org.spongycastle.pqc.math.linearalgebra

Class Permutation

java.lang.Object

org.spongycastle.pqc.math.linearalgebra.Permutation

public class Permutation
extends java.lang.Object

This class implements permutations of the set {0,1,...,n-1} for some given n > 0, i.e., ordered sequences containing each number m (0 <= m < n) once and only once.

Constructor Summary

Constructors

Constructor and Description
Permutation(byte[] enc) Create a permutation from an encoded permutation.
Permutation(int n) Create the identity permutation of the given size.
Permutation(int[] perm) Create a permutation using the given permutation vector.
Permutation(int n, java.security.SecureRandom sr) Create a random permutation of the given size.

Method Summary

Modifier and Type	Method and Description
Permutation	computeInverse() Compute the inverse permutation P-1.
boolean	equals(java.lang.Object other) checks if given object is equal to this permutation.
byte[]	getEncoded() Encode this permutation as byte array.
int[]	getVector()
int	hashCode()
Permutation	rightMultiply(Permutation p) Compute the product of this permutation and another permutation.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Permutation

public Permutation(int n)

Create the identity permutation of the given size.

Parameters:

n - the size of the permutation

Permutation

public Permutation(int[] perm)

Create a permutation using the given permutation vector.

Parameters:

perm - the permutation vector

Permutation

public Permutation(byte[] enc)

Create a permutation from an encoded permutation.

Parameters:

enc - the encoded permutation

Permutation

public Permutation(int n,
                   java.security.SecureRandom sr)

Create a random permutation of the given size.

Parameters:

n - the size of the permutation

sr - the source of randomness

Method Detail

getEncoded

public byte[] getEncoded()

Encode this permutation as byte array.

Returns:

the encoded permutation

getVector

public int[] getVector()

Returns:

the permutation vector (perm(0),perm(1),...,perm(n-1))

computeInverse

public Permutation computeInverse()

Compute the inverse permutation P^-1.

Returns:

this^-1

rightMultiply

public Permutation rightMultiply(Permutation p)

Compute the product of this permutation and another permutation.

Parameters:

p - the other permutation

Returns:

this * p

equals

public boolean equals(java.lang.Object other)

checks if given object is equal to this permutation.

The method returns false whenever the given object is not permutation.

Overrides:

equals in class java.lang.Object

Parameters:

other - - permutation

Returns:

true or false

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

a human readable form of the permutation

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code of this permutation