enhance(cli): add context to public/secret key decoding errors

.changes/cli-updater-errorr.md

@@ -0,0 +1,7 @@
+---
+"tauri-cli": "patch:enhance"
+"@tauri-apps/cli": "patch:enhance"
+---
+
+Add more context for errors when decoding secret and public keys for signing updater artifacts.
+

crates/tauri-cli/src/bundle.rs

@@ -9,7 +9,6 @@ use std::{
 };
 
 use anyhow::Context;
-use base64::Engine;
 use clap::{builder::PossibleValue, ArgAction, Parser, ValueEnum};
 use tauri_bundler::PackageType;
 use tauri_utils::platform::Target;
@@ -257,15 +256,14 @@ fn sign_updaters(
   // check if private_key points to a file...
   let maybe_path = Path::new(&private_key);
   let private_key = if maybe_path.exists() {
-    std::fs::read_to_string(maybe_path)?
+    std::fs::read_to_string(maybe_path)
+      .with_context(|| format!("faild to read {}", maybe_path.display()))?
   } else {
     private_key
   };
-  let secret_key = updater_signature::secret_key(private_key, password)?;
-
-  let pubkey = base64::engine::general_purpose::STANDARD.decode(pubkey)?;
-  let pub_key_decoded = String::from_utf8_lossy(&pubkey);
-  let public_key = minisign::PublicKeyBox::from_string(&pub_key_decoded)?.into_public_key()?;
+  let secret_key =
+    updater_signature::secret_key(private_key, password).context("failed to decode secret key")?;
+  let public_key = updater_signature::pub_key(pubkey).context("failed to decode pubkey")?;
 
   let mut signed_paths = Vec::new();
   for bundle in update_enabled_bundles {

crates/tauri-cli/src/helpers/updater_signature.rs

@@ -4,7 +4,9 @@
 
 use anyhow::Context;
 use base64::Engine;
-use minisign::{sign, KeyPair as KP, SecretKey, SecretKeyBox, SignatureBox};
+use minisign::{
+  sign, KeyPair as KP, PublicKey, PublicKeyBox, SecretKey, SecretKeyBox, SignatureBox,
+};
 use std::{
   fs::{self, File, OpenOptions},
   io::{BufReader, BufWriter, Write},
@@ -132,15 +134,24 @@ pub fn secret_key<S: AsRef<[u8]>>(
   private_key: S,
   password: Option<String>,
 ) -> crate::Result<SecretKey> {
-  let decoded_secret = decode_key(private_key)?;
-  let sk_box = SecretKeyBox::from_string(&decoded_secret)
-    .with_context(|| "failed to load updater private key")?;
+  let decoded_secret = decode_key(private_key).context("failed to decode base64 secret key")?;
+  let sk_box =
+    SecretKeyBox::from_string(&decoded_secret).context("failed to load updater private key")?;
   let sk = sk_box
     .into_secret_key(password)
-    .with_context(|| "incorrect updater private key password")?;
+    .context("incorrect updater private key password")?;
   Ok(sk)
 }
 
+/// Gets the updater secret key from the given private key and password.
+pub fn pub_key<S: AsRef<[u8]>>(public_key: S) -> crate::Result<PublicKey> {
+  let decoded_publick = decode_key(public_key).context("failed to decode base64 pubkey")?;
+  let pk_box =
+    PublicKeyBox::from_string(&decoded_publick).context("failed to load updater pubkey")?;
+  let pk = pk_box.into_public_key()?;
+  Ok(pk)
+}
+
 fn unix_timestamp() -> u64 {
   let start = SystemTime::now();
   let since_the_epoch = start