From 7b6d73a61ba050fe33f4ff4981ce4b3966d5d38f Mon Sep 17 00:00:00 2001
From: swrup <swrup@protonmail.com>
Date: Mon, 23 Feb 2026 10:59:36 +0100
Subject: [PATCH]

---
 src/denomination.ml | 42 ++++++++++++++++++++++++++++++++----------
 src/http_info.ml    | 10 +++++-----
 2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/src/denomination.ml b/src/denomination.ml
index ec5f7905..8c7fded4 100644
--- a/src/denomination.ml
+++ b/src/denomination.ml
@@ -16,7 +16,7 @@ type t = {
   master_sig: Signatures.DenominationKeyValidity.t;
 }
 
-let make_denom_group denominations =
+let make_denom_group_sorted denominations =
   let open Syntax in
   let ht = Hashtbl.create 0xff in
   List.iter
@@ -72,19 +72,41 @@ let make_denom_group denominations =
         Hashtbl.replace ht k (v :: l))
       denominations
   in
-  Hashtbl.to_seq ht
-  |> List.of_seq
-  |> List.map
-       (fun
-         ((value, fee_withdraw, fee_deposit, fee_refresh, fee_refund), denoms)
-       ->
-         Api.DenomGroup.Rsa
-           Api.RsaDenomGroup.
+
+  (* ! important for /keys .exchange_sig
+     each group must be ordered in _reverse_ chronological order
+     order of groups to compute hash, must be the same as the order
+     in /keys .denominations *)
+  let open Api in
+  let open DenomGroup in
+  let open RsaDenomGroup in
+  let open RsaDenom in
+  let cmp_denom b a = Timestamp.compare a.stamp_start b.stamp_start in
+  let cmp_group =
+    let cmp_amount a b =
+      let open Amount in
+      match Int64.unsigned_compare a.value b.value with
+      | 0 -> Int32.unsigned_compare a.fraction b.fraction
+      | n -> n
+    in
+    fun (Rsa a) (Rsa b) -> cmp_amount a.value b.value
+  in
+  let l =
+    Hashtbl.to_seq ht
+    |> List.of_seq
+    |> List.map
+         (fun
+           ((value, fee_withdraw, fee_deposit, fee_refresh, fee_refund), denoms)
+         ->
+           Rsa
              {
-               denoms;
+               denoms= List.sort cmp_denom denoms;
                value;
                fee_withdraw;
                fee_deposit;
                fee_refresh;
                fee_refund;
              })
+    |> List.sort cmp_group
+  in
+  l
diff --git a/src/http_info.ml b/src/http_info.ml
index f508a52f..4b425e1e 100644
--- a/src/http_info.ml
+++ b/src/http_info.ml
@@ -92,7 +92,7 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
           (fun v -> Timestamp.compare v.Denomination.stamp_start timestamp >= 0)
           denom_l
   in
-  let* denominations = Denomination.make_denom_group denom_l in
+  let* denominations = Denomination.make_denom_group_sorted denom_l in
 
   let* signkeys = Keys.signkeys () in
   let signkeys =
@@ -110,13 +110,13 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
     | sk :: _ -> Ok sk.SignKey.key
   in
 
-  (* TODO *)
-  (* Compact eddsa signature over the contatentation of all of the master_sigs
+  (* eddsa signature over the contatentation of all of the master_sigs
      (in reverse chronological order by group) in the arrays under "denominations" *)
   let exchange_sig =
     let hc =
-      denom_l
-      |> List.map (fun dn -> dn.Denomination.master_sig)
+      denominations
+      |> List.map (fun (DenomGroup.Rsa g) -> g.RsaDenomGroup.denoms)
+      |> List.concat_map (List.map (fun dn -> dn.RsaDenom.master_sig))
       |> List.map Signatures.DenominationKeyValidity.to_octets
       |> String.concat ""
       |> Hash.H64.hash