2. OpenPGP Keys for FreeBSD

Cryptographic keys conforming to the OpenPGP (Pretty Good Privacy) standard are used by the FreeBSD project to authenticate committers. Messages carrying important information like public SSH keys can be signed with the OpenPGP key to prove that they are really from the committer. See PGP & GPG: Email for the Practical Paranoid by Michael Lucas and http://en.wikipedia.org/wiki/Pretty_Good_Privacy for more information.

2.1. Creating a Key

Existing keys can be used, but should be checked with doc/head/share/pgpkeys/checkkey.sh first.

For those who do not yet have an OpenPGP key, or need a new key to meet FreeBSD security requirements, here we show how to generate one.

  1. Install security/gnupg. Enter these lines in ~/.gnupg/gpg.conf to set minimum acceptable defaults:

    fixed-list-mode
    keyid-format 0xlong
    personal-digest-preferences SHA512 SHA384 SHA256 SHA224
    default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 BZIP2 ZLIB ZIP Uncompressed
    use-agent
    verify-options show-uid-validity
    list-options show-uid-validity
    sig-notation issuer-fpr@notations.openpgp.fifthhorseman.net=%g
    cert-digest-algo SHA512
  2. Generate a key:

    % gpg --gen-key
    gpg (GnuPG) 2.0.22; Copyright (C) 2013 Free Software Foundation, Inc.
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.
    
    Warning: using insecure memory!
    Please select what kind of key you want:
       (1) RSA and RSA (default)
       (2) DSA and Elgamal
       (3) DSA (sign only)
       (4) RSA (sign only)
    Your selection? 1
    RSA keys may be between 1024 and 4096 bits long.
    What keysize do you want? (2048) 2048  1
    Requested keysize is 2048 bits
    Please specify how long the key should be valid.
             0 = key does not expire
          <n>  = key expires in n days
          <n>w = key expires in n weeks
          <n>m = key expires in n months
          <n>y = key expires in n years
    Key is valid for? (0) 3y  2
    Key expires at Wed Nov  4 17:20:20 2015 MST
    Is this correct? (y/N) y
    
    GnuPG needs to construct a user ID to identify your key.
    
    Real name: Chucky Daemon 3
    Email address: notreal@example.com
    Comment:
    You selected this USER-ID:
        "Chucky Daemon <notreal@example.com>"
    
    Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
    You need a Passphrase to protect your secret key.

    1

    2048-bit keys with a three-year expiration provide adequate protection at present (2013-12). http://danielpocock.com/rsa-key-sizes-2048-or-4096-bits describes the situation in more detail.

    2

    A three year key lifespan is short enough to obsolete keys weakened by advancing computer power, but long enough to reduce key management problems.

    3

    Use your real name here, preferably matching that shown on government-issued ID to make it easier for others to verify your identity. Text that may help others identify you can be entered in the Comment section.

    After the email address is entered, a passphrase is requested. Methods of creating a secure passphrase are contentious. Rather than suggest a single way, here are some links to sites that describe various methods: http://world.std.com/~reinhold/diceware.html, http://www.iusmentis.com/security/passphrasefaq/, http://xkcd.com/936/, http://en.wikipedia.org/wiki/Passphrase.

Protect your private key and passphrase. If either the private key or passphrase may have been compromised or disclosed, immediately notify and revoke the key.

Committing the new key is shown in Procedure 1, “Steps for New Committers”.

All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/

Questions that are not answered by the documentation may be sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.