import org.bouncycastle.crypto.params.DSAKeyParameters; //导入依赖的package包/类
/**
 * Get the key size of a key represented by key parameters.
 * 
 * @param keyParams The key parameters
 * @return The key size, {@link #UNKNOWN_KEY_SIZE} if not known
 */
public static int getKeyLength(AsymmetricKeyParameter keyParams)
{
	if (keyParams instanceof RSAKeyParameters)
	{
		return ((RSAKeyParameters) keyParams).getModulus().bitLength();
	}
	else if (keyParams instanceof DSAKeyParameters)
	{
		return ((DSAKeyParameters) keyParams).getParameters().getP().bitLength();
	}
	else if (keyParams instanceof DHKeyParameters)
	{
		return ((DHKeyParameters) keyParams).getParameters().getP().bitLength();
	}
	else if (keyParams instanceof ECKeyParameters)
	{
		// TODO: how to get key length from these?
		return UNKNOWN_KEY_SIZE;
	}

	LOG.warning("Don't know how to get key size from parameters " + keyParams);
	return UNKNOWN_KEY_SIZE;
}