Merge Secret Keeper Application

[chenchanglew]

What this PR does / why we need it:
Create a new application for rollback attack scenario, namely Secret Keeper

Special notes for your reviewer:
Secret Keeper has 5 functions.

• InitSecretKeeper:
  • This function will initialize the key "AUTH_LIST_KEY" with value ["Alice", "Bob"] and key "SECRET_KEY" with value "DefaultSecret".
  • This function should only be called once when the application started.
  • Of course a malicious user can call this function to reset the value, but this we will assume this is not what an attacker would want to achieve.
• RevealSecret:
  • This function allow users that in the Authlist ("AUTH_LIST_KEY") able to reveal the value of secret stored under key "SECRET_KEY".
• LockSecret:
  • This function allow users that in the Authlist ("AUTH_LIST_KEY") able to store a new value of secret under key "SECRET_KEY".
  • The old value will be replaced.
• AddUser:
  • This function allow users that in the Authlist ("AUTH_LIST_KEY") able to add a new user to the Authlist.
  • Then the new user can now perform the following four functions (RevealSecret, LockSecret, AddUser, RemoveUser)
• RemoveUser:
  • This function allow users that in the Authlist ("AUTH_LIST_KEY") able to add remove an existing user off the Authlist.
  • Then the removed user can no longer able to perform the following four functions (RevealSecret, LockSecret, AddUser, RemoveUser)

Example using fpc-simple-client:

./fpcclient invoke initSecretKeeper
./fpcclient query revealSecret Alice
./fpcclient invoke lockSecret Bob NewSecret
./fpcclient query revealSecret Alice
./fpcclient invoke removeUser Alice Bob
./fpcclient query revealSecret Alice
./fpcclient query revealSecret Bob  // (will failed)
./fpcclient invoke addUser Alice Bob
./fpcclient query revealSecret Bob // (will success)