The steps shown in "password generating logic" would be a big effort.
But I think for an easier szenario:
1) I create a specific down/upload folder (and user account/password)
2) Then I send this information to the customer.
3) After the access at any time the password is implicit reseted
Effort for me:
- I dont have to analyse the logfiles a.s.a.p/online
- I know, that the files in the folders cannot be read/uploaded twice, or the account information cannot be used by collegues,...
- I can read/clean the folder offline(!), knowing that no one can reread/reaccess the files from outside
- After the "cleaning" of the folder it can be reused with a new password for a next customer ...