Use the openpgp_card::card_do::Fingerprint type instead of [u8; 20].

Add a TryFrom<&[u8]> implementation to Fingerprint.

openpgp-card-sequoia/src/lib.rs

@@ -364,11 +364,9 @@ impl CardUploadableKey for SequoiaKey {
         ts.into()
     }
 
-    fn get_fp(&self) -> [u8; 20] {
+    fn get_fp(&self) -> Result<Fingerprint, OpenpgpCardError> {
         let fp = self.key.fingerprint();
-        assert_eq!(fp.as_bytes().len(), 20);
+        fp.as_bytes().try_into()
-
-        fp.as_bytes().try_into().unwrap()
     }
 }
 
@@ -539,16 +537,13 @@ pub fn public_to_fingerprint(
     pkm: &PublicKeyMaterial,
     ts: SystemTime,
     kt: KeyType,
-) -> Result<[u8; 20]> {
+) -> Result<Fingerprint, OpenpgpCardError> {
     // Transform PublicKeyMaterial into a Sequoia Key
     let key = public_key_material_to_key(pkm, kt, ts)?;
 
     // Get fingerprint from the Sequoia Key
     let fp = key.fingerprint();
-    let fp = fp.as_bytes();
+    fp.as_bytes().try_into()
-
-    assert_eq!(fp.len(), 20);
-    Ok(fp.try_into()?)
 }
 
 // --------

openpgp-card/src/card_app.rs

@@ -11,7 +11,8 @@ use anyhow::{anyhow, Result};
 use crate::algorithm::{Algo, AlgoInfo, AlgoSimple, RsaAttrs};
 use crate::apdu::{commands, response::Response};
 use crate::card_do::{
-    ApplicationRelatedData, Cardholder, PWStatus, SecuritySupportTemplate, Sex,
+    ApplicationRelatedData, Cardholder, Fingerprint, PWStatus,
+    SecuritySupportTemplate, Sex,
 };
 use crate::crypto_data::{
     CardUploadableKey, Cryptogram, EccType, Hash, PublicKeyMaterial,
@@ -487,12 +488,12 @@ impl CardApp {
 
     pub fn set_fingerprint(
         &mut self,
-        fp: [u8; 20],
+        fp: Fingerprint,
         key_type: KeyType,
     ) -> Result<Response, OpenpgpCardError> {
         let fp_cmd = commands::put_data(
             &[key_type.get_fingerprint_put_tag()],
-            fp.to_vec(),
+            fp.as_bytes().to_vec(),
         );
 
         apdu::send_command(self.card(), fp_cmd, false)?.try_into()
@@ -620,7 +621,7 @@ impl CardApp {
             &PublicKeyMaterial,
             SystemTime,
             KeyType,
-        ) -> Result<[u8; 20]>,
+        ) -> Result<Fingerprint, OpenpgpCardError>,
         key_type: KeyType,
         algo: Option<&Algo>,
     ) -> Result<(PublicKeyMaterial, u32), OpenpgpCardError> {
@@ -635,7 +636,7 @@ impl CardApp {
             &PublicKeyMaterial,
             SystemTime,
             KeyType,
-        ) -> Result<[u8; 20]>,
+        ) -> Result<Fingerprint, OpenpgpCardError>,
         key_type: KeyType,
         algo: AlgoSimple,
     ) -> Result<(PublicKeyMaterial, u32), OpenpgpCardError> {

openpgp-card/src/card_do/fingerprint.rs

@@ -3,6 +3,8 @@
 
 use anyhow::anyhow;
 use nom::{bytes::complete as bytes, combinator, sequence};
+use std::convert::TryFrom;
+use std::convert::TryInto;
 use std::fmt;
 
 use crate::card_do::{Fingerprint, KeySet};
@@ -14,6 +16,24 @@ impl From<[u8; 20]> for Fingerprint {
     }
 }
 
+impl TryFrom<&[u8]> for Fingerprint {
+    type Error = OpenpgpCardError;
+
+    fn try_from(input: &[u8]) -> Result<Self, Self::Error> {
+        log::trace!(
+            "Fingerprint from input: {:x?}, len {}",
+            input,
+            input.len()
+        );
+
+        // FIXME: return error
+        assert_eq!(input.len(), 20);
+
+        let array: [u8; 20] = input.try_into().unwrap();
+        Ok(array.into())
+    }
+}
+
 impl Fingerprint {
     pub fn as_bytes(&self) -> &[u8] {
         &self.0

openpgp-card/src/crypto_data.rs

@@ -8,6 +8,8 @@
 use anyhow::Result;
 
 use crate::algorithm::Algo;
+use crate::card_do::Fingerprint;
+use crate::errors::OpenpgpCardError;
 
 /// A hash value that can be signed by the card.
 pub enum Hash<'a> {
@@ -67,7 +69,7 @@ pub trait CardUploadableKey {
     fn get_ts(&self) -> u32;
 
     /// fingerprint
-    fn get_fp(&self) -> [u8; 20];
+    fn get_fp(&self) -> Result<Fingerprint, OpenpgpCardError>;
 }
 
 /// Algorithm-independent container for private key material to upload to

openpgp-card/src/keys.rs

@@ -11,6 +11,7 @@ use crate::algorithm::{Algo, AlgoInfo, Curve, EccAttrs, RsaAttrs};
 use crate::apdu::command::Command;
 use crate::apdu::commands;
 use crate::card_app::CardApp;
+use crate::card_do::Fingerprint;
 use crate::crypto_data::{
     CardUploadableKey, EccKey, EccPub, PrivateKeyMaterial, PublicKeyMaterial,
     RSAKey, RSAPub,
@@ -27,7 +28,7 @@ pub(crate) fn gen_key_with_metadata(
         &PublicKeyMaterial,
         SystemTime,
         KeyType,
-    ) -> Result<[u8; 20]>,
+    ) -> Result<Fingerprint, OpenpgpCardError>,
     key_type: KeyType,
     algo: Option<&Algo>,
 ) -> Result<(PublicKeyMaterial, u32), OpenpgpCardError> {
@@ -210,7 +211,7 @@ pub(crate) fn upload_key(
         card_app,
         key_type,
         key.get_ts(),
-        key.get_fp(),
+        key.get_fp()?,
         &algo,
         key_cmd,
     )?;
@@ -427,7 +428,7 @@ fn copy_key_to_card(
     card_app: &mut CardApp,
     key_type: KeyType,
     ts: u32,
-    fp: [u8; 20],
+    fp: Fingerprint,
     algo: &Algo,
     key_cmd: Command,
 ) -> Result<(), OpenpgpCardError> {