Are the password cracking methods used in the film remotely realistic?

Prompted by this question Why are computer hackers shown to either be geniuses, or show them doing it in fantastic ways? I trawled my brain to find any examples I could remember of anything resembling realistic hacking or cracking in a movie.

I struggled.

Then I remembered some scenes from the entertaining Sneakers where things didn't seem like magic and looked like they took some effort. Ironically, given the question, the password cracking was necessary

to access a new technology that would enable easy cracking of passwords.

(It's an old movie but I didn't want to spoil a key plot development.)

So my question is this: were the techniques deployed in Sneakers realistic? And, for completeness, what were they? (I haven's seen it for a while)