Election.Make now takes ELECTION_DATA

src/booth/booth.ml

@@ -103,11 +103,11 @@ end
 let encryptBallot params cred plaintext () =
   let module P = (val params : ELECTION_DATA) in
   let module G = P.G in
-  let module E = Election.Make (G) (LwtJsRandom) in
+  let module E = Election.Make (P) (LwtJsRandom) in
   let module CD = Credential.MakeDerive (G) in
   let sk = CD.derive P.election.e_params.e_uuid cred in
-  lwt randomness = E.make_randomness P.election () in
-  lwt b = E.create_ballot P.election ~sk randomness plaintext () in
+  lwt randomness = E.make_randomness () () in
+  lwt b = E.create_ballot ~sk randomness plaintext () in
   let s = string_of_ballot G.write b in
   setTextarea "ballot" s;
   setNodeById "ballot_tracker" (sha256_b64 s);

src/lib/election.ml

@@ -54,7 +54,8 @@ let question_length q =
 
 (** Homomorphic elections *)
 
-module Make (G : GROUP) (M : RANDOM) = struct
+module Make (W : ELECTION_DATA) (M : RANDOM) = struct
+  open W
   open G
 
   type 'a m = 'a M.t
@@ -63,7 +64,6 @@ module Make (G : GROUP) (M : RANDOM) = struct
 
   type elt = G.t
 
-  type t = elt election
   type private_key = Z.t
   type public_key = elt
 
@@ -84,9 +84,9 @@ module Make (G : GROUP) (M : RANDOM) = struct
       beta = c1.beta *~ c2.beta;
     }
 
-  let neutral_ciphertext e = Array.map (fun q ->
+  let neutral_ciphertext () = Array.map (fun q ->
     Array.make (question_length q) dummy_ciphertext
-  ) e.e_params.e_questions
+  ) election.e_params.e_questions
 
   let combine_ciphertexts = Array.mmap2 eg_combine
 
@@ -438,10 +438,10 @@ module Make (G : GROUP) (M : RANDOM) = struct
        let blank_proof = None in
        return {choices; individual_proofs; overall_proof; blank_proof}
 
-  let make_randomness e =
+  let make_randomness () =
     sswap (Array.map (fun q ->
       Array.init (question_length q) (fun _ -> random G.q)
-    ) e.e_params.e_questions)
+    ) election.e_params.e_questions)
 
   let make_sig_prefix zkp commitment =
     "sig|" ^ zkp ^ "|" ^ G.to_string commitment ^ "|"
@@ -457,8 +457,8 @@ module Make (G : GROUP) (M : RANDOM) = struct
       ) (Array.to_list answers)
     ) |> Array.of_list
 
-  let create_ballot e ?sk r m =
-    let p = e.e_params in
+  let create_ballot ?sk r m =
+    let p = election.e_params in
     let sk, zkp =
       match sk with
       | None -> None, ""
@@ -479,7 +479,7 @@ module Make (G : GROUP) (M : RANDOM) = struct
     ) >>= fun signature ->
     return {
       answers;
-      election_hash = e.e_fingerprint;
+      election_hash = election.e_fingerprint;
       election_uuid = p.e_uuid;
       signature;
     }
@@ -503,10 +503,10 @@ module Make (G : GROUP) (M : RANDOM) = struct
        eg_disj_verify y d zkp a.overall_proof sumc
     | _, _ -> false
 
-  let check_ballot e b =
-    let p = e.e_params in
+  let check_ballot b =
+    let p = election.e_params in
     b.election_uuid = p.e_uuid &&
-    b.election_hash = e.e_fingerprint &&
+    b.election_hash = election.e_fingerprint &&
     let ok, zkp = match b.signature with
       | Some {s_public_key = y; s_challenge; s_response} ->
         let zkp = G.to_string y in

src/lib/election.mli

@@ -29,6 +29,6 @@ val get_group : Yojson.Safe.json election -> (module ELECTION_DATA)
 
 val question_length : question -> int
 
-module Make (G : GROUP) (M : RANDOM) :
-  ELECTION with type elt = G.t and type 'a m = 'a M.t
+module Make (W : ELECTION_DATA) (M : RANDOM) :
+  ELECTION with type elt = W.G.t and type 'a m = 'a M.t
 (** Implementation of {!Signatures.ELECTION}. *)

src/lib/signatures.mli

@@ -141,7 +141,6 @@ module type ELECTION = sig
 
   type elt
 
-  type t = elt election
   type private_key = Z.t
   type public_key = elt
 
@@ -150,7 +149,7 @@ module type ELECTION = sig
   type ciphertext = elt Serializable_t.ciphertext array array
   (** A ciphertext that can be homomorphically combined. *)
 
-  val neutral_ciphertext : t -> ciphertext
+  val neutral_ciphertext : unit -> ciphertext
   (** The neutral element for [combine_ciphertext] below. *)
 
   val combine_ciphertexts : ciphertext -> ciphertext -> ciphertext
@@ -172,18 +171,17 @@ module type ELECTION = sig
   type randomness
   (** Randomness needed to create a ballot. *)
 
-  val make_randomness : t -> randomness m
+  val make_randomness : unit -> randomness m
   (** Creates randomness for [create_ballot] below. The result can be
       kept for Benaloh-style auditing. *)
 
-  val create_ballot : t -> ?sk:private_key ->
-    randomness -> plaintext -> ballot m
+  val create_ballot : ?sk:private_key -> randomness -> plaintext -> ballot m
   (** [create_ballot r answers] creates a ballot, or raises
       [Invalid_argument] if [answers] doesn't satisfy the election
       constraints. The private key, if given, will be used to sign
       the ballot. *)
 
