/** @throws InvalidKeyException if the specified key cannot be used to initialize any provider. */
private static Engine.SpiAndProvider tryAlgorithm(Key key, Provider provider, String algorithm)
throws InvalidKeyException {
if (provider != null) {
Provider.Service service = provider.getService(SERVICE, algorithm);
if (service == null) {
return null;
}
return tryAlgorithmWithProvider(null, service);
}
ArrayList<Provider.Service> services = ENGINE.getServices(algorithm);
if (services == null || services.isEmpty()) {
return null;
}
boolean keySupported = false;
for (Provider.Service service : services) {
if (key == null || service.supportsParameter(key)) {
keySupported = true;
Engine.SpiAndProvider sap = tryAlgorithmWithProvider(key, service);
if (sap != null) {
return sap;
}
}
}
if (!keySupported) {
throw new InvalidKeyException("No provider supports the provided key");
}
return null;
}
/**
* Returns a {@code Set} of all registered algorithms for the specified cryptographic service.
* {@code "Signature"}, {@code "Cipher"} and {@code "KeyStore"} are examples for such kind of
* services.
*
* @param serviceName the case-insensitive name of the service.
* @return a {@code Set} of all registered algorithms for the specified cryptographic service, or
* an empty {@code Set} if {@code serviceName} is {@code null} or if no registered provider
* provides the requested service.
*/
public static Set<String> getAlgorithms(String serviceName) {
Set<String> result = new HashSet<String>();
// compatibility with RI
if (serviceName == null) {
return result;
}
for (Provider provider : getProviders()) {
for (Provider.Service service : provider.getServices()) {
if (service.getType().equalsIgnoreCase(serviceName)) {
result.add(service.getAlgorithm());
}
}
}
return result;
}
private static Engine.SpiAndProvider tryAlgorithmWithProvider(Key key, Provider.Service service) {
try {
if (key != null && !service.supportsParameter(key)) {
return null;
}
Engine.SpiAndProvider sap = ENGINE.getInstance(service, null);
if (sap.spi == null || sap.provider == null) {
return null;
}
if (!(sap.spi instanceof SignatureSpi)) {
return null;
}
return sap;
} catch (NoSuchAlgorithmException ignored) {
}
return null;
}
// Access to Security.getAliases()
public List<String> getAliases(Provider.Service s) {
return s.getAliases();
}
