[BNM] Multi password encryption

[Gary Broadbent]

Hi BNMers,

Does anybody know of an encryption method that fits the following criteria:

1. Multi level passwords (each password holds an incremental chunk of data)
2. ascii based encryption output (once content is encrypted, output must be 
acsii)
3. Open source, non proprietary (We need to integrate the source code into a 
website. It can be any language, I dont mind converting it)
4. Cant be based on a database. (The encrypted data should be transportable)

The basic idea is that I would enter a bunch of data with say 3 passwords. 
Each user would get a password. When user 1 enters his password, he only gets 
a subset of the encrypted data. User 2 enters his password and gets all the 
information user 1 does, plus another subset of the data. The third user 
enters his password and gets all the data

I dont want a bunch of nested encrypts, eg. user 2 and 3 must not have to 
enter user 1's and users 2's password.

Thanks for any help in advance.

Gary Stidston-Broadbent