community: the soulseek link proof, one message to yourself links the account and one question links anyone who answers

crates/persona-state/src/lib.rs

@@ -15,6 +15,8 @@
 use ed25519_dalek::{Signature, Verifier, VerifyingKey};
 use serde::{Deserialize, Serialize};
 
+pub mod slsk_link;
+
 pub const SCHEMA_VERSION: u32 = 1;
 pub const SIGN_DOMAIN: &str = "soulstream.profile/v1";
 
@@ -76,7 +78,7 @@ pub fn profile_sign_payload(p: &ProfileState) -> Vec<u8> {
     .expect("serializes")
 }
 
-fn signable(domain: &str, payload: &[u8]) -> Vec<u8> {
+pub(crate) fn signable(domain: &str, payload: &[u8]) -> Vec<u8> {
     let mut msg = Vec::new();
     msg.extend_from_slice(b"soulstream.sig.v1");
     msg.push(0);
@@ -87,9 +89,14 @@ fn signable(domain: &str, payload: &[u8]) -> Vec<u8> {
 }
 
 pub fn verify_sig(public: &[u8; 32], payload: &[u8], sig: &[u8]) -> bool {
+    verify_sig_in(SIGN_DOMAIN, public, payload, sig)
+}
+
+/// The same check under an explicit domain — the link and friend families.
+pub fn verify_sig_in(domain: &str, public: &[u8; 32], payload: &[u8], sig: &[u8]) -> bool {
     let Ok(vk) = VerifyingKey::from_bytes(public) else { return false };
     let Ok(sig) = Signature::from_slice(sig) else { return false };
-    vk.verify(&signable(SIGN_DOMAIN, payload), &sig).is_ok()
+    vk.verify(&signable(domain, payload), &sig).is_ok()
 }
 
 pub fn make_profile_params(owner: &[u8; 32]) -> Vec<u8> {