Introduce the new CardBackend trait.

A CardBackend represents a card without an open transaction (a CardTransaction implementation can be acquired from a CardBackend).

card-functionality/src/list-cards.rs

@@ -3,6 +3,7 @@
 
 use anyhow::Result;
 
+use openpgp_card::CardBackend;
 use openpgp_card_pcsc::PcscCard;
 use openpgp_card_sequoia::card::Open;
 
@@ -10,9 +11,9 @@ fn main() -> Result<()> {
     println!("The following OpenPGP cards are connected to your system:");
 
     for mut card in PcscCard::cards(None)? {
-        let mut txc = card.transaction()?;
+        let mut txc = <dyn CardBackend>::transaction(&mut card)?;
 
-        let open = Open::new(&mut txc)?;
+        let open = Open::new(&mut *txc)?;
         println!(" {}", open.application_identifier()?.ident());
     }
 

card-functionality/src/tests.rs

@@ -15,7 +15,9 @@ use sequoia_openpgp::Cert;
 use openpgp_card;
 use openpgp_card::algorithm::AlgoSimple;
 use openpgp_card::card_do::{KeyGenerationTime, Sex};
-use openpgp_card::{CardTransaction, Error, KeyType, StatusBytes};
+use openpgp_card::{
+    CardBackend, CardTransaction, Error, KeyType, StatusBytes,
+};
 use openpgp_card_sequoia::card::Open;
 use openpgp_card_sequoia::util::{
     make_cert, public_key_material_to_key, public_to_fingerprint,
@@ -678,7 +680,8 @@ pub fn run_test(
     param: &[&str],
 ) -> Result<TestOutput, TestError> {
     let mut card = tc.get_card()?;
-    let mut txc = card.transaction().map_err(|e| anyhow!(e))?;
+    let mut txc =
+        <dyn CardBackend>::transaction(&mut *card).map_err(|e| anyhow!(e))?;
 
-    t(&mut txc, param)
+    t(&mut *txc, param)
 }

openpgp-card-examples/src/bin/decrypt.rs

@@ -1,8 +1,8 @@
 // SPDX-FileCopyrightText: 2021 Wiktor Kwapisiewicz <wiktor@metacode.biz>
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+use openpgp_card::CardBackend;
 use openpgp_card_pcsc::PcscCard;
-
 use openpgp_card_sequoia::card::Open;
 
 use openpgp::parse::{stream::DecryptorBuilder, Parse};
@@ -23,9 +23,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let cert_file = &args[2];
 
     let mut card = PcscCard::open_by_ident(card_ident, None)?;
-    let mut txc = card.transaction()?;
+    let mut txc = <dyn CardBackend>::transaction(&mut card)?;
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     let pin = std::fs::read_to_string(pin_file)?;
 

openpgp-card-examples/src/bin/detach-sign.rs

@@ -1,8 +1,8 @@
 // SPDX-FileCopyrightText: 2021 Wiktor Kwapisiewicz <wiktor@metacode.biz>
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+use openpgp_card::CardBackend;
 use openpgp_card_pcsc::PcscCard;
-
 use openpgp_card_sequoia::card::Open;
 
 use openpgp::parse::Parse;
@@ -23,9 +23,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let cert_file = &args[2];
 
     let mut card = PcscCard::open_by_ident(card_ident, None)?;
-    let mut txc = card.transaction()?;
+    let mut txc = <dyn CardBackend>::transaction(&mut card)?;
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     let pin = std::fs::read_to_string(pin_file)?;
 

