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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8. Note: this package includes the NTRU encryption algorithms.

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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 (http://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; } }





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