debsig-verify - Verify signatures for a Debian format package
debsig-verify [options] <deb>
This program is part of a security model that verifies the source and
validity of a Debian format package (commonly refered to as a deb).
This program implements the verification specs defined in the document,
"Package Verification with dpkg: Implementation", which is a more
complete reference for the verification procedure.
The program generally takes one argument, the deb file to be verified.
It will then check the origin signature of the deb, find its Public Key
ID (long format), and use that as the name for a policy subdirectory.
If this subdirectory does not exist, then the verification fails
In this subdirectory, the program finds one or more files named with
the .pol file extension, which signifies an XML format policy
definition. This file contains three main parts.
Origin Information about the origin of this policy.
Rules used to decide if this policy is pertinent to this deb’s
Rules that are used to actually verify the deb.
The policy files will reference keyrings by a filename. These keyrings
will be looked for in a subdirectory of the keyring directory. The
subdirectory has the same name as the policy subdirectory (previously
determined by the Origin’s Public Key ID).
The program will, after first parsing the entire file, check the Origin
ID against the Public Key ID of the origin signature in the deb. If
these match (which they should, else something is really wrong), then
it will proceed to the Selection rules.
The Selection rules decide whether this policy is suitable for
verifying this deb. If these rules fail, then the program will proceed
to the next policy. If it passes, then the program commits to using
this policy for verification, and no other policies will be referenced.
The last verification step relies on the Verification rules. These are
similar in format to the Selection rules, but are usually more
constrained. If these rules fail, the program exits with a non-zero
status. If they pass, then it exits with a zero status.
-q Causes the program to send no output, other than fatal errors.
This is useful when being called from another program, where you
rely on the exit value only.
-v Causes the program to send more output on execution, so as to
follow the steps it is taking while trying to verify the deb.
-d Outputs even more info than the -v option. This is mainly for
Outputs the version information for the program. This includes
the policy format version. This option does not require any
Outputs a list of the policies that passed the Selection phase
of the verification process. In other words, those that could
potentially verify the deb. The output is one line showing the
directory selected by the origin signature, and then a single
line for any policy files in that directory that pass the
Selection rules. This option will NOT verify the deb.
This option takes one argument, which is the name of the policy
file (as shown by the --list-policies option). Note, this is
just a file, and not a full path. You cannot specifiy arbitrary
policies. This option is useful if more than one policy applies
to potentially verifying the deb. The program will then use this
policy, and only this policy, to try and verify the deb.
Directory containing the policy (.pol) definitions.
XML format policy files.
Directory containing the keyrings that coincide with the
GPG format keyrings for use by the policies.
Ben Collins <email@example.com>