Questions about encryption

[Gustaf Liljegren]

I found myself needing encryption for a file with user info, but know 
almost nothing about the principles, so here's some very basic questions 
about encryption in Python. Links for getting started with encryption 
understanding is also appreciated. But no specs please. :-)

1. The Library describes how to encrypt strings using for example the md5 
and sha modules, but I find no information about decrypt the same strings! 
The rotor module seem to handle decryption too, but also seem more 
complicated to use.

2. Is it possible to encrypt a file from one script and decrypt it from 
another?

3. The two scripts in question use dictionaries as datatypes internally. 
Does an encyption feature suggest a choise of another datatype, or can the 
conversion between string <-> dictionary be easily accomplished?

Regards,

Gustaf Liljegren, Sweden