/**
* Sets the mode of a {@link javax.crypto.CipherSpi} instance.
*
* <p>Like {@link #getCipher(String)}, we're accessing a private API here, so me must work around
* the access restrictions
*
* @param cipherSpi the {@link javax.crypto.CipherSpi} instance
* @param mode the mode to set
* @throws Throwable if {@link javax.crypto.CipherSpi#engineSetPadding} throws
*/
private static void cipherSpiSetMode(final CipherSpi cipherSpi, final String mode)
throws Throwable {
final Method engineSetMode = getMethod(cipherSpi.getClass(), "engineSetMode", String.class);
engineSetMode.setAccessible(true);
try {
engineSetMode.invoke(cipherSpi, mode);
} catch (final InvocationTargetException e) {
throw e.getCause();
}
}
/**
* Replacement for JCA/JCE's {@link javax.crypto.Cipher#getInstance}. The original method only
* accepts JCE providers from signed jars, which prevents us from bundling our cryptography
* provider Bouncy Caster with the application.
*
* @param transformation the transformation to find an implementation for
*/
public static Cipher getCipher(final String transformation) {
try {
/* Split the transformation into algorithm, mode and padding */
final Matcher transformation_matcher =
s_transformation_pattern.matcher(transformation.toUpperCase());
if (!transformation_matcher.matches())
throw new RuntimeException("Transformation " + transformation + " is invalid");
final String algorithm = transformation_matcher.group(1);
final String mode = transformation_matcher.group(3);
final String padding = transformation_matcher.group(4);
final boolean isBareAlgorithm = (mode == null) && (padding == null);
/* Build the property values we need to search for. */
final String algorithmModePadding =
!isBareAlgorithm ? algorithm + "/" + mode + "/" + padding : null;
final String algorithmMode = !isBareAlgorithm ? algorithm + "/" + mode : null;
final String algorithmPadding = !isBareAlgorithm ? algorithm + "//" + padding : null;
/* Search the provider for implementations. We ask for more specific (i.e matching
* the requested mode and or padding) implementation first, then fall back to more
* generals ones which we then must configure for the mode and padding.
*/
final CipherSpi cipherSpi;
if (!isBareAlgorithm && (resolveProperty(Provider, "Cipher", algorithmModePadding) != null)) {
@SuppressWarnings("unchecked")
final Class<? extends CipherSpi> cipherSpiClass =
(Class<? extends CipherSpi>)
Class.forName(resolveProperty(Provider, "Cipher", algorithmModePadding));
cipherSpi = cipherSpiClass.newInstance();
} else if (!isBareAlgorithm && (resolveProperty(Provider, "Cipher", algorithmMode) != null)) {
@SuppressWarnings("unchecked")
final Class<? extends CipherSpi> cipherSpiClass =
(Class<? extends CipherSpi>)
Class.forName(resolveProperty(Provider, "Cipher", algorithmMode));
cipherSpi = cipherSpiClass.newInstance();
if (!isBareAlgorithm) cipherSpiSetPadding(cipherSpi, padding);
} else if (!isBareAlgorithm
&& (resolveProperty(Provider, "Cipher", algorithmPadding) != null)) {
@SuppressWarnings("unchecked")
final Class<? extends CipherSpi> cipherSpiClass =
(Class<? extends CipherSpi>)
Class.forName(resolveProperty(Provider, "Cipher", algorithmPadding));
cipherSpi = cipherSpiClass.newInstance();
if (!isBareAlgorithm) cipherSpiSetMode(cipherSpi, mode);
} else if (resolveProperty(Provider, "Cipher", algorithm) != null) {
@SuppressWarnings("unchecked")
final Class<? extends CipherSpi> cipherSpiClass =
(Class<? extends CipherSpi>)
Class.forName(resolveProperty(Provider, "Cipher", algorithm));
cipherSpi = cipherSpiClass.newInstance();
if (!isBareAlgorithm) {
cipherSpiSetMode(cipherSpi, mode);
cipherSpiSetPadding(cipherSpi, padding);
}
} else {
throw new RuntimeException(
"Provider "
+ Provider.getName()
+ " ("
+ Provider.getClass()
+ ") does not implement "
+ transformation);
}
/* Create a {@link javax.crypto.Cipher} instance from the {@link javax.crypto.CipherSpi} the provider gave us */
s_logger.info("Using SPI " + cipherSpi.getClass() + " for " + transformation);
return getCipher(cipherSpi, transformation.toUpperCase());
} catch (final RuntimeException e) {
throw e;
} catch (final Error e) {
throw e;
} catch (final Throwable e) {
throw new RuntimeException(
"Provider "
+ Provider.getName()
+ " ("
+ Provider.getClass()
+ ") failed to instanciate "
+ transformation,
e);
}
}