Example of reading and writing x509 certificate and RSA private keys encoded in PEM format using BouncyCastle 1.48 (new api)

PkiUtils.java

public class PkiUtils {
    public static final int MinPassPhraseLength = 4;

    public static List<?> readPemObjects(InputStream is, final String pphrase) 
            throws IOException {
        List<Object> list = new LinkedList<Object>();
        PEMParser pr2 = new PEMParser(new InputStreamReader(is));
        
        JcaPEMKeyConverter converter = new JcaPEMKeyConverter().setProvider("BC");
        JcaX509CertificateConverter certconv = new JcaX509CertificateConverter().setProvider("BC");
        
        while (true) {
            Object o = pr2.readObject();
            if (null == o)
                break; // done
            
            list.add(parsePemObject(o, pphrase, converter, certconv));
        }
        return list;
    }

    private static Object parsePemObject(Object o, 
                                         final String pphrase,
                                         JcaPEMKeyConverter converter, 
                                         JcaX509CertificateConverter certconv) {
        try {
            if (o instanceof PEMEncryptedKeyPair) {
                o = ((PEMEncryptedKeyPair)o).decryptKeyPair(new JcePEMDecryptorProviderBuilder().build(pphrase.toCharArray()));
            } else if(o instanceof PKCS8EncryptedPrivateKeyInfo) {
                InputDecryptorProvider pkcs8decoder = new JceOpenSSLPKCS8DecryptorProviderBuilder().build(pphrase.toCharArray());
                o = converter.getPrivateKey(
                    ((PKCS8EncryptedPrivateKeyInfo)o).decryptPrivateKeyInfo(pkcs8decoder));
            }
        } catch (Throwable t) { 
            throw new RuntimeException("Failed to decode private key", t);
        }

        if (o instanceof PEMKeyPair) {
            try {
                return converter.getKeyPair((PEMKeyPair) o);
            } catch (PEMException e) {
                throw new RuntimeException("Failed to construct public/private key pair", e);
            }
        } else if(o instanceof RSAPrivateCrtKey){
            RSAPrivateCrtKey pk = (RSAPrivateCrtKey) o;
            return makeKeyPair(pk);
        } else if (o instanceof X509CertificateHolder) {
            try {   
          return certconv.getCertificate((X509CertificateHolder) o);  
            } catch (Exception e) {
                throw new RuntimeException("Failed to read X509 certificate", e);
            }
        } else {
            // catchsink, should check for certs and reject rest?
          System.out.println("generic case  type " + o.getClass().getName());
            return o;
        }
    }
    /**
     * Writes certificate or private key in PEM format into given stream Private
     * key will be encrypted using 3des cipher with given password(password must
     * be 4+ long).
     * 
     * @param w {@link Writer}
     * @param obj instance of {@link PrivateKey} or {@link Certificate}
     * @param password password
     * @throws IOException
     */
    public static void writePem(Writer w, Object obj, String password)
            throws IOException {
        writePem(w, obj, password, true);
    }

    static void writePem(Writer w, Object obj, String password, boolean closeStream)
            throws IOException {
        PEMWriter pw = null;
        try {
            pw = new PEMWriter(w);
            if (obj instanceof PrivateKey) {
                if (null == password ||
                    password.length() < MinPassPhraseLength)
                    throw new IllegalArgumentException(
                            "Private key encryption password must be no less than " +
                                    MinPassPhraseLength + " characters");
                pw.writeObject(obj, "DES-EDE3-CBC", password.toCharArray(),
                        SecureRandom.getInstance("SHA1PRNG"));
            } else
                pw.writeObject(obj);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } finally {
            if (null != pw && closeStream)
                pw.close();
        }
    }
}

You've not elected to put the import statements into the gist, which makes it much harder to use. there's even a static method imported and I have no idea where from.