Hockeypuck: Open source GPG keyserver

Speaker:Casey Marshall
Date:2013-02-24
Site:http://launchpad.net/hockeypuck

Intro

  • Public Key Servers to validate identities

  • GnuPG Keyserver example:

    gpg --keyserver ketserver.foo.com --search-keys me@foo.com

  • Secure email (SMIME), e.g. Thunderbird + enigmail plugin

  • Verifying software packages (apt, yum, App Store, etc.)

  • OS packages:

    sudo apt-key adv --keyserver keyserver.foo.com --recev 7F0CEB10

  • Search by name:

    gpg --keyserver ks.foo.com --search-keys barack obama
gpg: searching for "barack obama" from hkp server ks.foo.com

What is a Key Server?

  • HKP (HTTP Keyserver Protocol) - RESTful HTTP API
  • Read Ops
    • /pks/lookup?
    • ``search={kw} - fingerprint or shortened suffix
    • op=get
    • op=index, op=vindex
  • Write Ops
    • /pks/add
    • Merge key material (new sigs, revocations)
  • PKS (SMTP Protocol)

SKS: Sync Key Server

  • Berkley DB storage
  • Global distributed db
  • SKS global pool, highly distributed and sharded
  • Makes it difficult for anyone to control or forge a key

Gazzang zTrustee

  • Commercial KS, closed source
  • Opaque object store
  • “You get what you put”
  • Built on OpenPGP
  • Cannot decrypt
  • Multi-factor authorization (email or API)

Hockeypuck

  • Written in go
    • Simplicity, modularity
    • “Static duck typing”
    • Concurrency
  • Backed by MongoDB
  • Indexd by reversed fingerprint
  • Full-text search
  • Pretty fast: 2M keys in ~24 hours
    • OpenPGP v3 sigs not yet supported
    • Database is the bottleneck (thanks MongoDB)

PGP Self-Signatures

  • Signature-checking “optional”?
  • If you don’t check it, others can add attributes (BAD)
  • GPG will throw it out because it is not self-signed and doesn’t match

SKS Reconciliation

  • Distributed db
  • Reperesent db as polynomial, diffs as a ratio
  • Share sample points and ... interpolate??
    • See: Conflux (github cmars/conflux)
    • ...not just for keys anymore!
  • Content-addressable things (digitally sign all the things)
    • Messages, images, contacts
    • File/folder sync
    • Location servers

Building Trust

  • Add multiple factos to a key exch
    • rendezvous for key exchange
    • identites beyond email (e.g. facebook)
  • Keep keyservers distributed
    • Promote diversity, avoid monoculture

Identity Management

  • Certify yourself
    • Provide id to ks
    • Sign something, upload to an account you control
    • Link a public key to OpenID or OAuth accounts?
  • Hide yourself
    • From all searches?
    • Unless search request is signed by X keys?
  • Delete yourself!
    • Store this key on zero or more keyservers
    • “Hey, this key server burned me!”
  • Decide for yourself
    • Group-level visibility, certifications

SSH

Host Authenticity

  • Trust established the first time you connect (accepting host key)
  • SSHFP DNS records
  • What about cloud?
  • J-PAKE mediated by Hockeypuck
    • Secure remote handshaking by intermediary
    • Authenticate key out-of-band!
  • SSH, shell script wrappers and Hockeypuck

User Authenticity

  • Some SSH key server you might not know...
    • Launchpad (trusted users can see each others SSH keys!)
    • GitHub
  • ssh-import-id gh:cmars lp:kirkland
  • Add authenticity with PGP
    • ssh-import-id pgp:0x44A2D1Db
    • “Server-side Monkeysphere”?

Certificate Authorities

  • ONE KEY TO RULE THEM ALL AND IN THE DARKNESS SIGN THEM (lulz)
  • convergence.io protocol, act as notary
  • PGP sigs on certs
  • “Too big to fail?”
    • Translation: “Brings failure to others”
    • Or: “Youre’ not trying hard enough”