Question

I am implementing SSL certificate and key in my application. I have created private key using CertAndKeyGen class. I am trying to encrypt the private key with a password, which I have achieved it through PBE and Cipher class. I would like to write the encrypted private key into a file in PEM format. I tried with FileOutputStream which is working but PrintWriter is not working as excepted.

Below is my code,

    final CertAndKeyGen keypair = new CertAndKeyGen("RSA", "SHA1WithRSA", null);
    keypair.generate(1024);
    final PrivateKey privKey = keypair.getPrivateKey();
    byte[] encodedprivkey = privKey.getEncoded();
    String MYPBEALG = "PBEWithSHA1AndDESede";
    String password = "test123";
    int count = 20;// hash iteration count
    Random random = new Random();
    byte[] salt = new byte[8];
    random.nextBytes(salt);
    PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, count);
    PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());
    SecretKeyFactory keyFac = SecretKeyFactory.getInstance(MYPBEALG);
    SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);
    Cipher pbeCipher = Cipher.getInstance(MYPBEALG);
    // Initialize PBE Cipher with key and parameters
    pbeCipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);
    // Encrypt the encoded Private Key with the PBE key
    byte[] ciphertext = pbeCipher.doFinal(encodedprivkey);
    // Now construct  PKCS #8 EncryptedPrivateKeyInfo object
    AlgorithmParameters algparms = AlgorithmParameters.getInstance(MYPBEALG);
    algparms.init(pbeParamSpec);
    EncryptedPrivateKeyInfo encinfo = new EncryptedPrivateKeyInfo(algparms,ciphertext);
    byte[] encryptedPkcs8 = encinfo.getEncoded();

    // Now I am writing the encrypted private key into a file.
    // Using FileOutputStream 

    FileOutputStream out = new FileOutputStream("usingOutEncrypedPrivkey");
    out.write(Base64.encodeBase64(encryptedPkcs8, true));
    out.flush();
    out.close();

    // Using PrintWriter 
    PrintWriter pw = new PrintWriter("usingPwEncryptedPrivKey");
    pw.println("-----BEGIN "+ privKey.getAlgorithm() + " PRIVATE KEY-----");
    pw.println(Base64.encodeBase64(encryptedPkcs8));
    pw.println("-----END "+ privKey.getAlgorithm() +" PRIVATE KEY-----");
    pw.close();

Below are the files saved,

    usingOutEncrypedPrivkey  // Which was saved using FileOutputStream

    MIICoTAbBgoqhkiG9w0BDAEDMA0ECL4xgraq2hXxAgEUBIICgFENaB8EA/kR0ymSC8vcyj1fNFbP
    iR+mXkBk7aH3eF7fpP8yqCvtN0/0VqHi/w/Z2CLgiib2s/zuiVPtWI8vsRRPXmD9PYxZp3ilLpD4
                            .....
                            .....   
    9nH8HdQf584c3sKYEErDQvJR2SmbUPtNq4cB6ocUuiOTztBqRXAHeaWavnqHFxHUT7c=


    usingPwEncryptedPrivKey  // Which was saved using PrintWriter
   -----BEGIN RSA PRIVATE KEY-----
   [B@19e3118a
   -----END RSA PRIVATE KEY-----

Why is the PrintWriter writing as “[B@19e3118a”, instead of the bytes like FileOutputStream. I want to use PrintWriter since I want to make use of PrintWriter.println() function. Please help me out. Thanks in advance.

Answer 1

• OutputStream.write(byte[]) writes the bytes as binary data.
• PrintWriter.print(byte[]) calls toString() on the array and writes out the result. The [B@19e3118a is the toString() representation of your array.

Given that the string only contains ASCII characters, you could use String(byte[]) on your array, and print the result.

Alternatively, if you’re using the Apache Commons Base64 class, you should simply use the encodeBase64String() method instead of encodeBase64() [Thanks @SimonC].