org.bouncycastle.pqc.math.ntru.util

Class ArrayEncoder

java.lang.Object

org.bouncycastle.pqc.math.ntru.util.ArrayEncoder

public class ArrayEncoder
extends java.lang.Object

Converts a coefficient array to a compact byte array and vice versa.

Constructor Summary

Constructors

Constructor and Description
ArrayEncoder()

Method Summary

Modifier and Type	Method and Description
static int[]	decodeMod3Sves(byte[] data, int N) Decodes a byte array encoded with encodeMod3Sves(int[]) back to an int array with N coefficients between -1 and 1.
static int[]	decodeMod3Tight(byte[] b, int N) Converts a byte array produced by encodeMod3Tight(int[]) back to an int array.
static int[]	decodeMod3Tight(java.io.InputStream is, int N) Converts data produced by encodeMod3Tight(int[]) back to an int array.
static int[]	decodeModQ(byte[] data, int N, int q) Decodes a byte array encoded with encodeModQ(int[], int) back to an int array.
static int[]	decodeModQ(java.io.InputStream is, int N, int q) Decodes data encoded with encodeModQ(int[], int) back to an int array.
static byte[]	encodeMod3Sves(int[] arr) Encodes an int array whose elements are between -1 and 1, to a byte array.
static byte[]	encodeMod3Tight(int[] intArray) Encodes an int array whose elements are between -1 and 1, to a byte array.
static byte[]	encodeModQ(int[] a, int q) Encodes an int array whose elements are between 0 and q, to a byte array leaving no gaps between bits.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayEncoder

public ArrayEncoder()

Method Detail

encodeModQ

public static byte[] encodeModQ(int[] a,
                                int q)

Encodes an int array whose elements are between 0 and q, to a byte array leaving no gaps between bits.
q must be a power of 2.

Parameters:

a - the input array

q - the modulus

Returns:

the encoded array

decodeModQ

public static int[] decodeModQ(byte[] data,
                               int N,
                               int q)

Decodes a byte array encoded with encodeModQ(int[], int) back to an int array.
N is the number of coefficients. q must be a power of 2.
Ignores any excess bytes.

Parameters:

data - an encoded ternary polynomial

N - number of coefficients

q -

Returns:

an array containing N coefficients between 0 and q-1

decodeModQ

public static int[] decodeModQ(java.io.InputStream is,
                               int N,
                               int q)
                        throws java.io.IOException

Decodes data encoded with encodeModQ(int[], int) back to an int array.
N is the number of coefficients. q must be a power of 2.
Ignores any excess bytes.

Parameters:

is - an encoded ternary polynomial

N - number of coefficients

q -

Returns:

the decoded polynomial

Throws:

java.io.IOException

decodeMod3Sves

public static int[] decodeMod3Sves(byte[] data,
                                   int N)

Decodes a byte array encoded with encodeMod3Sves(int[]) back to an int array with N coefficients between -1 and 1.
Ignores any excess bytes.
See P1363.1 section 9.2.2.

Parameters:

data - an encoded ternary polynomial

N - number of coefficients

Returns:

the decoded coefficients

encodeMod3Sves

public static byte[] encodeMod3Sves(int[] arr)

Encodes an int array whose elements are between -1 and 1, to a byte array. coeffs[2*i] and coeffs[2*i+1] must not both equal -1 for any integer i, so this method is only safe to use with arrays produced by decodeMod3Sves(byte[], int).
See P1363.1 section 9.2.3.

Parameters:

arr -

Returns:

the encoded array

encodeMod3Tight

public static byte[] encodeMod3Tight(int[] intArray)

Encodes an int array whose elements are between -1 and 1, to a byte array.

Returns:

the encoded array

decodeMod3Tight

public static int[] decodeMod3Tight(byte[] b,
                                    int N)

Converts a byte array produced by encodeMod3Tight(int[]) back to an int array.

Parameters:

b - a byte array

N - number of coefficients

Returns:

the decoded array

decodeMod3Tight

public static int[] decodeMod3Tight(java.io.InputStream is,
                                    int N)
                             throws java.io.IOException

Converts data produced by encodeMod3Tight(int[]) back to an int array.

Parameters:

is - an input stream containing the data to decode

N - number of coefficients

Returns:

the decoded array

Throws:

java.io.IOException