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=============================
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Reasons to Sign Your Repository
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--------------------------------
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Bazaar can sign revisions using GnuPG, a Free Software implementation of the
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OpenPGP digital signature format. By signing commits a person wanting to
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make use of a branch can be confident where the code came from, assuming the
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GnuPG keys used can be verified. This could for example prevent worry about
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compromised code in the case where a server hosting Bazaar branches has been
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hacked into. It could also be used to verify that all code is written by a
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select group of people, such as if contributor agreements are needed.
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Signatures are passed around with commits during branch, push, merge and other
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There are many guides to creating a digital signature key with GnuPG. See
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for example the `GnuPG Handbook
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<http://www.gnupg.org/gph/en/manual.html#AEN26>`_ or the `Launchpad Wiki
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<https://help.launchpad.net/YourAccount/ImportingYourPGPKey>`_.
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To sign commits as they are made turn on the ``create_signatures``
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configuration option in your ``bazaar.conf`` or ``locations.conf`` file::
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create_signatures = always
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When you next make a commit it will ask for the pass phrase for your GnuPG key.
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If you want GnuPG to remember your password ensure you have ``gnupg-agent``
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To sign previous commits to a branch use ``sign-my-commits``. This will go
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through all revisions in the branch and sign any which match your
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commit name. You can also pass the name of a contributor to ``sign-my-commits``
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to sign someone else's commits or if your GnuPG key does not match your Bazaar
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bzr sign-my-commits . "Amy Pond <amy@example.com>"
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It will not sign commits which already have a signature.
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To sign a single commit or a range of commits use the (hidden) command
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``re-sign`` is also useful to change an existing signature.
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Unfortunately there is currently no command for verifying signatures. This can
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be done manually using bzrlib and Python::
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>>> from bzrlib.branch import Branch
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>>> b = Branch.open('/home/amy/src/daleks')
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'amy@example.com-20110527185938-hluafawphszb8dl1'
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>>> print b.repository.get_signature_text(b.last_revision())
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-----BEGIN PGP SIGNED MESSAGE-----
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bazaar-ng testament short form 1
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revision-id: amy@example.com-20110527185938-hluafawphszb8dl1
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sha1: 6411f9bdf6571200357140c9ce7c0f50106ac9a4
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-----BEGIN PGP SIGNATURE-----
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Version: GnuPG v1.4.11 (GNU/Linux)
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iEYEARECAAYFAk32HFcACgkQpQbm1N1NUIiBXACg6ILsyvJp4+Twq190qk1I4v9K
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PAAAoI8pg9s7uuqldqOwz6/uwH3ezdSX
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-----END PGP SIGNATURE-----
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The signature can be saved to a file and verified with ``gpg --verify
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The signed SHA1 checksum is made from the ``bzr testament --long`` command
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which includes information on the committer and a list of all files in that
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commit along with their checksums. So if the signature is valid you can be
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sure you are looking at the same code as the person who made the signature.
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There is still a number of digital signature related features which are hoped
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to be added to Bazaar soon. These include easy verificiation, qbzr
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integration, signing with different keys and setting branches to require