Xianda Ke created PIG-4929:
------------------------------

             Summary: improve factory api for constructing CryptoRandom & 
CryptoCipher
                 Key: PIG-4929
                 URL: https://issues.apache.org/jira/browse/PIG-4929
             Project: Pig
          Issue Type: Bug
            Reporter: Xianda Ke


currently, the client code to construct a CryptoRandom or CryptoCipher looks 
like this:
{code}
// code snippet (a)
Properties props = new Properties();
props.setProperty(
     ConfigurationKeys.COMMONS_CRYPTO_SECURE_RANDOM_CLASSES_KEY,
                OpensslCryptoRandom.class.getName());
CryptoRandom random = CryptoRandomFactory.getCryptoRandom(props);
{code}
or using configuration file, it looks like :

{code}
# config file
secure.random.classes="org.apache.commons.crypto.random.OpensslCryptoRandom"
{code}
{code}
// code snippet (b)
{
    Properties props = loadMyApplicationConfig();
    // ...
}
 
{
    // bussiness logic ...
    CryptoRandom random = CryptoRandomFactory.getCryptoRandom(props);
    // ...
    CryptoCipher cipher = CryptoCipherFactory.getInstance(transform, props);
}
{code}
disadvantages:
1. if client user just want use openssl engine,  trivial stuff in code snippet 
(a). it looks annoying.
2. Client user has to use the long long config key string such as  
"COMMONS_CRYPTO_SECURE_RANDOM_CLASSES_KEY" or full name of classes
 Client user has to read source to  learn how to config the properties. 
3. the implementation classes such as JavaCryptoRandom,  OsCryptoRandom and 
JavaCryptoRandom are public.
it would be hard to change library implementation in future.

if we just *use a enum (RandomProvider or CryptCipherProvider)*
{code}
// code snippet (c)
// client code looks simple and elegant now:
//RandomProvider.OS or RandomProvider.JAVA
CryptoRandom random = 
CryptoRandomFactory.getCryptoRandom(RandomProvider.OPENSSL);
{code}
still, client user can use configuration file
{code}
# config file
RandomProvider="OPENSSL"
CryptCipherProvider="JCE"
{code}
{code}
// code snippet 
{
    Properties props = loadMyApplicationConfig();
    RandomProvider randProvider = RandomProvider.valueOf(props.getProperty(p1));
    CryptoProvider cryptoRrovider 
=RandomProvider.valueOf(props.getProperty(p1));
}
{
    // bussiness logic ...
    CryptoRandom random = CryptoRandomFactory.getCryptoRandom(randProvider);
    // ...
    CryptoCipher cipher = CryptoCipherFactory.getInstance(transform, 
cryptoRrovider);
}
{code}
advantages:
1. Simpler API.  snippet (c) is simpler than snippet (a).  
2. Modern IDE will hint that CryptoRandomFactory.getCryptoRandom()  need a enum 
type (RandomProvider). client user do NOT have to search the long  key string 
such as "COMMONS_CRYPTO_SECURE_RANDOM_CLASSES_KEY". Modern IDE will tell client 
user how to config
3. we don't have to expose the implementation classes as public



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