/******************************************************************************
* NTRU Cryptography Reference Source Code
* Copyright (c) 2009-2013, by Security Innovation, Inc. All rights reserved.
*
* Copyright (C) 2009-2013 Security Innovation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*********************************************************************************/
package com.securityinnovation.jNeo.ntruencrypt.encoder;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import com.securityinnovation.jNeo.ParamSetNotSupportedException;
import com.securityinnovation.jNeo.math.FullPolynomial;
import com.securityinnovation.jNeo.math.MGF_TP_1;
import com.securityinnovation.jNeo.math.BitPack;
import com.securityinnovation.jNeo.ntruencrypt.KeyParams;
class PrivKeyFormatter_PrivateKeyListedFv1 implements PrivKeyFormatter
{
private final static byte tag = NtruEncryptKeyNativeEncoder.PRIVATE_KEY_DEFAULT_v1;
public byte[] encode(
KeyParams keyParams,
FullPolynomial h,
FullPolynomial f)
{
// Sanity-check inputs
if ((h.p.length != keyParams.N) || (f.p.length != keyParams.N))
return null;
// Convert f to a listed F.
FullPolynomial F = KeyFormatterUtil.recoverF(f);
// Allocate output buffer
int len = (KeyFormatterUtil.fillHeader(tag, keyParams.OIDBytes, null) +
BitPack.pack(keyParams.N, keyParams.q) +
BitPack.pack(2*keyParams.df, keyParams.N));
byte ret[] = new byte[len];
// Encode the output
int offset = KeyFormatterUtil.fillHeader(tag, keyParams.OIDBytes, ret);
offset += BitPack.pack(
keyParams.N, keyParams.q, h.p, 0, ret, offset);
offset += KeyFormatterUtil.packListedCoefficients(
F, keyParams.df, keyParams.df, ret, offset);
return ret;
}
public RawKeyData decode(
byte keyBlob[])
throws ParamSetNotSupportedException
{
// Parse the header, recover the key parameters.
if (keyBlob[0] != tag)
throw new IllegalArgumentException("key blob tag not recognized");
KeyParams keyParams = KeyFormatterUtil.parseOID(keyBlob, 1, 3);
// Make sure the input will be fully consumed
int headerLen = KeyFormatterUtil.getHeaderEndOffset(keyBlob);
int packedHLen = BitPack.unpack(keyParams.N, keyParams.q);
int listedFLen = BitPack.unpack(2*keyParams.df, keyParams.N);
if (headerLen + packedHLen + listedFLen != keyBlob.length)
throw new IllegalArgumentException("blob length invalid");
// Recover h
int offset = headerLen;
FullPolynomial h = new FullPolynomial(keyParams.N);
offset += BitPack.unpack(
keyParams.N, keyParams.q, keyBlob, offset, h.p, 0);
// Recover F
FullPolynomial f = new FullPolynomial(keyParams.N);
offset += KeyFormatterUtil.unpackListedCoefficients(
f, keyParams.N, keyParams.df, keyParams.df, keyBlob, offset);
// Compute f = 1+p*F
for (int i=0; i<f.p.length; i++)
f.p[i] *= keyParams.p;
f.p[0]++;
// Return the key material
return new RawKeyData(keyParams, h, f);
}
}