package org.spongycastle.crypto.params;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.text.DecimalFormat;
import org.spongycastle.crypto.Digest;
import org.spongycastle.crypto.digests.SHA256Digest;
import org.spongycastle.crypto.digests.SHA512Digest;
/**
* A set of parameters for NtruSign. Several predefined parameter sets are available and new ones can be created as well.
*/
public class NTRUSigningParameters
implements Cloneable
{
public int N;
public int q;
public int d, d1, d2, d3, B;
double beta;
public double betaSq;
double normBound;
public double normBoundSq;
public int signFailTolerance = 100;
int bitsF = 6; // max #bits needed to encode one coefficient of the polynomial F
public Digest hashAlg;
/**
* Constructs a parameter set that uses ternary private keys (i.e. </code>polyType=SIMPLE</code>).
*
* @param N number of polynomial coefficients
* @param q modulus
* @param d number of -1's in the private polynomials <code>f</code> and <code>g</code>
* @param B number of perturbations
* @param beta balancing factor for the transpose lattice
* @param normBound maximum norm for valid signatures
* @param hashAlg a valid identifier for a <code>java.security.MessageDigest</code> instance such as <code>SHA-256</code>. The <code>MessageDigest</code> must support the <code>getDigestLength()</code> method.
*/
public NTRUSigningParameters(int N, int q, int d, int B, double beta, double normBound, Digest hashAlg)
{
this.N = N;
this.q = q;
this.d = d;
this.B = B;
this.beta = beta;
this.normBound = normBound;
this.hashAlg = hashAlg;
init();
}
/**
* Constructs a parameter set that uses product-form private keys (i.e. </code>polyType=PRODUCT</code>).
*
* @param N number of polynomial coefficients
* @param q modulus
* @param d1 number of -1's in the private polynomials <code>f</code> and <code>g</code>
* @param d2 number of -1's in the private polynomials <code>f</code> and <code>g</code>
* @param d3 number of -1's in the private polynomials <code>f</code> and <code>g</code>
* @param B number of perturbations
* @param beta balancing factor for the transpose lattice
* @param normBound maximum norm for valid signatures
* @param keyNormBound maximum norm for the ploynomials <code>F</code> and <code>G</code>
* @param hashAlg a valid identifier for a <code>java.security.MessageDigest</code> instance such as <code>SHA-256</code>. The <code>MessageDigest</code> must support the <code>getDigestLength()</code> method.
*/
public NTRUSigningParameters(int N, int q, int d1, int d2, int d3, int B, double beta, double normBound, double keyNormBound, Digest hashAlg)
{
this.N = N;
this.q = q;
this.d1 = d1;
this.d2 = d2;
this.d3 = d3;
this.B = B;
this.beta = beta;
this.normBound = normBound;
this.hashAlg = hashAlg;
init();
}
private void init()
{
betaSq = beta * beta;
normBoundSq = normBound * normBound;
}
/**
* Reads a parameter set from an input stream.
*
* @param is an input stream
* @throws IOException
*/
public NTRUSigningParameters(InputStream is)
throws IOException
{
DataInputStream dis = new DataInputStream(is);
N = dis.readInt();
q = dis.readInt();
d = dis.readInt();
d1 = dis.readInt();
d2 = dis.readInt();
d3 = dis.readInt();
B = dis.readInt();
beta = dis.readDouble();
normBound = dis.readDouble();
signFailTolerance = dis.readInt();
bitsF = dis.readInt();
String alg = dis.readUTF();
if ("SHA-512".equals(alg))
{
hashAlg = new SHA512Digest();
}
else if ("SHA-256".equals(alg))
{
hashAlg = new SHA256Digest();
}
init();
}
/**
* Writes the parameter set to an output stream
*
* @param os an output stream
* @throws IOException
*/
public void writeTo(OutputStream os)
throws IOException
{
DataOutputStream dos = new DataOutputStream(os);
dos.writeInt(N);
dos.writeInt(q);
dos.writeInt(d);
dos.writeInt(d1);
dos.writeInt(d2);
dos.writeInt(d3);
dos.writeInt(B);
dos.writeDouble(beta);
dos.writeDouble(normBound);
dos.writeInt(signFailTolerance);
dos.writeInt(bitsF);
dos.writeUTF(hashAlg.getAlgorithmName());
}
public NTRUSigningParameters clone()
{
return new NTRUSigningParameters(N, q, d, B, beta, normBound, hashAlg);
}
public int hashCode()
{
final int prime = 31;
int result = 1;
result = prime * result + B;
result = prime * result + N;
long temp;
temp = Double.doubleToLongBits(beta);
result = prime * result + (int)(temp ^ (temp >>> 32));
temp = Double.doubleToLongBits(betaSq);
result = prime * result + (int)(temp ^ (temp >>> 32));
result = prime * result + bitsF;
result = prime * result + d;
result = prime * result + d1;
result = prime * result + d2;
result = prime * result + d3;
result = prime * result + ((hashAlg == null) ? 0 : hashAlg.getAlgorithmName().hashCode());
temp = Double.doubleToLongBits(normBound);
result = prime * result + (int)(temp ^ (temp >>> 32));
temp = Double.doubleToLongBits(normBoundSq);
result = prime * result + (int)(temp ^ (temp >>> 32));
result = prime * result + q;
result = prime * result + signFailTolerance;
return result;
}
public boolean equals(Object obj)
{
if (this == obj)
{
return true;
}
if (obj == null)
{
return false;
}
if (!(obj instanceof NTRUSigningParameters))
{
return false;
}
NTRUSigningParameters other = (NTRUSigningParameters)obj;
if (B != other.B)
{
return false;
}
if (N != other.N)
{
return false;
}
if (Double.doubleToLongBits(beta) != Double.doubleToLongBits(other.beta))
{
return false;
}
if (Double.doubleToLongBits(betaSq) != Double.doubleToLongBits(other.betaSq))
{
return false;
}
if (bitsF != other.bitsF)
{
return false;
}
if (d != other.d)
{
return false;
}
if (d1 != other.d1)
{
return false;
}
if (d2 != other.d2)
{
return false;
}
if (d3 != other.d3)
{
return false;
}
if (hashAlg == null)
{
if (other.hashAlg != null)
{
return false;
}
}
else if (!hashAlg.getAlgorithmName().equals(other.hashAlg.getAlgorithmName()))
{
return false;
}
if (Double.doubleToLongBits(normBound) != Double.doubleToLongBits(other.normBound))
{
return false;
}
if (Double.doubleToLongBits(normBoundSq) != Double.doubleToLongBits(other.normBoundSq))
{
return false;
}
if (q != other.q)
{
return false;
}
if (signFailTolerance != other.signFailTolerance)
{
return false;
}
return true;
}
public String toString()
{
DecimalFormat format = new DecimalFormat("0.00");
StringBuilder output = new StringBuilder("SignatureParameters(N=" + N + " q=" + q);
output.append(" B=" + B + " beta=" + format.format(beta) +
" normBound=" + format.format(normBound) +
" hashAlg=" + hashAlg + ")");
return output.toString();
}
}