crush depth

Signing Issues

I'm having trouble deploying packages to Maven Central. The repository claims that it cannot validate the signatures I provide. I've filed a bug but haven't gotten a response. I'm wondering if it's down to me switching to Curve25519 PGP keys...

New PGP Keys

New PGP keys have been published.

Fingerprint                                       | UID
B84E 1774 7616 C617 4C68 D5E5 5C1A 7B71 2812 CC05 | Mark Raynsford (2018 personal)
F8C3 C5B8 C86A 95F7 42B9 36D2 97E0 2011 0410 DFAF | (2018 release-signing)
Verifying Again

See the the previous blog post:

$ gpg --recv-keys 8168DAE22B15D3EDC722C23D0F15B7D06FA80CB8
$ wget -r
$ cd
$ gpg < checksum.asc | sha512sum --check


How To Verify

This blog was designed to be verifiable:

$ gpg --recv-keys 8168DAE22B15D3EDC722C23D0F15B7D06FA80CB8
$ wget -r
$ find -name '*.asc' -exec gpg --verify {} \;

Note that the 8168DAE22B15D3EDC722C23D0F15B7D06FA80CB8 key ID assumes you're reading this in 2017. By the time 2018 comes around, this blog will be signed with a new key (and a new one for each passing year).

Possible points of failure:

  1. A malicious actor gets the remote keyserver to serve a different key than the one with fingerprint 8168DAE22B15D3EDC722C23D0F15B7D06FA80CB8. Does gnupg verify that a received key had the fingerprint that the user specified on the command line? What if the user specified my name and key comment instead of a fingerprint? The actor at this point might be able to convince you that the signatures on files on are invalid. It might be able to convince you that its own key is mine.

  2. A malicious actor modifies the files and signatures when wget downloads them. The actor can't generate valid signatures for the key 8168DAE22B15D3EDC722C23D0F15B7D06FA80CB8 (unless it can break RSA), but it can try to convince you that its own key is actually my key and therefore have you trust that the data you're seeing is unmodified and was signed by me. If the actor managed to perform step 1 above, then you're completely compromised.

  3. A malicious actor removes some of the signatures. If you didn't know exactly how many pages there should be, you'd not notice if gpg didn't verify one of them.

Step 1 has no technical solution; you need to verify the keys you receive and check the signatures on those keys assuming they come from other keys that you trust. If you're lucky, there is a chain of signatures leading to a key that you do trust with certainty. I have yearly expiring keys, and I sign each new year's keys with the old keys. Unless my keys have been compromised yearly, there's a reasonable chance that the keys you see are mine!

Step 2 is partially mitigated by https, assuming that the actor doesn't have backdoor access to the CA issuing the certificate. The actor can have the CA issue a new certificate, redirect you to a server that the actor controls, decrypt the traffic, modify it, and then re-encrypt it. You'd never know anything was wrong.

Step 3 is manually mitigated by reading the posts by year page and checking that you have at least as many signatures as pages. I may start publishing a CHECKSUMS file that just contains signed SHA512 hashes of every file on the site.

I'm considering using keybase in addition to publishing PGP keys on the public keyservers. I don't do social media, so I'm not sure how much it'd apply to me. I do use GitHub heavily though.

New PGP Key
Hash: SHA512


Pushed a new key for signing commits in Android work. I'll still be
releasing new personal and release signing keys in January (and I'll
be switching to ed25519 keys from RSA).

E134 3512 A805 115A C1A0 1D15 C578 C3C0 C9B1 2BFF
Mark Raynsford (2018 android commit signing)