| package org.bouncycastle.pqc.jcajce.spec; |
| |
| import java.security.InvalidParameterException; |
| import java.security.spec.AlgorithmParameterSpec; |
| |
| import org.bouncycastle.pqc.math.linearalgebra.PolynomialRingGF2; |
| |
| /** |
| * This class provides a specification for the parameters that are used by the |
| * McEliece, McElieceCCA2, and Niederreiter key pair generators. |
| */ |
| public class McElieceKeyGenParameterSpec |
| implements AlgorithmParameterSpec |
| { |
| |
| /** |
| * The default extension degree |
| */ |
| public static final int DEFAULT_M = 11; |
| |
| /** |
| * The default error correcting capability. |
| */ |
| public static final int DEFAULT_T = 50; |
| |
| /** |
| * extension degree of the finite field GF(2^m) |
| */ |
| private int m; |
| |
| /** |
| * error correction capability of the code |
| */ |
| private int t; |
| |
| /** |
| * length of the code |
| */ |
| private int n; |
| |
| /** |
| * the field polynomial |
| */ |
| private int fieldPoly; |
| |
| /** |
| * Constructor. Set the default parameters: extension degree. |
| */ |
| public McElieceKeyGenParameterSpec() |
| { |
| this(DEFAULT_M, DEFAULT_T); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param keysize the length of a Goppa code |
| * @throws IllegalArgumentException if <tt>keysize < 1</tt>. |
| */ |
| public McElieceKeyGenParameterSpec(int keysize) |
| { |
| if (keysize < 1) |
| { |
| throw new IllegalArgumentException("key size must be positive"); |
| } |
| m = 0; |
| n = 1; |
| while (n < keysize) |
| { |
| n <<= 1; |
| m++; |
| } |
| t = n >>> 1; |
| t /= m; |
| fieldPoly = PolynomialRingGF2.getIrreduciblePolynomial(m); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param m degree of the finite field GF(2^m) |
| * @param t error correction capability of the code |
| * @throws InvalidParameterException if <tt>m < 1</tt> or <tt>m > 32</tt> or |
| * <tt>t < 0</tt> or <tt>t > n</tt>. |
| */ |
| public McElieceKeyGenParameterSpec(int m, int t) |
| throws InvalidParameterException |
| { |
| if (m < 1) |
| { |
| throw new IllegalArgumentException("m must be positive"); |
| } |
| if (m > 32) |
| { |
| throw new IllegalArgumentException("m is too large"); |
| } |
| this.m = m; |
| n = 1 << m; |
| if (t < 0) |
| { |
| throw new IllegalArgumentException("t must be positive"); |
| } |
| if (t > n) |
| { |
| throw new IllegalArgumentException("t must be less than n = 2^m"); |
| } |
| this.t = t; |
| fieldPoly = PolynomialRingGF2.getIrreduciblePolynomial(m); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param m degree of the finite field GF(2^m) |
| * @param t error correction capability of the code |
| * @param poly the field polynomial |
| * @throws IllegalArgumentException if <tt>m < 1</tt> or <tt>m > 32</tt> or |
| * <tt>t < 0</tt> or <tt>t > n</tt> or |
| * <tt>poly</tt> is not an irreducible field polynomial. |
| */ |
| public McElieceKeyGenParameterSpec(int m, int t, int poly) |
| { |
| this.m = m; |
| if (m < 1) |
| { |
| throw new IllegalArgumentException("m must be positive"); |
| } |
| if (m > 32) |
| { |
| throw new IllegalArgumentException(" m is too large"); |
| } |
| this.n = 1 << m; |
| this.t = t; |
| if (t < 0) |
| { |
| throw new IllegalArgumentException("t must be positive"); |
| } |
| if (t > n) |
| { |
| throw new IllegalArgumentException("t must be less than n = 2^m"); |
| } |
| if ((PolynomialRingGF2.degree(poly) == m) |
| && (PolynomialRingGF2.isIrreducible(poly))) |
| { |
| this.fieldPoly = poly; |
| } |
| else |
| { |
| throw new IllegalArgumentException( |
| "polynomial is not a field polynomial for GF(2^m)"); |
| } |
| } |
| |
| /** |
| * @return the extension degree of the finite field GF(2^m) |
| */ |
| public int getM() |
| { |
| return m; |
| } |
| |
| /** |
| * @return the length of the code |
| */ |
| public int getN() |
| { |
| return n; |
| } |
| |
| /** |
| * @return the error correction capability of the code |
| */ |
| public int getT() |
| { |
| return t; |
| } |
| |
| /** |
| * @return the field polynomial |
| */ |
| public int getFieldPoly() |
| { |
| return fieldPoly; |
| } |
| |
| } |