openpgp-card-sequoia/src/lib.rs

@@ -16,9 +16,10 @@
 //! use openpgp_card_pcsc::PcscCard;
 //!
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! # use openpgp_card::CardBackend;
 //! for mut card in PcscCard::cards(None)? {
-//!     let mut txc = card.transaction()?;
+//!     let mut txc = <dyn CardBackend>::transaction(&mut card)?;
-//!     let open = Open::new(&mut txc)?;
+//!     let open = Open::new(&mut *txc)?;
 //!     println!("Found OpenPGP card with ident '{}'",
 //!              open.application_identifier()?.ident());
 //! }
@@ -33,9 +34,10 @@
 //! use openpgp_card_pcsc::PcscCard;
 //!
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! # use openpgp_card::CardBackend;
 //! let mut card = PcscCard::open_by_ident("abcd:12345678", None)?;
-//! let mut txc = card.transaction()?;
+//! let mut txc = <dyn CardBackend>::transaction(&mut card)?;
-//! let mut open = Open::new(&mut txc)?;
+//! let mut open = Open::new(&mut *txc)?;
 //! # Ok(())
 //! # }
 //! ```
@@ -56,9 +58,10 @@
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
 //! // Open card via PCSC
 //! use sequoia_openpgp::policy::StandardPolicy;
+//! # use openpgp_card::CardBackend;
 //! let mut card = PcscCard::open_by_ident("abcd:12345678", None)?;
-//! let mut txc = card.transaction()?;
+//! let mut txc = <dyn CardBackend>::transaction(&mut card)?;
-//! let mut open = Open::new(&mut txc)?;
+//! let mut open = Open::new(&mut *txc)?;
 //!
 //! // Get authorization for user access to the card with password
 //! open.verify_user("123456")?;
@@ -96,11 +99,12 @@
 //! use openpgp_card_pcsc::PcscCard;
 //!
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! # use openpgp_card::CardBackend;
 //! // Open card via PCSC
 //! use sequoia_openpgp::policy::StandardPolicy;
 //! let mut card = PcscCard::open_by_ident("abcd:12345678", None)?;
-//! let mut txc = card.transaction()?;
+//! let mut txc = <dyn CardBackend>::transaction(&mut card)?;
-//! let mut open = Open::new(&mut txc)?;
+//! let mut open = Open::new(&mut *txc)?;
 //!
 //! // Get authorization for signing access to the card with password
 //! open.verify_user_for_signing("123456")?;
@@ -128,10 +132,11 @@
 //! use openpgp_card_pcsc::PcscCard;
 //!
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! # use openpgp_card::CardBackend;
 //! // Open card via PCSC
 //! let mut card = PcscCard::open_by_ident("abcd:12345678", None)?;
-//! let mut txc = card.transaction()?;
+//! let mut txc = <dyn CardBackend>::transaction(&mut card)?;
-//! let mut open = Open::new(&mut txc)?;
+//! let mut open = Open::new(&mut *txc)?;
 //!
 //! // Get authorization for admin access to the card with password
 //! open.verify_admin("12345678")?;

openpgp-card-sequoia/src/main.rs

@@ -10,6 +10,7 @@ use sequoia_openpgp::policy::StandardPolicy;
 use sequoia_openpgp::Cert;
 
 use openpgp_card::card_do::Sex;
+use openpgp_card::CardBackend;
 use openpgp_card::KeyType;
 use openpgp_card_pcsc::PcscCard;
 
@@ -38,7 +39,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         let mut card = PcscCard::open_by_ident(&test_card_ident, None)?;
         let mut txc = card.transaction()?;
 
-        let mut open = Open::new(&mut txc)?;
+        let mut open = Open::new(&mut *txc)?;
 
         // card metadata
 
@@ -149,7 +150,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         let mut card = PcscCard::open_by_ident(&test_card_ident, None)?;
         let mut txc = card.transaction()?;
 
-        let mut open = Open::new(&mut txc)?;
+        let mut open = Open::new(&mut *txc)?;
 
         // Check that we're still using the expected card
         let app_id = open.application_identifier()?;
@@ -190,7 +191,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         let mut card = PcscCard::open_by_ident(&test_card_ident, None)?;
         let mut txc = card.transaction()?;
 
-        let mut open = Open::new(&mut txc)?;
+        let mut open = Open::new(&mut *txc)?;
 
         // Sign
         open.verify_user_for_signing("123456")?;
@@ -222,7 +223,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         for mut card in PcscCard::cards(None)? {
             let mut txc = card.transaction()?;
 
-            let open = Open::new(&mut txc)?;
+            let open = Open::new(&mut *txc)?;
             println!(" {}", open.application_identifier()?.ident());
         }
     }

openpgp-card/src/lib.rs

@@ -55,6 +55,12 @@ use crate::tlv::tag::Tag;
 use crate::tlv::value::Value;
 use crate::tlv::Tlv;
 
+pub trait CardBackend {
+    fn transaction(
+        &mut self,
+    ) -> Result<Box<dyn CardTransaction + Send + Sync + '_>, Error>;
+}
+
 /// The CardTransaction trait defines communication with an OpenPGP card via a
 /// backend implementation (e.g. the pcsc backend in the crate
 /// [openpgp-card-pcsc](https://crates.io/crates/openpgp-card-pcsc)),

pcsc/src/lib.rs

@@ -12,7 +12,9 @@ use std::collections::HashMap;
 use std::convert::TryInto;
 
 use openpgp_card::card_do::ApplicationRelatedData;
-use openpgp_card::{CardCaps, CardTransaction, Error, SmartcardError};
+use openpgp_card::{
+    CardBackend, CardCaps, CardTransaction, Error, SmartcardError,
+};
 
 const FEATURE_VERIFY_PIN_DIRECT: u8 = 0x06;
 const FEATURE_MODIFY_PIN_DIRECT: u8 = 0x07;
@@ -61,7 +63,7 @@ impl<'b> TxClient<'b> {
     /// `reselect` set to `false` is only used internally in this crate,
     /// during initial setup of cards. Otherwise it must be `true`, to
     /// cause a select() call on cards that have been reset.
-    fn new(card: &'b mut PcscCard, reselect: bool) -> Result<Self> {
+    fn new(card: &'b mut PcscCard, reselect: bool) -> Result<Self, Error> {
         use pcsc::Disposition;
 
         let mut was_reset = false;
@@ -452,11 +454,6 @@ impl PcscCard {
         self.mode
     }
 
