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package org.spongycastle.pqc.crypto.ntru;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.spongycastle.pqc.math.ntru.polynomial.DenseTernaryPolynomial;
import org.spongycastle.pqc.math.ntru.polynomial.IntegerPolynomial;
import org.spongycastle.pqc.math.ntru.polynomial.Polynomial;
import org.spongycastle.pqc.math.ntru.polynomial.ProductFormPolynomial;
import org.spongycastle.pqc.math.ntru.polynomial.SparseTernaryPolynomial;
/**
* A NtruEncrypt private key is essentially a polynomial named <code>f</code>
* which takes different forms depending on whether product-form polynomials are used,
* and on <code>fastP</code><br>
* The inverse of <code>f</code> modulo <code>p</code> is precomputed on initialization.
*/
public class NTRUEncryptionPrivateKeyParameters
extends NTRUEncryptionKeyParameters
{
public Polynomial t;
public IntegerPolynomial fp;
public IntegerPolynomial h;
/**
* Constructs a new private key from a polynomial
*
* @param h the public polynomial for the key.
* @param t the polynomial which determines the key: if <code>fastFp=true</code>, <code>f=1+3t</code>; otherwise, <code>f=t</code>
* @param fp the inverse of <code>f</code>
* @param params the NtruEncrypt parameters to use
*/
public NTRUEncryptionPrivateKeyParameters(IntegerPolynomial h, Polynomial t, IntegerPolynomial fp, NTRUEncryptionParameters params)
{
super(true, params);
this.h = h;
this.t = t;
this.fp = fp;
}
/**
* Converts a byte array to a polynomial <code>f</code> and constructs a new private key
*
* @param b an encoded polynomial
* @param params the NtruEncrypt parameters to use
* @see #getEncoded()
*/
public NTRUEncryptionPrivateKeyParameters(byte[] b, NTRUEncryptionParameters params)
throws IOException
{
this(new ByteArrayInputStream(b), params);
}
/**
* Reads a polynomial <code>f</code> from an input stream and constructs a new private key
*
* @param is an input stream
* @param params the NtruEncrypt parameters to use
* @see #writeTo(OutputStream)
*/
public NTRUEncryptionPrivateKeyParameters(InputStream is, NTRUEncryptionParameters params)
throws IOException
{
super(true, params);
if (params.polyType == NTRUParameters.TERNARY_POLYNOMIAL_TYPE_PRODUCT)
{
int N = params.N;
int df1 = params.df1;
int df2 = params.df2;
int df3Ones = params.df3;
int df3NegOnes = params.fastFp ? params.df3 : params.df3 - 1;
h = IntegerPolynomial.fromBinary(is, params.N, params.q);
t = ProductFormPolynomial.fromBinary(is, N, df1, df2, df3Ones, df3NegOnes);
}
else
{
h = IntegerPolynomial.fromBinary(is, params.N, params.q);
IntegerPolynomial fInt = IntegerPolynomial.fromBinary3Tight(is, params.N);
t = params.sparse ? new SparseTernaryPolynomial(fInt) : new DenseTernaryPolynomial(fInt);
}
init();
}
/**
* Initializes <code>fp</code> from t.
*/
private void init()
{
if (params.fastFp)
{
fp = new IntegerPolynomial(params.N);
fp.coeffs[0] = 1;
}
else
{
fp = t.toIntegerPolynomial().invertF3();
}
}
/**
* Converts the key to a byte array
*
* @return the encoded key
* @see #NTRUEncryptionPrivateKeyParameters(byte[], NTRUEncryptionParameters)
*/
public byte[] getEncoded()
{
byte[] hBytes = h.toBinary(params.q);
byte[] tBytes;
if (t instanceof ProductFormPolynomial)
{
tBytes = ((ProductFormPolynomial)t).toBinary();
}
else
{
tBytes = t.toIntegerPolynomial().toBinary3Tight();
}
byte[] res = new byte[hBytes.length + tBytes.length];
System.arraycopy(hBytes, 0, res, 0, hBytes.length);
System.arraycopy(tBytes, 0, res, hBytes.length, tBytes.length);
return res;
}
/**
* Writes the key to an output stream
*
* @param os an output stream
* @throws IOException
* @see #NTRUEncryptionPrivateKeyParameters(InputStream, NTRUEncryptionParameters)
*/
public void writeTo(OutputStream os)
throws IOException
{
os.write(getEncoded());
}
public int hashCode()
{
final int prime = 31;
int result = 1;
result = prime * result + ((params == null) ? 0 : params.hashCode());
result = prime * result + ((t == null) ? 0 : t.hashCode());
result = prime * result + ((h == null) ? 0 : h.hashCode());
return result;
}
public boolean equals(Object obj)
{
if (this == obj)
{
return true;
}
if (obj == null)
{
return false;
}
if (!(obj instanceof NTRUEncryptionPrivateKeyParameters))
{
return false;
}
NTRUEncryptionPrivateKeyParameters other = (NTRUEncryptionPrivateKeyParameters)obj;
if (params == null)
{
if (other.params != null)
{
return false;
}
}
else if (!params.equals(other.params))
{
return false;
}
if (t == null)
{
if (other.t != null)
{
return false;
}
}
else if (!t.equals(other.t))
{
return false;
}
if (!h.equals(other.h))
{
return false;
}
return true;
}
}
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