"Password" variable

I'm working with a script that will access SVN server by different users.
Problem is:
- There'll be midnight build
- There is no "master" user and password
- I don't want to prompt for every user and password everytime
- I don't want to store user and password in text file
- Using script to encrypt a decrypted text isn't very secure, since script can be easily seen and manipulated
- If I use variable, simple printing in script can easily reveals the password. 

It'll be great if there's a secure "password" variables that is not easily seen.