[tor-bugs] #19317 [Metrics/CollecTor]: Sanitize TCP ports in bridge descriptors

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#19317: Sanitize TCP ports in bridge descriptors
-------------------------------+------------------------------
 Reporter:  karsten            |          Owner:
     Type:  enhancement        |         Status:  needs_review
 Priority:  Medium             |      Milestone:
Component:  Metrics/CollecTor  |        Version:
 Severity:  Normal             |     Resolution:
 Keywords:                     |  Actual Points:
Parent ID:                     |         Points:
 Reviewer:                     |        Sponsor:
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Comment (by iwakeh):

 Replying to [comment:5 karsten]:
 > .... `H(...)[:2] / 2^2 + 2^15 + 2^15`.
 should be `2^15 + 2^14` as it is in both html and java code. The latter
 might be more readable when using java7 features, i.e.

 {{{
 #!java
 int hashedPort =
  ((((hashInput[0] & 0b1111_1111) << 8) | (hashInput[1] & 0b1111_1111)) >>
 2)
       | 0b1100_0000_0000_0000;
 }}}

 How much privacy is actually gained with all this?
 Reducing the range gives some privacy, but how much given that the
 original ports are not randomly distributed in their range?
 Just point me to an appropriate doc, if this question seems trivial.

--
Ticket URL: <https://trac.torproject.org:443/projects/tor/ticket/19317#comment:6>
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