keymgr: Remove unused helper.

This helper is no longer needed (the logic from
`parse_ssh_format_erased` changed).

crates/tor-keymgr/src/key_type/ssh.rs

@@ -122,39 +122,6 @@ impl HasKind for SshKeyError {
     }
 }
 
-/// A helper for reading Ed25519 OpenSSH private keys from disk.
-fn read_ed25519_keypair(key_type: KeyType, key: UnparsedOpenSshKey) -> Result<ed25519::Keypair> {
-    let sk =
-        ssh_key::PrivateKey::from_openssh(&*key.inner).map_err(|e| SshKeyError::SshKeyParse {
-            // TODO: rust thinks this clone is necessary because key.path is also used below (but
-            // if we get to this point, we're going to return an error and never reach the other
-            // error handling branches where we use key.path).
-            path: key.path.clone(),
-            key_type,
-            err: e.into(),
-        })?;
-
-    // Build the expected key type (i.e. convert ssh_key key types to the key types
-    // we're using internally).
-    let key = match sk.key_data() {
-        KeypairData::Ed25519(key) => {
-            ed25519::Keypair::from_bytes(&key.to_bytes()).map_err(|_| {
-                tor_error::internal!("failed to build ed25519 key out of ed25519 OpenSSH key")
-            })?
-        }
-        _ => {
-            return Err(SshKeyError::UnexpectedSshKeyType {
-                path: key.path,
-                wanted_key_algo: key_type.ssh_algorithm(),
-                found_key_algo: sk.algorithm().into(),
-            }
-            .boxed());
-        }
-    };
-
-    Ok(key)
-}
-
 impl KeyType {
     /// Get the algorithm of this key type.
     pub(crate) fn ssh_algorithm(&self) -> SshKeyAlgorithm {