/**
* Creates signature for data.
*
* @param alg Algorithm.
* @param prv Provider.
* @param key Private key.
* @param data Data.
* @return Signature.
* @throws GeneralSecurityException If any exception occurs while signature creation.
*/
public static byte[] createSignature(String alg, String prv, PrivateKey key, byte[] data)
throws GeneralSecurityException {
assert !F.isEmpty(alg);
assert !F.isEmpty(prv);
assert key != null;
assert data != null;
Signature sign = Signature.getInstance(alg, prv);
sign.initSign(key);
sign.update(data);
return sign.sign();
}
/**
* Verifies signature for data.
*
* @param alg Algorithm.
* @param prv Provider.
* @param key Public key.
* @param data Data.
* @param sign Signature.
* @return {@code true} if signature was verified, {@code false} - otherwise.
* @throws GeneralSecurityException If any exception occurs while verifying.
*/
public static boolean verifySignature(
String alg, String prv, PublicKey key, byte[] data, byte[] sign)
throws GeneralSecurityException {
assert !F.isEmpty(alg);
assert !F.isEmpty(prv);
assert key != null;
assert data != null;
assert sign != null;
Signature sign0 = Signature.getInstance(alg, prv);
sign0.initVerify(key);
sign0.update(data);
return sign0.verify(sign);
}