security/rvault: import rvault-0.1

rvault is a secure and authenticated store for secrets (passwords,
keys, certificates) and small documents.  It uses envelope encryption
with one-time password (OTP) authentication.  The vault can be operated
as a file system in userspace.  It is written in C11 and distributed
under the 2-clause BSD license.

From rmind@

(wiz)