++

src/secmod_eddsa.ml

@@ -1,8 +1,8 @@
 open Syntax
 open Crypto
-open Mirage_crypto_ec
-open Config.Exchange_secmod_eddsa
 open Time
+open Mirage_crypto_ec
+module Cfg = Config.Exchange_secmod_eddsa
 
 type priv = Ed25519.priv
 type pub = Ed25519.pub
@@ -17,7 +17,7 @@ type key = {
 type t = {
   sm_key_priv: priv;
   sm_key_pub: pub;
-  keys: key list;
+  mutable keys: key list;
 }
 
 let time_abs_of_string s =
@@ -27,6 +27,15 @@ let time_abs_of_string s =
       let ts = Absolute.of_s (Int64.of_int n) in
       Some ts
 
+let t1_t2_of_filename fname =
+  match String.split_on_char '-' fname with
+  | [] -> Fmt.failwith "not possible"
+  | [ t1; t2 ] -> (
+      match (time_abs_of_string t1, time_abs_of_string t2) with
+      | None, _ | _, None -> None
+      | Some t1, Some t2 -> Some (t1, t2))
+  | _ -> None
+
 let time_abs_to_string abs =
   abs
   |> Timestamp.of_absolute
@@ -35,47 +44,46 @@ let time_abs_to_string abs =
   |> Int64.to_int
   |> string_of_int
 
+let key_filename k =
+  let t1 = time_abs_to_string k.t1 in
+  let t2 = time_abs_to_string k.t2 in
+  Fmt.str "%s-%s" t1 t2
+
 let read_key fname =
-  let fpath = Fpath.(v key_dir / fname) in
+  let fpath = Fpath.(v Cfg.key_dir / fname) in
   let* data = Bos.OS.File.read fpath |> unwrap_err_msg in
   EddsaPrivateKey.of_octets data
 
 let write_eddsa fname priv =
-  let fpath = Fpath.(v key_dir / fname) in
+  let fpath = Fpath.(v Cfg.key_dir / fname) in
   let data = EddsaPrivateKey.to_octets priv in
   Bos.OS.File.write fpath data |> unwrap_err_msg
 
-let write_key t =
-  let t1 = time_abs_to_string t.t1 in
-  let t2 = time_abs_to_string t.t2 in
-  let fname = Fmt.str "%s-%s" t1 t2 in
-  write_eddsa fname t.priv
+let write_key k = write_eddsa (key_filename k) k.priv
+let sort_keys l = List.sort (fun a b -> Absolute.compare a.t2 b.t2) l
 
 let split_in_periodes ~start ~end_ =
-  (* no overlap on first periode
-     this is to not generate a key valid in the past *)
+  (* no overlap on first periode *)
   let t1 = start in
-  let t2 = Absolute.add start duration in
+  let t2 = Absolute.add start Cfg.duration in
   let acc = [ (t1, t2) ] in
   let start = t2 in
   let rec go acc start end_ =
-    let t1 = Absolute.sub start overlap_duration in
-    let t2 = Absolute.add start duration in
+    let t1 = Absolute.sub start Cfg.overlap_duration in
+    let t2 = Absolute.add start Cfg.duration in
     if t2 > end_ then acc else go ((t1, t2) :: acc) t2 end_
   in
   go acc start end_
 
-let sort_keys l = List.sort (fun a b -> Absolute.compare a.t2 b.t2) l
-
 let gen_additional_keys_until_lookahead ~now l =
-  let l = sort_keys l in
+  (* try to _not_ generate keys with validity start in the past
+     (probably not important) *)
   let start =
-    let l_rev = List.rev l in
-    match l_rev with
+    match List.rev (sort_keys l) with
     | [] -> now
-    | hd :: _ -> Absolute.sub hd.t2 overlap_duration
+    | hd :: _ -> Absolute.sub hd.t2 Cfg.overlap_duration
   in
-  let end_ = Absolute.add now lookahead_sign in
+  let end_ = Absolute.add now Cfg.lookahead_sign in
   let periodes = split_in_periodes ~start ~end_ in
   let new_keys =
     List.map
@@ -90,39 +98,22 @@ let check_periodes _l =
   (* TODO *)
   Ok ()
 
