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jlechner |
/* RSA.java -- RSA PKCS#1 signatures.
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.security.provider;
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import gnu.java.security.OID;
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import gnu.java.security.der.DER;
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import gnu.java.security.der.DERReader;
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import gnu.java.security.der.DERValue;
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import gnu.java.security.der.DERWriter;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.math.BigInteger;
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import java.security.InvalidKeyException;
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import java.security.MessageDigest;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.SecureRandom;
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import java.security.SignatureException;
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import java.security.SignatureSpi;
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import java.security.interfaces.RSAPrivateKey;
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import java.security.interfaces.RSAPublicKey;
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import java.util.ArrayList;
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public abstract class RSA extends SignatureSpi implements Cloneable
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{
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// Constants and fields.
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// -------------------------------------------------------------------------
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/**
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* digestAlgorithm OBJECT IDENTIFIER ::=
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* { iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) }
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*/
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protected static final OID DIGEST_ALGORITHM = new OID("1.2.840.113549.2");
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protected final OID digestAlgorithm;
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protected final MessageDigest md;
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protected RSAPrivateKey signerKey;
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protected RSAPublicKey verifierKey;
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// Constructor.
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// -------------------------------------------------------------------------
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protected RSA(MessageDigest md, OID digestAlgorithm)
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{
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super();
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this.md = md;
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this.digestAlgorithm = digestAlgorithm;
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}
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// Instance methods.
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// -------------------------------------------------------------------------
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public Object clone() throws CloneNotSupportedException
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{
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return super.clone();
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}
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protected Object engineGetParameter(String param)
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{
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throw new UnsupportedOperationException("deprecated");
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}
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protected void engineSetParameter(String param, Object value)
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{
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throw new UnsupportedOperationException("deprecated");
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}
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protected void engineInitSign(PrivateKey privateKey)
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throws InvalidKeyException
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{
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if (!(privateKey instanceof RSAPrivateKey))
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throw new InvalidKeyException();
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verifierKey = null;
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signerKey = (RSAPrivateKey) privateKey;
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}
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protected void engineInitSign(PrivateKey privateKey, SecureRandom random)
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throws InvalidKeyException
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{
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// This class does not need random bytes.
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engineInitSign(privateKey);
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}
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protected void engineInitVerify(PublicKey publicKey)
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throws InvalidKeyException
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{
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if (!(publicKey instanceof RSAPublicKey))
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throw new InvalidKeyException();
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signerKey = null;
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verifierKey = (RSAPublicKey) publicKey;
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}
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protected void engineUpdate(byte b) throws SignatureException
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{
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if (signerKey == null && verifierKey == null)
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throw new SignatureException("not initialized");
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md.update(b);
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}
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protected void engineUpdate(byte[] buf, int off, int len)
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throws SignatureException
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{
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if (signerKey == null && verifierKey == null)
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throw new SignatureException("not initialized");
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md.update(buf, off, len);
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}
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protected byte[] engineSign() throws SignatureException
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{
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if (signerKey == null)
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throw new SignatureException("not initialized for signing");
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//
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// The signature will be the RSA encrypted BER representation of
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// the following:
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//
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// DigestInfo ::= SEQUENCE {
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// digestAlgorithm DigestAlgorithmIdentifier,
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// digest Digest }
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//
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// DigestAlgorithmIdentifier ::= AlgorithmIdentifier
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//
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// Digest ::= OCTET STRING
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//
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ArrayList digestAlg = new ArrayList(2);
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digestAlg.add(new DERValue(DER.OBJECT_IDENTIFIER, digestAlgorithm));
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digestAlg.add(new DERValue(DER.NULL, null));
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ArrayList digestInfo = new ArrayList(2);
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digestInfo.add(new DERValue(DER.SEQUENCE, digestAlg));
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digestInfo.add(new DERValue(DER.OCTET_STRING, md.digest()));
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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try
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{
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DERWriter.write(out, new DERValue(DER.SEQUENCE, digestInfo));
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}
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catch (IOException ioe)
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{
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throw new SignatureException(ioe.toString());
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}
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byte[] buf = out.toByteArray();
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md.reset();
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// k = octect length of the modulus.
