Getting the Digital Signature Algorithm (DSA) Parameters of a Key Pair
The DSA requires three parameters to create a key pair --- the
prime (P), the subprime (Q), and the base (G). These three values are
used to create a private key (called X) and a public key (called Y).
This example creates a DSA key pair with provider-supplied
default values for P, Q, and G, and then retrieves the default values.
try {
// Generate a 1024-bit Digital Signature Algorithm (DSA) key pair
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
keyGen.initialize(1024);
KeyPair keypair = keyGen.genKeyPair();
DSAPrivateKey privateKey = (DSAPrivateKey)keypair.getPrivate();
DSAPublicKey publicKey = (DSAPublicKey)keypair.getPublic();
// Get p, q, g; they are the same for both private and public keys
DSAParams dsaParams = privateKey.getParams();
BigInteger p = dsaParams.getP();
BigInteger q = dsaParams.getQ();
BigInteger g = dsaParams.getG();
// Get the private key's X
BigInteger x = privateKey.getX();
// Get the public key's Y
BigInteger y = publicKey.getY();
} catch (NoSuchAlgorithmException e) {
}
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