Sign your rpm

GnuPG stands for GNU Privacy Guard and is GNU's tool for secure communication and data storage. It can be used to encrypt data and to create digital signatures. It includes an advanced key management facility and is compliant with the proposed OpenPGP Internet standard as described in RFC 2440. As such, it is aimed to be compatible with PGP from NAI, Inc.

After building your custom RPM package, it's a good idea to sign the package with your own GPG Key to make sure the package is authentic.

In this HOWTO, I'll cover how to generate your own gpg key pair and sign your custom RPM package with that key.

  • Create the gnupg folder
  [root@sme8rpm ]# cd ~
  [root@sme8rpm ]# mkdir .gnupg
  • Generate gpg key pair (public key and private key)
  [root@sme8rpm ]# gpg --gen-key
  gpg (GnuPG) 1.4.5; Copyright (C) 2006 Free Software Foundation, Inc.
  This program comes with ABSOLUTELY NO WARRANTY.
  This is free software, and you are welcome to redistribute it
  under certain conditions. See the file COPYING for details.
  
  gpg: keyring `/root/.gnupg/secring.gpg' created
  gpg: keyring `/root/.gnupg/pubring.gpg' created
  Please select what kind of key you want:
   (1) DSA and ElGamal (default)
   (2) DSA (sign only)
   (4) RSA (sign only)
  '''Your selection? 1'''
  DSA keypair will have 1024 bits.
  About to generate a new ELG-E keypair.
              minimum keysize is  768 bits
              default keysize is 1024 bits
    highest suggested keysize is 2048 bits
  '''What keysize do you want? (1024) 1024'''
  Requested keysize is 1024 bits
  Please specify how long the key should be valid.
         0 = key does not expire
        = key expires in n days
      w = key expires in n weeks
      m = key expires in n months
      y = key expires in n years
  '''Key is valid for? (0) 0'''
  Key does not expire at all
  '''Is this correct (y/n)? y'''
                         
  You need a User-ID to identify your key; the software constructs the user id
  from Real Name, Comment and Email Address in this form:
    "Heinrich Heine (Der Dichter) <heinrichh@duesseldorf.de>"
  
  '''Real name: Foo'''
  '''Email address: foo@foo.com'''
  Comment:
  You selected this USER-ID:
    "Foo <foo@foo.com>"
  
  '''Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O'''
  You need a Passphrase to protect your secret key.
  
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  +++++++++++++.++++++++++++++++++++++++++++++++++++++++++++++++++..+++++
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  ++++++++++++++++..++++++++++++++++++++.+++++++++++++++>+++++...+++++^^^
  gpg: /root/.gnupg/trustdb.gpg: trustdb created
  public and secret key created and signed.
  key marked as ultimately trusted.
  
  pub  1024D/23A254D4 2005-01-06 Foo <foo@foo.com>
     Key fingerprint = 9D71 B237 3AE2 B54A B62D  5DC7 2758 9842 23A2 54D4
  sub  1024g/D08816E2 2005-01-06

* Now that you've generated gpg keys, you can see the list in your key ring by typing :

  [root@sme8rpm]# gpg --list-keys

  /root/.gnupg/pubring.gpg
  -------------------------------
  pub  1024D/23A254D4 2005-01-06 Foo <foo@foo.com>
  sub  1024g/D08816E2 2005-01-06
  • To extract or export your public key from your key ring to a text file.
  [root@sme8rpm]# gpg --export -a 'Foo' > RPM-GPG-KEY

This file is necessary to import it to your RPM DB and verify a package with gpg key later on. If you're planning to share your custom built RPM packages with others, make sure to have your public key file available online in public (in the web folder of your repository) so they can verify your custom RPM package. see Create your repository for an example on how declare the pgp signature to the repository.

  • To import your public key to your RPM DB
  [root@sme8rpm]# rpm --import RPM-GPG-KEY 
  Password:
  • Let's verify the list of gpg public keys in RPM DB:
  [root@sme8rpm]# rpm -q gpg-pubkey --qf '%{name}-%{version}-%{release} --> %{summary}\n'

* Final step before the signing, configure your ~/.rpmmacros file to include the following:

 root@sme8rpm]# nano ~/.rpmmacros

  %_signature gpg
  %_gpg_path /home/youruser/.gnupg
  %_gpg_name Foo
  %_gpgbin /usr/bin/gpg 
  #%__gpg /usr/bin/gpg

* Now, you're ready to sign your custom RPM package (with el7 you must now install rpm-sign)

  root@sme8rpm]# rpmbuild -ba --sign smeserver-roundcube.spec

or

  root@sme8rpm]# rpm --addsign smeserver-roundcube-0.9-15.rpm

or

  root@sme8rpm]# rpm --resign smeserver-roundcube-0.9-15.rpm

to verify if all is ok

  root@sme8rpm]# rpm --checksig smeserver-roundcube-0.9-15.rpm
  smeserver-roundcube-0.9-15.src.rpm: (sha1) dsa sha1 md5 gpg OK

Sign with mock

Mock can sign your rpm for you. To enable this, add the following to ~/.mock/user.cfg:

config_opts['plugin_conf']['sign_enable'] = True
config_opts['plugin_conf']['sign_opts'] = {}
config_opts['plugin_conf']['sign_opts']['cmd'] = 'rpm'
config_opts['plugin_conf']['sign_opts']['opts'] = '--addsign %(rpms)s'

The variable %(rpms)s will be expanded to package file name. This command will run as unprivileged and will get all your environment variables and especially it will run in your $HOME. So ~/.rpmmacros will be interpreted.

Since mock-1.2.14 there is also available variable %(resultdir), which will be expanded to name of directory where are final rpm packages.

https://github.com/rpm-software-management/mock/wiki/Plugin-Sign