git annex rekey [file key ...]
This plumbing-level command is similar to migrate, but you specify both the file, and the new key to use for it.
Multiple pairs of file and key can be given in a single command line.
Allow rekeying of even files whose content is not currently available. Use with caution.
Enables batch mode, in which lines are read from stdin. Each line should contain the file, and the new key to use for that file, separated by a single space.
Makes the --batch input be delimited by nulls instead of the usual newlines.
Joey Hess <firstname.lastname@example.org>