Utility to compute, or verify (default), the signed hash of a Portage repo tree
porthash is a simple script that creates, or by default verifies, a signed sha512 "master" hash of the specified Portage repostitory tree (by default, /var/db/repos/gentoo). It is intended to provide assurance - when distributing a repo snapshot over an unauthenticated channel such as rsync - that the consitutent ebuilds, manifests etc. have not been tampered with in transit.
The cascaded ("master") hash covers the contents of all files in the repository tree (excluding distfiles/..., packages/..., local/, .git/..., and, optionally, ./metadata/...) together with some metadata about these files and their containing directories (name, perms, type, owner, and group).
Please see the included manpage for further details.
porthash is best installed (on Gentoo) via its ebuild, available as part of the sakaki-tools overlay.