-let purge _t =
-  (* TODO *)
-  Ok ()
-
-let purge_outdated ~now l =
-  let+ l =
-    list_map
-      (fun t ->
-        if Absolute.compare now t.t2 >= 0 then
-          let* () = purge t in
-          Ok None
-        else Ok (Some t))
-      l
-  in
-  List.filter_map Fun.id l
-
+(* we load sm_key separately
+   we don't accept non-key files in key_dir *)
 let load_key fpath =
   let fname = Fpath.filename fpath in
-  if fname = sm_priv_key then Ok None
-  else
-    match String.split_on_char '-' fname with
-    | [] -> Fmt.failwith "not possible"
-    | [ t1; t2 ] -> (
-        match (time_abs_of_string t1, time_abs_of_string t2) with
-        | None, _ | _, None -> Fmt.error "invalid filename `%s`" fname
-        | Some t1, Some t2 ->
-            let* priv = read_key fname in
-            let pub = EddsaPrivateKey.pub_of_priv priv in
-            Ok (Some { priv; pub; t1; t2 }))
-    | _ -> Ok None
+  match fname = Cfg.sm_priv_key with
+  | true -> Ok None
+  | false -> (
+      match t1_t2_of_filename fname with
+      | None -> Fmt.error "invalid filename `%s`" fname
+      | Some (t1, t2) ->
+          let* priv = read_key fname in
+          let pub = EddsaPrivateKey.pub_of_priv priv in
+          Ok (Some { priv; pub; t1; t2 }))
 
 let load () =
-  let dir = Fpath.v key_dir in
+  let dir = Fpath.v Cfg.key_dir in
   let* b = Bos.OS.Dir.create ~mode:0o700 dir |> unwrap_err_msg in
   if b then
     Logs.info (fun m -> m "secmod_eddsa: created directory `%a`" Fpath.pp dir);
@@ -134,7 +125,7 @@ let load () =
   match keys with
   | [] -> Ok None
   | _l ->
-      let* sm_key_priv = read_key sm_priv_key in
+      let* sm_key_priv = read_key Cfg.sm_priv_key in
       let sm_key_pub = EddsaPrivateKey.pub_of_priv sm_key_priv in
       Ok (Some { sm_key_priv; sm_key_pub; keys })
 
@@ -145,36 +136,63 @@ let init () =
     | Some t -> Ok t
     | None ->
         let sm_key_priv, sm_key_pub = Mirage_crypto_ec.Ed25519.generate () in
-        let* () = write_eddsa sm_priv_key sm_key_priv in
+        let* () = write_eddsa Cfg.sm_priv_key sm_key_priv in
         Ok { sm_key_priv; sm_key_pub; keys= [] }
   in
   let now = Absolute.of_ptime (Ptime_clock.now ()) in
-  let* keys = purge_outdated ~now t.keys in
-  let* () = check_periodes keys in
-  let new_keys = gen_additional_keys_until_lookahead ~now keys in
+  let* () = check_periodes t.keys in
+  let new_keys = gen_additional_keys_until_lookahead ~now t.keys in
   let* () = list_iter write_key new_keys in
-  let keys = keys @ new_keys in
-  let keys = sort_keys keys in
+  let keys = sort_keys (t.keys @ new_keys) in
   let t = { t with keys } in
   Ok t
 
+(* --- *)
+
 let t =
   match init () with
   | Error e -> Fmt.failwith "secmod_eddsa initialization failure: %s." e
   | Ok t -> t
 
-(*
-  - sign
-  - expose future_sk list
-  - purge
-  - revoke
+let sm_key_pub = t.sm_key_pub
+let keys () = List.map (fun { priv= _; pub; t1; t2 } -> (pub, t1, t2)) t.keys
+let sign_with_sm_key s = EddsaSignature.sign ~key:t.sm_key_priv s
+
+let find_key pub =
+  List.find_opt (fun k -> k.pub = pub) t.keys
+  |> Option.to_result ~none:"key not found"
+
+let sign ~pub s =
+  let+ k = find_key pub in
+  let data = EddsaSignature.sign ~key:k.priv s in
+  data
+
+let delete_key pub =
+  let* k = find_key pub in
+  let l = List.filter (fun k -> k.pub <> pub) t.keys in
+  t.keys <- l;
+  (* rm file *)
+  let fname = key_filename k in
+  let fpath = Fpath.(v Cfg.key_dir / fname) in
+  let* () = Bos.OS.File.delete ~must_exist:true fpath |> unwrap_err_msg in
+  Ok ()
+
+let delete_outdated ~now =
+  t.keys
+  |> List.filter (fun k -> Absolute.compare now k.t2 >= 0)
+  |> List.map (fun k -> k.pub)
+  |> list_iter delete_key
+
+(* TODO
+  - sign: check time
   - schedule tasks
   - !lock
 
-  todo taler doc/config is confusing
+  taler doc/config is confusing
   how is computed stamp_expire stamp_end
   what to do of 'Exchange.signkey_legal_duration'
-  => (??)
+  =>
     stamp_expire = stamp_start + duration
     stamp_end = stamp_start + signkey_legal_duration
+    (not sure about it)
 *)