org.bouncycastle.pqc.crypto.rainbow.Layer Maven / Gradle / Ivy
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package org.bouncycastle.pqc.crypto.rainbow;
import java.security.SecureRandom;
import org.bouncycastle.pqc.crypto.rainbow.util.GF2Field;
import org.bouncycastle.pqc.crypto.rainbow.util.RainbowUtil;
import org.bouncycastle.util.Arrays;
/**
* This class represents a layer of the Rainbow Oil- and Vinegar Map. Each Layer
* consists of oi polynomials with their coefficients, generated at random.
*
* To sign a document, we solve a LES (linear equation system) for each layer in
* order to find the oil variables of that layer and to be able to use the
* variables to compute the signature. This functionality is implemented in the
* RainbowSignature-class, by the aid of the private key.
*
* Each layer is a part of the private key.
*
* More information about the layer can be found in the paper of Jintai Ding,
* Dieter Schmidt: Rainbow, a New Multivariable Polynomial Signature Scheme.
* ACNS 2005: 164-175 (https://dx.doi.org/10.1007/11496137_12)
*/
public class Layer
{
private int vi; // number of vinegars in this layer
private int viNext; // number of vinegars in next layer
private int oi; // number of oils in this layer
/*
* k : index of polynomial
*
* i,j : indices of oil and vinegar variables
*/
private short[/* k */][/* i */][/* j */] coeff_alpha;
private short[/* k */][/* i */][/* j */] coeff_beta;
private short[/* k */][/* i */] coeff_gamma;
private short[/* k */] coeff_eta;
/**
* Constructor
*
* @param vi number of vinegar variables of this layer
* @param viNext number of vinegar variables of next layer. It's the same as
* (num of oils) + (num of vinegars) of this layer.
* @param coeffAlpha alpha-coefficients in the polynomials of this layer
* @param coeffBeta beta-coefficients in the polynomials of this layer
* @param coeffGamma gamma-coefficients in the polynomials of this layer
* @param coeffEta eta-coefficients in the polynomials of this layer
*/
public Layer(byte vi, byte viNext, short[][][] coeffAlpha,
short[][][] coeffBeta, short[][] coeffGamma, short[] coeffEta)
{
this.vi = vi & 0xff;
this.viNext = viNext & 0xff;
this.oi = this.viNext - this.vi;
// the secret coefficients of all polynomials in this layer
this.coeff_alpha = coeffAlpha;
this.coeff_beta = coeffBeta;
this.coeff_gamma = coeffGamma;
this.coeff_eta = coeffEta;
}
/**
* This function generates the coefficients of all polynomials in this layer
* at random using random generator.
*
* @param sr the random generator which is to be used
*/
public Layer(int vi, int viNext, SecureRandom sr)
{
this.vi = vi;
this.viNext = viNext;
this.oi = viNext - vi;
// the coefficients of all polynomials in this layer
this.coeff_alpha = new short[this.oi][this.oi][this.vi];
this.coeff_beta = new short[this.oi][this.vi][this.vi];
this.coeff_gamma = new short[this.oi][this.viNext];
this.coeff_eta = new short[this.oi];
int numOfPoly = this.oi; // number of polynomials per layer
// Alpha coeffs
for (int k = 0; k < numOfPoly; k++)
{
for (int i = 0; i < this.oi; i++)
{
for (int j = 0; j < this.vi; j++)
{
coeff_alpha[k][i][j] = (short)(sr.nextInt() & GF2Field.MASK);
}
}
}
// Beta coeffs
for (int k = 0; k < numOfPoly; k++)
{
for (int i = 0; i < this.vi; i++)
{
for (int j = 0; j < this.vi; j++)
{
coeff_beta[k][i][j] = (short)(sr.nextInt() & GF2Field.MASK);
}
}
}
// Gamma coeffs
for (int k = 0; k < numOfPoly; k++)
{
for (int i = 0; i < this.viNext; i++)
{
coeff_gamma[k][i] = (short)(sr.nextInt() & GF2Field.MASK);
}
}
// Eta
for (int k = 0; k < numOfPoly; k++)
{
coeff_eta[k] = (short)(sr.nextInt() & GF2Field.MASK);
}
}
/**
* This method plugs in the vinegar variables into the polynomials of this
* layer and computes the coefficients of the Oil-variables as well as the
* free coefficient in each polynomial.
*
* It is needed for computing the Oil variables while signing.
*
* @param x vinegar variables of this layer that should be plugged into
* the polynomials.
* @return coeff the coefficients of Oil variables and the free coeff in the
* polynomials of this layer.