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int k = signerKey.getModulus().bitLength();
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k = (k >>> 3) + ((k & 7) == 0 ? 0 : 1);
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if (buf.length < k - 3)
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{
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throw new SignatureException("RSA modulus too small");
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}
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byte[] d = new byte[k];
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// Padding type 1:
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// 00 | 01 | FF | ... | FF | 00 | D
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d[1] = 0x01;
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for (int i = 2; i < k - buf.length - 1; i++)
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d[i] = (byte) 0xFF;
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System.arraycopy(buf, 0, d, k - buf.length, buf.length);
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BigInteger eb = new BigInteger(d);
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byte[] ed = eb.modPow(signerKey.getPrivateExponent(),
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signerKey.getModulus()).toByteArray();
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// Ensure output is k octets long.
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if (ed.length < k)
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{
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byte[] b = new byte[k];
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System.arraycopy(eb, 0, b, k - ed.length, ed.length);
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ed = b;
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}
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else if (ed.length > k)
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{
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if (ed.length != k + 1)
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{
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throw new SignatureException("modPow result is larger than the modulus");
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}
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// Maybe an extra 00 octect.
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byte[] b = new byte[k];
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System.arraycopy(ed, 1, b, 0, k);
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ed = b;
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}
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return ed;
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}
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protected int engineSign(byte[] out, int off, int len)
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throws SignatureException
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{
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if (out == null || off < 0 || len < 0 || off+len > out.length)
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throw new SignatureException("illegal output argument");
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byte[] result = engineSign();
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if (result.length > len)
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throw new SignatureException("not enough space for signature");
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System.arraycopy(result, 0, out, off, result.length);
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return result.length;
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}
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protected boolean engineVerify(byte[] sig) throws SignatureException
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{
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if (verifierKey == null)
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throw new SignatureException("not initialized for verifying");
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if (sig == null)
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throw new SignatureException("no signature specified");
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int k = verifierKey.getModulus().bitLength();
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k = (k >>> 3) + ((k & 7) == 0 ? 0 : 1);
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if (sig.length != k)
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throw new SignatureException("signature is the wrong size (expecting "
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+ k + " bytes, got " + sig.length + ")");
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BigInteger ed = new BigInteger(1, sig);
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byte[] eb = ed.modPow(verifierKey.getPublicExponent(),
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verifierKey.getModulus()).toByteArray();
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int i = 0;
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if (eb[0] == 0x00)
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{
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for (i = 1; i < eb.length && eb[i] == 0x00; i++);
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if (i == 1)
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throw new SignatureException("wrong RSA padding");
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i--;
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}
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else if (eb[0] == 0x01)
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{
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for (i = 1; i < eb.length && eb[i] != 0x00; i++)
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if (eb[i] != (byte) 0xFF)
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throw new IllegalArgumentException("wrong RSA padding");
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}
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else
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throw new SignatureException("wrong RSA padding type");
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byte[] d = new byte[eb.length-i-1];
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System.arraycopy(eb, i+1, d, 0, eb.length-i-1);
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DERReader der = new DERReader(d);
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try
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{
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DERValue val = der.read();
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if (val.getTag() != DER.SEQUENCE)
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throw new SignatureException("failed to parse DigestInfo");
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val = der.read();
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if (val.getTag() != DER.SEQUENCE)
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throw new SignatureException("failed to parse DigestAlgorithmIdentifier");
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boolean sequenceIsBer = val.getLength() == 0;
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val = der.read();
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if (val.getTag() != DER.OBJECT_IDENTIFIER)
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throw new SignatureException("failed to parse object identifier");
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if (!val.getValue().equals(digestAlgorithm))
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throw new SignatureException("digest algorithms do not match");
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val = der.read();
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// We should never see parameters here, since they are never used.
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if (val.getTag() != DER.NULL)
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throw new SignatureException("cannot handle digest parameters");
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if (sequenceIsBer)
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der.skip(1); // end-of-sequence byte.
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val = der.read();
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if (val.getTag() != DER.OCTET_STRING)
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throw new SignatureException("failed to parse Digest");
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return MessageDigest.isEqual(md.digest(), (byte[]) val.getValue());
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}
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catch (IOException ioe)
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{
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throw new SignatureException(ioe.toString());
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}
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}
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protected boolean engineVerify(byte[] sig, int off, int len)
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throws SignatureException
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{
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if (sig == null || off < 0 || len < 0 || off+len > sig.length)
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throw new SignatureException("illegal parameter");
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byte[] buf = new byte[len];
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System.arraycopy(sig, off, buf, 0, len);
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return engineVerify(buf);
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}
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}
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