Android key pair generation in format with -----BEGIN PUBLIC KEY----- and ending with -----END PUBLIC KEY-----

Question

I am generating my keypair like this:

 KeyPair kp = null;
 KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
 kpg.initialize(2048);
 kp = kpg.generateKeyPair();

and I get my public key like this:

    PublicKey publicKey = kp.getPublic();
    byte[] publicKeyBytes = publicKey.getEncoded();
    String publicKeyEncoded = new String(Base64.encode(publicKeyBytes, Base64.DEFAULT));

What I get in return is perfectly fine key, but the server is accepting keys in the format in which I need to have starting and ending tags

-----BEGIN PUBLIC KEY-----
-----END PUBLIC KEY-----

Should I add these tags myself in the encoded key or there is some method/format in Java that gives me the key in the following format?

Have you checked this question: https://stackoverflow.com/questions/12749858/rsa-public-key-format?rq=1 — Turtle, Aug 30 '17 at 09:54
@RanjithKumar I have concatenated the string(key) with -----BEGIN PUBLIC KEY----- & -----END PUBLIC KEY----- Tags — Shubham, Jun 14 '18 at 05:21

score 1 · Answer 1 · answered Mar 28 '19 at 11:37

Post the next answer because the headline and footline strings fails when these don't have the right characters:

public class KeyManager {

    public static final String TAG = KeyManager.class.getSimpleName();

    public static String getPublicKey(){
        KeyPair kp = generateRSAKeys();
        assert kp != null;
        PublicKey publicKey = kp.getPublic();
        String key = encodeKey(publicKey.getEncoded());
        return addHeaders(key);  // --> ADDED HEADERS FOR SERVER COMPATIBILITY
    }

    private static String getPrivateKey(){
        KeyPair kp = generateRSAKeys();
        assert kp != null;
        PrivateKey privateKey = kp.getPrivate();
        return encodeKey(privateKey.getEncoded());
    }

    private static KeyPair generateRSAKeys() {
        try {
            KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
            kpg.initialize(2048);
            return kpg.generateKeyPair();

        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG,"[ENCRYPT] NoSuchAlgorithmException error: ");
            e.printStackTrace();
            return null;

        } catch (Exception e) {
            Log.e(TAG,"[ENCRYPT] generateRSAKeys error: ");
            e.printStackTrace();
            return null;
        }
    }

    private static String addHeaders(String key){
        String headline = "-----BEGIN PUBLIC KEY-----\n";
        String footline = "-----END PUBLIC KEY-----\n";
        return headline+key+footline;
    }

    private static String encodeKey(byte[] keyBytes) {
        return new String(Base64.encode(keyBytes, Base64.DEFAULT));
    }
}

Android key pair generation in format with -----BEGIN PUBLIC KEY----- and ending with -----END PUBLIC KEY-----

1 Answers1