Almost all security systems in the modern world rely on a shared secret (password) system of some kind. The premise is that no-one other than the account holder knows the secret, so anyone who knows the secret must be the account holder!

Is there a basis in Halacha for using a piece of secret information to establish credibility (נאמנות)? I am looking for answers based on the rules of נאמנות only which do not rely on extra agreements between the parties.

Here are a few example cases where this would make a difference:

  1. A Jewish bank offering online money transfer to Jewish customers. What if the customer claims he never signed on and requested the money transfer?
  2. Sending online payments to a Jewish vendor. What if the vendor claims you sent it to the wrong place?
  3. Trusting a Psak from an authority which is already נאמן. For example, if I receive an e-mail from a someone claiming to be R' Chaim Kanievsky שליט''א (or his agent) and I want to verify it. (You can use secure hashes to verify identity, they work like passwords).
  4. ... lots more
  • 1
    Can you give an example where this would be useful?
    – Double AA
    Mar 25, 2015 at 18:50
  • 1
    Why would you think they can't? The customer agreed to those terms of service presumably
    – Double AA
    Mar 25, 2015 at 18:55
  • 1
    @DoubleAA How about shelichus for a get, or similar?
    – Ypnypn
    Mar 25, 2015 at 18:58
  • 1
    Ploni, welcome to Mi Yodeya, and thanks for bringing your question here! As @DoubleAA indicates, it will be a much stronger question if you edit in some suggestions for realms of Halacha or particular cases in which password-based trust may matter. Please consider registering your account, which will give you access to more of the site's features.
    – Isaac Moses
    Mar 25, 2015 at 19:00
  • 2
    Related: judaism.stackexchange.com/q/37913 and judaism.stackexchange.com/q/36924
    – msh210
    Mar 25, 2015 at 19:05


You must log in to answer this question.

Browse other questions tagged .