Package org.bouncycastle.pqc.legacy.math.ntru.util

Class ArrayEncoder

java.lang.Object
org.bouncycastle.pqc.legacy.math.ntru.util.ArrayEncoder
public class ArrayEncoder extends Object
Converts a coefficient array to a compact byte array and vice versa.

  • Constructor Details

    • ArrayEncoder

      public ArrayEncoder()

  • Method Details

    • 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(InputStream is, int N, int q) throws 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:
      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(InputStream is, int N) throws 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:
      IOException