keyfork-shard: make custom error for Sharks errors

keyfork-shard/src/lib.rs

@@ -15,6 +15,15 @@ use x25519_dalek::{EphemeralSecret, PublicKey};
 #[cfg(feature = "openpgp")]
 pub mod openpgp;
 
+#[derive(thiserror::Error, Debug)]
+pub enum SharksError {
+    #[error("Error creating share: {0}")]
+    Share(String),
+
+    #[error("Error combining shares: {0}")]
+    CombineShare(String),
+}
+
 /// Decrypt hunk version 1:
 /// 1 byte: Version
 /// 1 byte: Threshold
@@ -94,10 +103,10 @@ pub fn remote_decrypt() -> Result<(), Box<dyn std::error::Error>> {
         .into_iter()
         .map(|s| Share::try_from(s.as_slice()))
         .collect::<Result<Vec<_>, &str>>()
-        .map_err(|e| anyhow::anyhow!("{e}"))?;
+        .map_err(|e| SharksError::Share(e.to_string()))?;
     let secret = Sharks(threshold)
         .recover(&shares)
-        .map_err(|e| anyhow::anyhow!("{e}"))?;
+        .map_err(|e| SharksError::CombineShare(e.to_string()))?;
 
     /*
      * Verification would take up too much size, mnemonic would be very large

keyfork-shard/src/openpgp.rs

@@ -48,22 +48,19 @@ use smartcard::SmartcardManager;
 const SHARD_METADATA_VERSION: u8 = 1;
 const SHARD_METADATA_OFFSET: usize = 2;
 
-use super::HUNK_VERSION;
+use super::{HUNK_VERSION, SharksError};
 
 // 256 bit share is 49 bytes + some amount of hunk bytes, gives us reasonable padding
 const ENC_LEN: u8 = 4 * 16;
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
-    #[error("Error with creating Share: {0}")]
-    Share(String),
+    #[error("{0}")]
+    Sharks(#[from] SharksError),
 
     #[error("Error decrypting share: {0}")]
     SymDecryptShare(#[from] AesError),
 
-    #[error("Error combining shares: {0}")]
-    CombineShares(String),
-
     #[error("Derived secret hash {0} != expected {1}")]
     InvalidSecret(Fingerprint, Fingerprint),
 
@@ -509,10 +506,10 @@ pub fn combine(
         .values()
         .map(|message| Share::try_from(message.as_slice()))
         .collect::<Result<Vec<_>, &str>>()
-        .map_err(|e| Error::Share(e.to_string()))?;
+        .map_err(|e| SharksError::Share(e.to_string()))?;
     let secret = Sharks(threshold)
         .recover(&shares)
-        .map_err(|e| Error::CombineShares(e.to_string()))?;
+        .map_err(|e| SharksError::CombineShare(e.to_string()))?;
 
     // TODO: extract as function
     let userid = UserID::from("keyfork-sss");