Refactor: add a set_fingerprint() method to CardApp.

Use that method instead of manually calling the apdu command.
Change type of fingerprint in CardUploadableKey to [u8; 20].

openpgp-card-sequoia/src/lib.rs

@@ -5,6 +5,7 @@
 //! sequoia_openpgp data structures.
 
 use std::convert::TryFrom;
+use std::convert::TryInto;
 use std::error::Error;
 use std::io;
 use std::time::SystemTime;
@@ -171,8 +172,11 @@ impl CardUploadableKey for SequoiaKey {
         ts.into()
     }
 
-    fn get_fp(&self) -> Vec<u8> {
-        self.key.fingerprint().as_bytes().to_vec()
+    fn get_fp(&self) -> [u8; 20] {
+        let fp = self.key.fingerprint();
+        assert_eq!(fp.as_bytes().len(), 20);
+
+        fp.as_bytes().try_into().unwrap()
     }
 }
 

openpgp-card/src/card_app.rs

@@ -546,6 +546,19 @@ impl CardApp {
         apdu::send_command(&mut self.card_client, time_cmd, false)
     }
 
+    pub fn set_fingerprint(
+        &mut self,
+        fp: [u8; 20],
+        key_type: KeyType,
+    ) -> Result<Response, OpenpgpCardError> {
+        let fp_cmd = commands::put_data(
+            &[key_type.get_fingerprint_put_tag()],
+            fp.to_vec(),
+        );
+
+        apdu::send_command(self.card(), fp_cmd, true)
+    }
+
     /// Set algorithm attributes [4.4.3.9 Algorithm Attributes]
     pub fn set_algorithm_attributes(
         &mut self,

openpgp-card/src/keys.rs

@@ -40,10 +40,7 @@ pub(crate) fn gen_key_with_metadata(
 
     // calculate/store fingerprint
     let fp = fp_from_pub(&pubkey, time)?;
-    let fp_cmd =
-        commands::put_data(&[key_type.get_fingerprint_put_tag()], fp.to_vec());
-
-    apdu::send_command(card_app.card(), fp_cmd, true)?.check_ok()?;
+    card_app.set_fingerprint(fp, key_type)?.check_ok()?;
 
     Ok(())
 }
@@ -442,12 +439,10 @@ fn copy_key_to_card(
     card_app: &mut CardApp,
     key_type: KeyType,
     ts: u32,
-    fp: Vec<u8>,
+    fp: [u8; 20],
     algo: &Algo,
     key_cmd: Command,
 ) -> Result<(), OpenpgpCardError> {
-    let fp_cmd = commands::put_data(&[key_type.get_fingerprint_put_tag()], fp);
-
     // Send all the commands
 
     // FIXME: Only write algo attributes to the card if "extended
@@ -457,7 +452,8 @@ fn copy_key_to_card(
         .check_ok()?;
 
     apdu::send_command(card_app.card(), key_cmd, false)?.check_ok()?;
-    apdu::send_command(card_app.card(), fp_cmd, false)?.check_ok()?;
+
+    card_app.set_fingerprint(fp, key_type)?.check_ok()?;
 
     card_app.set_creation_time(ts, key_type)?.check_ok()?;
 

openpgp-card/src/lib.rs

@@ -124,7 +124,7 @@ pub trait CardUploadableKey {
     fn get_ts(&self) -> u32;
 
     /// fingerprint
-    fn get_fp(&self) -> Vec<u8>;
+    fn get_fp(&self) -> [u8; 20];
 }
 
 /// Algorithm-independent container for public key material retrieved from