qaul Security Number

[MathJud]

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To verify the public keys of the users, create a security number, analog as the Signal messenger does it.

Info & Questions

• Signal blog
  • https://signal.org/blog/safety-number-updates/
  • Security Number: 12 Groups of 5 Digits (= 12*2Bytes = 24bytes)
• SHA-512 hash iterated 5200 times
  • https://security.stackexchange.com/questions/195761/why-iterate-5200-times-when-computing-safety-numbers-in-signal

Algorithm

• Order the two public keys
  • smaller key & higher key
• create SHA-512 hash over the keys:
  • repeat step for 5200 times of this hash result
    • add the public keys each time to the hash result and create a new hash-512 out of it.
  • do this operation in an own async thread
• convert hash to number blocks:
  • still to discuss
  • most probably: in bytes & as a string.

RPC Communication

router/users.proto

SecurityNumberRequest

• User ID for the user of which we want the security number

SecurityNumberResponse

• user ID
• security number