Any protection against 'bit rot' ?

[Andy <tarsnap-users@orgdotuk.org.uk>]

Hello all.

Sorry if this is answered on a FAQ, or has been raised on the list
before.  Tarsnap's moto is "Online backups for the truly paranoid", so
today I've got my paranoid hat on.  I am building a home NAS and am
trying to keep its data as safe as possible from silent corruption aka
'bit rot' - it has ECC RAM, and data will live on ZFS.  I would like
to have the same warm feeling about the data that I send for off-site
backup.  What protection does tarsnap have against this kind of data
loss?

Many thanks    Andy