Write x509 certificate into PEM formatted string in java?

Question

Is there some high level way to write an X509Certificate into a PEM formatted string? Currently I\'m doing x509cert.encode() to write it into a DER formatted string, then ba

Answer 1

The following uses no big external libraries or possibly version-inconsistent sun.* libraries. It builds on judoman's answer, but it also chunks lines at 64 characters, as required by OpenSSL, Java, and others.

Import:

import javax.xml.bind.DatatypeConverter;
import java.security.cert.X509Certificate;
import java.io.StringWriter;

Code:

public static String certToString(X509Certificate cert) {
    StringWriter sw = new StringWriter();
    try {
        sw.write("-----BEGIN CERTIFICATE-----\n");
        sw.write(DatatypeConverter.printBase64Binary(cert.getEncoded()).replaceAll("(.{64})", "$1\n"));
        sw.write("\n-----END CERTIFICATE-----\n");
    } catch (CertificateEncodingException e) {
        e.printStackTrace();
    }
    return sw.toString();
}

(I would have just commented on judoman's answer, but I don't have enough reputation points to be allowed to comment, and my simple edit was rejected because it should have been a comment or an answer, so here's the answer.)

If you want to write straight to file, also import java.io.FileWriter and:

FileWriter fw = new FileWriter(certFilePath);
fw.write(certToString(myCert));
fw.close();