cryptography - Java Retrieve the actual value of the public key from the KeyPair object

Question

I wanted to ask how to retrieve the actual values of the private and public keys from the KeyPair object because i need to export them and save in a database.

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024);
KeyPair keyPair = kpg.genKeyPair();

System.out.println("Public key " + keyPair.getPublic());
System.out.println("Private key " + keyPair.getPrivate());

The output is:

Public key Sun RSA public key, 1024 bits
  modulus: 105712092415375085805423498639048173422142354311030811647243014925610093650322108853068042919471115278002432342007597147610508132502035047888382465733153739247741208519707861808073276783311634229563965825609200080862631487160732889423591650215084096832366499080850540875321197564283324922935557797293830551071
  public exponent: 65537
Private key sun.security.rsa.RSAPrivateCrtKeyImpl@35e71

Answer 1

You can simply downcast to RSAPrivateKey and RSAPublicKey. Once you've done that you can access the methods of these classes.

RSAPublicKey pubKey = (RSAPublicKey) keyPair.getPublic());
BigInteger modulus = pubKey.getModulus();

etc.