Add packet session key identifiers

src/auth.rs

@@ -1,5 +1,6 @@
 use crate::config::{ServerConfig, expand_tilde};
 use crate::crypto;
+use crate::protocol;
 use anyhow::{Context, Result};
 use base64::Engine;
 use base64::engine::general_purpose::URL_SAFE_NO_PAD;
@@ -105,12 +106,7 @@ pub fn build_bootstrap(
         &client_nonce,
         format!("dosh/session/{user}/{session}/{issued_at}").as_bytes(),
     )?;
-    let session_key_id = {
-        let digest = crypto::sha256(&session_key);
-        let mut out = [0u8; 16];
-        out.copy_from_slice(&digest[..16]);
-        out
-    };
+    let session_key_id = protocol::session_key_id(&session_key);
     let attach_token = attach_token(
         secret,
         &user,