I see what your saying, and looked a little closer to the indictment.
However, I don't think it still quite the same thing as a key/lock. A password can contain information and as a Assange could have just been trying to see the password contained any useful information. What if the password was something like "I.like.blank" and it's known who the administrator of the computer system was. A hash is just a piece of information.
Like the details are not entirely clear in the indictment. The only thing clear is that he was given a hash. The indictment does not say if trying to guess the password hash was going to be used to login into the system. Although, it seems like that what the indictment assumes, and without a full transcript of the conversation I feel the indictment is pretty weak.
However, after reading there are multiple things that make really doubt who ever wrote that has any idea what they are talking about.
For instance: Manning did not have administrative-level privileges, and used special software, namely a Linux operating system, to access the computer file and obtain the portion of the password provided to Assange.
I was unaware linux was special software....