Extract multiple X.509 certificates from PEM-formatted file in Java

Question

I have a method which extracts a X.509 certificate from a given PEM-formatted file, using the bouncycastle library.

Imports:

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter;
import org.bouncycastle.openssl.PEMParser;

Method:

/**
 * Reads an X509 certificate from a PEM file.
 *
 * @param certificateFile The PEM file.
 * @return the X509 certificate, or null.
 * @throws IOException if reading the file fails
 * @throws CertificateException if parsing the certificate fails
 */
public static X509Certificate readCertificatePEMFile(File certificateFile) throws IOException, CertificateException {
    if (certificateFile.exists() && certificateFile.canRead()) {
        try (InputStream inStream = new FileInputStream(certificateFile)) {
            try (PEMParser pemParser = new PEMParser(new InputStreamReader(inStream))) {
                Object object = pemParser.readObject();
                if (object != null && object instanceof X509CertificateHolder) {
                    return new JcaX509CertificateConverter().getCertificate( (X509CertificateHolder)object );
                }
            }
        }
    }
    return null;
}

This works well for "normal" certificate files, eg a server certificate. If I have a CA chain certificate file, containing multiple certificates, how could I achieve extracting all certificates from this file (the method shown only extracts the first certificate in the file).

Answer 1

Try this code, it handles multiple certificates and Private key entry im PEM file

Security.addProvider(new BouncyCastleProvider());
JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider("BC");
while((object = pemParser.readObject())!=null)
{
    if(object instanceof X509CertificateHolder)
    {
        X509Certificate x509Cert = (X509Certificate) new JcaX509CertificateConverter().getCertificate((X509CertificateHolder) object);
    }
    else if(object instanceof PEMEncryptedKeyPair)
    {
        if(password==null) throw new IllegalArgumentException("Password required for parsing RSA Private key");

        PEMDecryptorProvider decProv = new JcePEMDecryptorProviderBuilder().build(password.toCharArray());
        converter.getKeyPair(((PEMEncryptedKeyPair) object).decryptKeyPair(decProv));
    }
    else if(object instanceof PEMKeyPair)
    {
        converter.getKeyPair((PEMKeyPair) object);
    }     
}