[tor-bugs] #22029 [Core Tor/Tor]: Allow ed25519 keys to be banned in the approved-routers file

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#22029: Allow ed25519 keys to be banned in the approved-routers file
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  neel
     Type:  enhancement                          |         Status:
                                                 |  needs_review
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.4.1.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  034-triage-20180328,                 |  Actual Points:
  034-removed-20180328                           |
Parent ID:                                       |         Points:  1
 Reviewer:  asn                                  |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by asn):

 Hey neel,

 this is much better, but I still don't quite agree with this code block:
 {{{
 +    if (!is_valid_key ||
 +        base16_decode(digest_tmp, sizeof(digest_tmp), fingerprint,
 +                      HEX_DIGEST_LEN) != sizeof(digest_tmp) ||
 +        digest256_from_base64(digest256_tmp, fingerprint) < 0) {
 +      log_notice(LD_CONFIG,
 +                 "Invalid fingerprint (nickname '%s', "
 +                 "fingerprint %s). Skipping.",
 +                 nickname, fingerprint);
 +      continue;
 +    }
 }}}

 I don't understand why we do an extra decode (either the `base16_decode`
 or the `digest256_from_base64()` is not useful at this point) when we
 already know the type of the key?

 I coded an alternative approach in:
 https://github.com/torproject/tor/pull/810

 Let me know if you like it and feel free to put it in merge_ready if so.

 Thanks! :)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22029#comment:26>
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