has 2^m elements with normal basis.
Parameters:
m - with 2^m being the number of elements.
exception:
IllegalArgumentException - if mis not positive. |
| ECFieldF2m | | public ECFieldF2m(int m, BigInteger rp)(Code) | | 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 correspondes 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 - with 2^m being the number of elements.
Parameters:
rp - the BigInteger whose i-th bit corresponds tothe i-th coefficient of the reduction polynomial.
exception:
NullPointerException - if rp is null.
exception:
IllegalArgumentException - if m is not positive, or rp does not represent a valid reduction polynomial. |
| ECFieldF2m | | public ECFieldF2m(int m, int[] ks)(Code) | | 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 - with 2^m being the number of elements.
Parameters:
ks - the order of the middle term(s) of thereduction polynomial. Contents of this array are copied to protect against subsequent modification.
exception:
NullPointerException - if ks is null.
exception:
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. |
| equals | | public boolean equals(Object obj)(Code) | | Compares this finite field for equality with the
specified object.
Parameters:
obj - the object to be compared. true if obj is an instanceof ECFieldF2m and both m and the reduction polynomial match, false otherwise. |
| getFieldSize | | public int getFieldSize()(Code) | | Returns the field size in bits which is m
for this characteristic 2 finite field.
the field size in bits. |
| getM | | public int getM()(Code) | | Returns the value m of this characteristic
2 finite field.
m with 2^m being the number of elements. |
| getMidTermsOfReductionPolynomial | | public int[] getMidTermsOfReductionPolynomial()(Code) | | 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.
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 | | public BigInteger getReductionPolynomial()(Code) | | 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.
a BigInteger whose i-th bit corresponds to the i-th coefficient of the reduction polynomial for polynomialbasis or null for normal basis. |
| hashCode | | public int hashCode()(Code) | | Returns a hash code value for this characteristic 2
finite field.
a hash code value. |
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