package org.bouncycastle.pqc.jcajce.spec;

import java.security.spec.AlgorithmParameterSpec;

import org.bouncycastle.util.Arrays;

This class provides methods for setting and getting the Rainbow-parameters
like number of Vinegar-variables in the layers, number of layers and so on.

More detailed information about the needed parameters for the Rainbow
Signature Scheme is to be found in the paper of Jintai Ding, Dieter Schmidt:
Rainbow, a New Multivariable Polynomial Signature Scheme. ACNS 2005: 164-175
(http://dx.doi.org/10.1007/11496137_12)

/**
 * This class provides methods for setting and getting the Rainbow-parameters
 * like number of Vinegar-variables in the layers, number of layers and so on.
 * <p>
 * More detailed information about the needed parameters for the Rainbow
 * Signature Scheme is to be found in the paper of Jintai Ding, Dieter Schmidt:
 * Rainbow, a New Multivariable Polynomial Signature Scheme. ACNS 2005: 164-175
 * (http://dx.doi.org/10.1007/11496137_12)
 * </p>
 */
public class RainbowParameterSpec
    implements AlgorithmParameterSpec
{

    
DEFAULT PARAMS
/**
     * DEFAULT PARAMS
     */
    /*
      * Vi = vinegars per layer whereas n is vu (vu = 33 = n) such that
      *
      * v1 = 6; o1 = 12-6 = 6
      *
      * v2 = 12; o2 = 17-12 = 5
      *
      * v3 = 17; o3 = 22-17 = 5
      *
      * v4 = 22; o4 = 33-22 = 11
      *
      * v5 = 33; (o5 = 0)
      */
    private static final int[] DEFAULT_VI = {6, 12, 17, 22, 33};

    private int[] vi;// set of vinegar vars per layer.

    
Default Constructor The elements of the array containing the number of
Vinegar variables in each layer are set to the default values here.
/**
     * Default Constructor The elements of the array containing the number of
     * Vinegar variables in each layer are set to the default values here.
     */
    public RainbowParameterSpec()
    {
        this.vi = DEFAULT_VI;
    }

    
Constructor with parameters
Params:
vi – The elements of the array containing the number of Vinegar
          variables per layer are set to the values of the input array.
Throws:
IllegalArgumentException – if the variables are invalid./**
     * Constructor with parameters
     *
     * @param vi The elements of the array containing the number of Vinegar
     *           variables per layer are set to the values of the input array.
     * @throws IllegalArgumentException if the variables are invalid.
     */
    public RainbowParameterSpec(int[] vi)
    {
        this.vi = vi;

        checkParams();
    }

    private void checkParams()
    {
        if (vi == null)
        {
            throw new IllegalArgumentException("no layers defined.");
        }
        if (vi.length > 1)
        {
            for (int i = 0; i < vi.length - 1; i++)
            {
                if (vi[i] >= vi[i + 1])
                {
                    throw new IllegalArgumentException(
                        "v[i] has to be smaller than v[i+1]");
                }
            }
        }
        else
        {
            throw new IllegalArgumentException(
                "Rainbow needs at least 1 layer, such that v1 < v2.");
        }
    }

    
Getter for the number of layers
Returns:
the number of layers/**
     * Getter for the number of layers
     *
     * @return the number of layers
     */
    public int getNumOfLayers()
    {
        return this.vi.length - 1;
    }

    
Getter for the number of all the polynomials in Rainbow
Returns:
the number of the polynomials/**
     * Getter for the number of all the polynomials in Rainbow
     *
     * @return the number of the polynomials
     */
    public int getDocumentLength()
    {
        return vi[vi.length - 1] - vi[0];
    }

    
Getter for the array containing the number of Vinegar-variables per layer
Returns:
the numbers of vinegars per layer/**
     * Getter for the array containing the number of Vinegar-variables per layer
     *
     * @return the numbers of vinegars per layer
     */
    public int[] getVi()
    {
        return Arrays.clone(this.vi);
    }
}