-    /// Get a TxClient for this PcscCard (this starts a transaction)
-    pub fn transaction(&mut self) -> Result<TxClient> {
-        TxClient::new(self, true)
-    }
-
     /// A list of "raw" opened PCSC Cards (without selecting the OpenPGP card
     /// application)
     fn raw_pcsc_cards(mode: ShareMode) -> Result<Vec<Card>, SmartcardError> {
@@ -647,7 +644,7 @@ impl PcscCard {
 
         let mut h: HashMap<u8, Tlv> = HashMap::default();
 
-        let mut txc = self.transaction()?;
+        let mut txc = TxClient::new(&mut self, true)?;
 
         // Get Features from reader (pinpad verify/modify)
         if let Ok(feat) = txc.features() {
@@ -680,3 +677,12 @@ impl PcscCard {
         self.reader_caps.clone()
     }
 }
+
+impl CardBackend for PcscCard {
+    /// Get a TxClient for this PcscCard (this starts a transaction)
+    fn transaction(
+        &mut self,
+    ) -> Result<Box<dyn CardTransaction + Send + Sync + '_>, Error> {
+        Ok(Box::new(TxClient::new(self, true)?))
+    }
+}

tools/src/bin/opgpcard-pin/main.rs

@@ -4,7 +4,7 @@
 use anyhow::Result;
 use structopt::StructOpt;
 
-use openpgp_card::{CardTransaction, Error, StatusBytes};
+use openpgp_card::{CardBackend, Error, StatusBytes};
 use openpgp_card_pcsc::PcscCard;
 use openpgp_card_sequoia::card::Open;
 
@@ -21,7 +21,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let pinpad_verify = txc.feature_pinpad_verify();
     let pinpad_modify = txc.feature_pinpad_modify();
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     match cli.cmd {
         cli::Command::SetUserPin {} => {

tools/src/bin/opgpcard/main.rs

@@ -12,7 +12,8 @@ use sequoia_openpgp::serialize::SerializeInto;
 use sequoia_openpgp::Cert;
 
 use openpgp_card::algorithm::AlgoSimple;
-use openpgp_card::{card_do::Sex, CardTransaction, KeyType};
+use openpgp_card::CardBackend;
+use openpgp_card::{card_do::Sex, KeyType};
 
 use openpgp_card_sequoia::card::{Admin, Open};
 use openpgp_card_sequoia::util::{make_cert, public_key_material_to_key};
@@ -73,7 +74,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             let mut card = util::open_card(&ident)?;
             let mut txc = card.transaction()?;
 
-            let mut open = Open::new(&mut txc)?;
+            let mut open = Open::new(&mut *txc)?;
 
             match cmd {
                 cli::AdminCommand::Name { name } => {
@@ -140,7 +141,7 @@ fn list_cards() -> Result<()> {
         for mut card in cards {
             let mut txc = card.transaction()?;
 
-            let open = Open::new(&mut txc)?;
+            let open = Open::new(&mut *txc)?;
             println!(" {}", open.application_identifier()?.ident());
         }
     } else {
@@ -156,7 +157,7 @@ fn set_identity(
     let mut card = util::open_card(ident)?;
     let mut txc = card.transaction()?;
 
-    <dyn CardTransaction>::set_identity(&mut txc, id)?;
+    txc.set_identity(id)?;
 
     Ok(())
 }
@@ -175,7 +176,7 @@ fn print_status(ident: Option<String>, verbose: bool) -> Result<()> {
 
     let mut txc = card.transaction()?;
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     let ident = open.application_identifier()?.ident();
 
@@ -336,7 +337,7 @@ fn decrypt(
     let mut card = util::open_card(ident)?;
     let mut txc = card.transaction()?;
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     let mut user = util::verify_to_user(&mut open, pin_file)?;
     let d = user.decryptor(&cert)?;
@@ -362,7 +363,7 @@ fn sign_detached(
     let mut card = util::open_card(ident)?;
     let mut txc = card.transaction()?;
 
-    let mut open = Open::new(&mut txc)?;
+    let mut open = Open::new(&mut *txc)?;
 
     let mut sign = util::verify_to_sign(&mut open, pin_file)?;
     let s = sign.signer(&cert)?;
@@ -381,7 +382,7 @@ fn factory_reset(ident: &str) -> Result<()> {
     let mut card = util::open_card(ident)?;
     let mut txc = card.transaction()?;
 
-    Open::new(&mut txc)?.factory_reset()
+    Open::new(&mut *txc)?.factory_reset()
 }
 
 fn key_import_yolo(mut admin: Admin, key: &Cert) -> Result<()> {