Package org.bouncycastle.util

Class GF16

java.lang.Object
org.bouncycastle.util.GF16
public class GF16 extends Object

  • Constructor Summary

    Constructors
    Constructor
    Description
    GF16()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static void
    decode(byte[] input, byte[] output, int outputLen)
    Decodes an encoded byte array.
    static void
    decode(byte[] input, int inOff, byte[] output, int outOff, int outputLen)
     
    static void
    encode(byte[] input, byte[] output, int inputLen)
    Encodes an array of 4-bit values into a byte array.
    static void
    encode(byte[] input, byte[] output, int outOff, int inputLen)
     
    static byte
    innerProduct(byte[] a, int aOff, byte[] b, int bOff, int rank)
     
    static byte
    inv(byte a)
    Computes the multiplicative inverse in GF(16) for a GF(16) element.
    static byte
    mul(byte a, byte b)
    GF(16) multiplication mod x^4 + x + 1.
    static int
    mul(int a, int b)
    GF(16) multiplication mod x^4 + x + 1.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • GF16

      public GF16()

  • Method Details

    • mul

      public static byte mul(byte a, byte b)
      GF(16) multiplication mod x^4 + x + 1.

      This method multiplies two elements in GF(16) (represented as integers 0–15) using carryless multiplication followed by reduction modulo x^4 + x + 1. Please ensure a <= 0x0F and b <= 0x0F

      Parameters:
      a - an element in GF(16) (only the lower 4 bits are used)
      b - an element in GF(16) (only the lower 4 bits are used)
      Returns:
      the product a * b in GF(16)

    • mul

      public static int mul(int a, int b)
      GF(16) multiplication mod x^4 + x + 1.

      This method multiplies two elements in GF(16) (represented as integers 0–15) using carryless multiplication followed by reduction modulo x^4 + x + 1. Please ensure a <= 0x0F and b <= 0x0F

      Parameters:
      a - an element in GF(16) (only the lower 4 bits are used)
      b - an element in GF(16) (only the lower 4 bits are used)
      Returns:
      the product a * b in GF(16)

    • inv

      public static byte inv(byte a)
      Computes the multiplicative inverse in GF(16) for a GF(16) element.

    • decode

      public static void decode(byte[] input, byte[] output, int outputLen)
      Decodes an encoded byte array. Each byte in the input contains two nibbles (4-bit values); the lower nibble is stored first, followed by the upper nibble.
      Parameters:
      input - the input byte array (each byte holds two 4-bit values)
      output - the output array that will hold the decoded nibbles (one per byte)
      outputLen - the total number of nibbles to decode

    • decode

      public static void decode(byte[] input, int inOff, byte[] output, int outOff, int outputLen)

    • encode

      public static void encode(byte[] input, byte[] output, int inputLen)
      Encodes an array of 4-bit values into a byte array. Two 4-bit values are packed into one byte, with the first nibble stored in the lower 4 bits and the second nibble stored in the upper 4 bits.
      Parameters:
      input - the input array of 4-bit values (stored as bytes, only lower 4 bits used)
      output - the output byte array that will hold the encoded bytes
      inputLen - the number of nibbles in the input array

    • encode

      public static void encode(byte[] input, byte[] output, int outOff, int inputLen)

    • innerProduct

      public static byte innerProduct(byte[] a, int aOff, byte[] b, int bOff, int rank)