Encryption and protection

[Bill Vlahos]

I have a project where the data is stored in custom properties of 
multiple cards in a stack that also has the UI for the user. Access to 
the data by the user can be restricted by a password the user can set. 
I want to protect my code in the stack as well.

What are the options in 2.5 to keep the data and stack structure secure?

1. Will the password mechanism in 2.5 be sufficient to protect my code?
If not, what are the options?

2. I want to allow the user to access the initial card of the stack but 
require a password (that they can set) to access any other cards. 
Access should be granted for as long as the user has the stack open 
(like a lot of web pages).  Once the stack is closed, or on an 
openStack,  or the user wishes to lock it again, the lock should be in 
place.
Would it work to check the value of a variable, field contents on a 
card that is not the initial card, or some custom property somewhere to 
grant access to the destination card?

3. How strong is the encryption that is built into the locking stack 
password?
If it isn't strong enough, what other options are there?
The product has to work without requiring access to the Internet for 
public key/private key exchanges and the program needs to be able to 
save changes in a way that leaves the data file always protected.

4. Is doing this in a stack the right approach or would it be better to 
have a binary data file like more traditional programs? If a data file 
is the right way to go, how can that be protected?

Please let me know what you think.

Thanks,
Bill Vlahos