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/*
* Copyright 2015 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.UnrecoverableKeyException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.Enumeration;
import org.apache.pdfbox.pdmodel.interactive.digitalsignature.SignatureInterface;
import org.bouncycastle.cert.jcajce.JcaCertStore;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.OperatorCreationException;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;
public abstract class CreateSignatureBase implements SignatureInterface
{
private PrivateKey privateKey;
private Certificate[] certificateChain;
private String tsaUrl;
private boolean externalSigning;
/**
* Initialize the signature creator with a keystore (pkcs12) and pin that should be used for the
* signature.
*
* @param keystore is a pkcs12 keystore.
* @param pin is the pin for the keystore / private key
* @throws KeyStoreException if the keystore has not been initialized (loaded)
* @throws NoSuchAlgorithmException if the algorithm for recovering the key cannot be found
* @throws UnrecoverableKeyException if the given password is wrong
* @throws CertificateException if the certificate is not valid as signing time
* @throws IOException if no certificate could be found
*/
public CreateSignatureBase(KeyStore keystore, char[] pin)
throws KeyStoreException, UnrecoverableKeyException, NoSuchAlgorithmException, IOException, CertificateException
{
// grabs the first alias from the keystore and get the private key. An
// alternative method or constructor could be used for setting a specific
// alias that should be used.
Enumeration<String> aliases = keystore.aliases();
String alias;
Certificate cert = null;
while (aliases.hasMoreElements())
{
alias = aliases.nextElement();
setPrivateKey((PrivateKey) keystore.getKey(alias, pin));
Certificate[] certChain = keystore.getCertificateChain(alias);
if (certChain == null)
{
continue;
}
setCertificateChain(certChain);
cert = certChain[0];
if (cert instanceof X509Certificate)
{
// avoid expired certificate
((X509Certificate) cert).checkValidity();
SigUtils.checkCertificateUsage((X509Certificate) cert);
}
break;
}
if (cert == null)
{
throw new IOException("Could not find certificate");
}
}
public final void setPrivateKey(PrivateKey privateKey)
{
this.privateKey = privateKey;
}
public final void setCertificateChain(final Certificate[] certificateChain)
{
this.certificateChain = certificateChain;
}
public Certificate[] getCertificateChain()
{
return certificateChain;
}
public void setTsaUrl(String tsaUrl)
{
this.tsaUrl = tsaUrl;
}
/**
* SignatureInterface implementation.
*
* This method will be called from inside of the pdfbox and create the PKCS #7 signature.
* The given InputStream contains the bytes that are given by the byte range.
*
* This method is for internal use only.
*
* Use your favorite cryptographic library to implement PKCS #7 signature creation.
*
* @throws IOException
*/
@Override
public byte[] sign(InputStream content) throws IOException
{
// cannot be done private (interface)
try
{
CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
X509Certificate cert = (X509Certificate) certificateChain[0];
ContentSigner sha1Signer = new JcaContentSignerBuilder("SHA256WithRSA").build(privateKey);
gen.addSignerInfoGenerator(new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().build()).build(sha1Signer, cert));
gen.addCertificates(new JcaCertStore(Arrays.asList(certificateChain)));
CMSProcessableInputStream msg = new CMSProcessableInputStream(content);
CMSSignedData signedData = gen.generate(msg, false);
return signedData.getEncoded();
}
catch (GeneralSecurityException e)
{
throw new IOException(e);
}
catch (CMSException e)
{
throw new IOException(e);
}
catch (OperatorCreationException e)
{
throw new IOException(e);
}
}
/**
* Set if external signing scenario should be used.
* If {@code false}, SignatureInterface would be used for signing.
* <p>
* Default: {@code false}
* </p>
* @param externalSigning {@code true} if external signing should be performed
*/
public void setExternalSigning(boolean externalSigning)
{
this.externalSigning = externalSigning;
}
public boolean isExternalSigning()
{
return externalSigning;
}
}
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