PemUtils.java

package org.keycloak.util;


import org.keycloak.util.Base64;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.cert.X509Certificate;

/**
 * Utility classes to extract PublicKey, PrivateKey, and X509Certificate from openssl generated PEM files
 *
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public final class PemUtils {
    static {
        BouncyIntegration.init();
    }

    private PemUtils() {
    }

    public static X509Certificate decodeCertificate(InputStream is) throws Exception {
        byte[] der = pemToDer(is);
        ByteArrayInputStream bis = new ByteArrayInputStream(der);
        return DerUtils.decodeCertificate(bis);
    }

    public static X509Certificate decodeCertificate(String cert) throws Exception {
        byte[] der = pemToDer(cert);
        ByteArrayInputStream bis = new ByteArrayInputStream(der);
        return DerUtils.decodeCertificate(bis);
    }


    /**
     * Extract a public key from a PEM string
     *
     * @param pem
     * @return
     * @throws Exception
     */
    public static PublicKey decodePublicKey(String pem) throws Exception {
        byte[] der = pemToDer(pem);
        return DerUtils.decodePublicKey(der);
    }

    /**
     * Extract a private key that is a PKCS8 pem string (base64 encoded PKCS8)
     *
     * @param pem
     * @return
     * @throws Exception
     */
    public static PrivateKey decodePrivateKey(String pem) throws Exception {
        byte[] der = pemToDer(pem);
        return DerUtils.decodePrivateKey(der);
    }

    public static PrivateKey decodePrivateKey(InputStream is) throws Exception {
        String pem = pemFromStream(is);
        return decodePrivateKey(pem);
    }

    /**
     * Decode a PEM file to DER format
     *
     * @param is
     * @return
     * @throws java.io.IOException
     */
    public static byte[] pemToDer(InputStream is) throws IOException {
        String pem = pemFromStream(is);
        return pemToDer(pem);
    }

    /**
     * Decode a PEM string to DER format
     *
     * @param pem
     * @return
     * @throws java.io.IOException
     */
    public static byte[] pemToDer(String pem) throws IOException {
        pem = removeBeginEnd(pem);
        return Base64.decode(pem);
    }

    public static String removeBeginEnd(String pem) {
        pem = pem.replaceAll("-----BEGIN (.*)-----", "");
        pem = pem.replaceAll("-----END (.*)----", "");
        pem = pem.replaceAll("\r\n", "");
        pem = pem.replaceAll("\n", "");
        return pem.trim();
    }


    public static String pemFromStream(InputStream is) throws IOException {
        DataInputStream dis = new DataInputStream(is);
        byte[] keyBytes = new byte[dis.available()];
        dis.readFully(keyBytes);
        dis.close();
        return new String(keyBytes, "utf-8");
    }
}