How to get the java.security.PrivateKey object from RSA Privatekey.pem file?

Question

I have a RSA private key file (OCkey.pem). Using java i have to get the private key from this file. this key is generated using the below openssl command. Note : I can\'t c

Answer 1

Make sure the privatekey is in DER format and you're using the correct keyspec. I believe you should be using PKCS8 here for the privkeybytes

Firstly, you need to convert the private key to binary DER format. Heres how you would do it using OpenSSL:

openssl pkcs8 -topk8 -inform PEM -outform DER -in private_key.pem -out private_key.der -nocrypt

Finally,

public static PrivateKey getPrivateKey(String filename) throws Exception {

        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f);
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int) f.length()];
        dis.readFully(keyBytes);
        dis.close();

        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(spec);
    }