*/
public short[][] plugInVinegars(short[] x)
{
// temporary variable needed for the multiplication
short tmpMult = 0;
// coeff: 1st index = which polynomial, 2nd index=which variable
short[][] coeff = new short[oi][oi + 1]; // gets returned
// free coefficient per polynomial
short[] sum = new short[oi];
/*
* evaluate the beta-part of the polynomials (it contains no oil
* variables)
*/
for (int k = 0; k < oi; k++)
{
for (int i = 0; i < vi; i++)
{
for (int j = 0; j < vi; j++)
{
// tmp = beta * xi (plug in)
tmpMult = GF2Field.multElem(coeff_beta[k][i][j], x[i]);
// tmp = tmp * xj
tmpMult = GF2Field.multElem(tmpMult, x[j]);
// accumulate into the array for the free coefficients.
sum[k] = GF2Field.addElem(sum[k], tmpMult);
}
}
}
/* evaluate the alpha-part (it contains oils) */
for (int k = 0; k < oi; k++)
{
for (int i = 0; i < oi; i++)
{
for (int j = 0; j < vi; j++)
{
// alpha * xj (plug in)
tmpMult = GF2Field.multElem(coeff_alpha[k][i][j], x[j]);
// accumulate
coeff[k][i] = GF2Field.addElem(coeff[k][i], tmpMult);
}
}
}
/* evaluate the gama-part of the polynomial (containing no oils) */
for (int k = 0; k < oi; k++)
{
for (int i = 0; i < vi; i++)
{
// gamma * xi (plug in)
tmpMult = GF2Field.multElem(coeff_gamma[k][i], x[i]);
// accumulate in the array for the free coefficients (per
// polynomial).
sum[k] = GF2Field.addElem(sum[k], tmpMult);
}
}
/* evaluate the gama-part of the polynomial (but containing oils) */
for (int k = 0; k < oi; k++)
{
for (int i = vi; i < viNext; i++)
{ // oils
// accumulate the coefficients of the oil variables (per
// polynomial).
coeff[k][i - vi] = GF2Field.addElem(coeff_gamma[k][i],
coeff[k][i - vi]);
}
}
/* evaluate the eta-part of the polynomial */
for (int k = 0; k < oi; k++)
{
// accumulate in the array for the free coefficients per polynomial.
sum[k] = GF2Field.addElem(sum[k], coeff_eta[k]);
}
/* put the free coefficients (sum) into the coeff-array as last column */
for (int k = 0; k < oi; k++)
{
coeff[k][oi] = sum[k];
}
return coeff;
}
/**
* Getter for the number of vinegar variables of this layer.
*
* @return the number of vinegar variables of this layer.
*/
public int getVi()
{
return vi;
}
/**
* Getter for the number of vinegar variables of the next layer.
*
* @return the number of vinegar variables of the next layer.
*/
public int getViNext()
{
return viNext;
}
/**
* Getter for the number of Oil variables of this layer.
*
* @return the number of oil variables of this layer.
*/
public int getOi()
{
return oi;
}
/**
* Getter for the alpha-coefficients of the polynomials in this layer.
*
* @return the coefficients of alpha-terms of this layer.
*/
public short[][][] getCoeffAlpha()
{
return coeff_alpha;
}
/**
* Getter for the beta-coefficients of the polynomials in this layer.
*
* @return the coefficients of beta-terms of this layer.
*/
public short[][][] getCoeffBeta()
{
return coeff_beta;
}
/**
* Getter for the gamma-coefficients of the polynomials in this layer.
*
* @return the coefficients of gamma-terms of this layer
*/
public short[][] getCoeffGamma()
{
return coeff_gamma;
}
/**
* Getter for the eta-coefficients of the polynomials in this layer.
*
* @return the coefficients eta of this layer
*/
public short[] getCoeffEta()
{
return coeff_eta;
}
/**
* This function compares this Layer with another object.
*
* @param other the other object
* @return the result of the comparison
*/
public boolean equals(Object other)
{
if (other == null || !(other instanceof Layer))
{
return false;
}
Layer otherLayer = (Layer)other;
return vi == otherLayer.getVi()
&& viNext == otherLayer.getViNext()
&& oi == otherLayer.getOi()
&& RainbowUtil.equals(coeff_alpha, otherLayer.getCoeffAlpha())
&& RainbowUtil.equals(coeff_beta, otherLayer.getCoeffBeta())
&& RainbowUtil.equals(coeff_gamma, otherLayer.getCoeffGamma())
&& RainbowUtil.equals(coeff_eta, otherLayer.getCoeffEta());
}
public int hashCode()
{
int hash = vi;
hash = hash * 37 + viNext;
hash = hash * 37 + oi;
hash = hash * 37 + Arrays.hashCode(coeff_alpha);
hash = hash * 37 + Arrays.hashCode(coeff_beta);
hash = hash * 37 + Arrays.hashCode(coeff_gamma);
hash = hash * 37 + Arrays.hashCode(coeff_eta);
return hash;
}
}