2 unstable releases
0.5.0 | Sep 5, 2023 |
---|---|
0.4.0 | Aug 28, 2023 |
#1333 in Hardware support
Used in openpgp-card-rpgp
23KB
301 lines
scdaemon based backend (e.g., for the openpgp-card library)
This crate provides ScdBackend
/ScdTransaction
, which is an implementation
of the CardBackend
/CardTransaction
traits that uses an instance of GnuPG's
scdaemon
to access OpenPGP cards.
Note that (unlike card-backend-pcsc
), this backend doesn't implement
transaction guarantees.
Known limitations
-
Uploading RSA 4096 keys via
scdaemon
doesn't work with cards that don't support Command Chaining (e.g. the "Floss Shop OpenPGP Smart Card"). This is caused by a size limitation for client requests via the Assuan protocol. Assuan "Client requests" are limited to 1000 chars. Commands are sent as ASCII encoded hex, so APDU commands are limited to around 480 bytes. This is insufficient for importing RSA 4096 keys to the card (all other OpenPGP card operations fit into this constraint). -
When using
scdaemon
via pcsc (by configuringscdaemon
withdisable-ccid
), choosing a specific card of multiple plugged-in OpenPGP cards seems to be broken. So you probably want to plug in only one OpenPGP card at a time when usingopenpgp-card-scdc
combined withdisable-ccid
. -
When using
scdaemon
via its defaultccid
driver, choosing a specific one of multiple plugged-in OpenPGP cards seems to only work up to 4 plugged-in cards. So you probably want to plug in at most four OpenPGP cards at a time when usingcard-backend-scdc
with its ccid driver. (This limit has been raised in GnuPG 2.3.x)
Dependencies
~23–37MB
~469K SLoC