-  val check_ballot : t -> ballot -> bool
+  val check_ballot : ballot -> bool
   (** [check_ballot b] checks all the cryptographic proofs in [b]. All
       ballots produced by [create_ballot] should pass this check. *)
 

src/tool/tool_election.ml

@@ -59,7 +59,7 @@ let parse_params p =
 module Make (P : PARSED_PARAMS) : S = struct
 
   open P
-  module E = Election.Make (G) (DirectRandom)
+  module E = Election.Make (P) (DirectRandom)
 
   module KG = Trustees.MakeSimple (G) (DirectRandom)
 
@@ -135,7 +135,7 @@ module Make (P : PARSED_PARAMS) : S = struct
   )
 
   let cast (b, hash) =
-    if Lazy.force check_signature_present b && E.check_ballot election b
+    if Lazy.force check_signature_present b && E.check_ballot b
     then ()
     else Printf.ksprintf failwith "ballot %s failed tests" hash
 
@@ -150,7 +150,7 @@ module Make (P : PARSED_PARAMS) : S = struct
         | Some ballots ->
            List.fold_left (fun accu (b, _) ->
                E.combine_ciphertexts (E.extract_ciphertext b) accu
-             ) (E.neutral_ciphertext election) ballots,
+             ) (E.neutral_ciphertext ()) ballots,
            List.length ballots
       )
 
@@ -161,8 +161,8 @@ module Make (P : PARSED_PARAMS) : S = struct
         CD.derive election.e_params.e_uuid cred
       )
     in
-    let b = E.create_ballot election ?sk (E.make_randomness election) ballot in
-    assert (E.check_ballot election b);
+    let b = E.create_ballot ?sk (E.make_randomness ()) ballot in
+    assert (E.check_ballot b);
     string_of_ballot G.write b
 
   let decrypt privkey =

src/tool/tool_js_pd.ml

@@ -68,7 +68,7 @@ let compute_partial_decryption _ =
   Js.Opt.option !election >>= fun e ->
   let election = Election.(get_group (of_string e)) in
   let module P = (val election) in
-  let module E = Election.Make (P.G) (DirectRandom) in
+  let module E = Election.Make (P) (DirectRandom) in
   Js.Opt.option !encrypted_tally >>= fun e ->
   let encrypted_tally = encrypted_tally_of_string P.G.read e in
   document##getElementById (Js.string "private_key") >>= fun e ->

src/tool/tool_verifydiff.ml

@@ -113,7 +113,7 @@ let verifydiff dir1 dir2 =
   (* the public keys / threshold parameters must be valid *)
   let module ED = (val Election.(get_group (of_string election))) in
   let open ED in
-  let module E = Election.Make (G) (DirectRandom) in
+  let module E = Election.Make (ED) (DirectRandom) in
   let y =
     match threshold with
     | None ->
@@ -172,7 +172,7 @@ let verifydiff dir1 dir2 =
     match load_from_file (ballot_of_string G.read) (dir / "ballots.jsons") with
     | None -> raise (VerifydiffError MissingBallots)
     | Some ballots ->
-       if not (List.for_all (E.check_ballot election) ballots) then
+       if not (List.for_all E.check_ballot ballots) then
          raise (VerifydiffError InvalidBallot);
        (* return the set of ballots indexed by the public keys used to sign *)
        List.fold_left (fun accu x ->

src/web/web_election.ml

@@ -36,7 +36,7 @@ module Make (D : ELECTION_DATA) (M : RANDOM with type 'a t = 'a Lwt.t) : WEB_ELE
     let uuid = D.election.e_params.e_uuid
 
     module G = D.G
-    module E = Election.Make (G) (M)
+    module E = Election.Make (D) (M)
 
     module B : WEB_BALLOT_BOX = struct
 
@@ -106,7 +106,7 @@ module Make (D : ELECTION_DATA) (M : RANDOM with type 'a t = 'a Lwt.t) : WEB_ELE
         match old_cred, old_record with
           | None, None ->
             (* first vote *)
-            if E.check_ballot D.election ballot then (
+            if E.check_ballot ballot then (
               let hash = sha256_b64 rawballot in
               Ocsipersist.add cred_table credential (Some hash) >>
               Ocsipersist.add ballots_table hash rawballot >>
@@ -119,7 +119,7 @@ module Make (D : ELECTION_DATA) (M : RANDOM with type 'a t = 'a Lwt.t) : WEB_ELE
           | Some h, Some (_, old_credential) ->
             (* revote *)
             if credential = old_credential then (
-              if E.check_ballot D.election ballot then (
+              if E.check_ballot ballot then (
                 Ocsipersist.remove ballots_table h >>
                 let hash = sha256_b64 rawballot in
                 Ocsipersist.add cred_table credential (Some hash) >>
@@ -212,7 +212,7 @@ module Make (D : ELECTION_DATA) (M : RANDOM with type 'a t = 'a Lwt.t) : WEB_ELE
               let ballot = ballot_of_string G.read rawballot in
               let ciphertext = E.extract_ciphertext ballot in
               return (n + 1, E.combine_ciphertexts accu ciphertext))
-            ballots_table (0, E.neutral_ciphertext D.election)
+            ballots_table (0, E.neutral_ciphertext ())
         in
         let tally = string_of_encrypted_tally G.write tally in
         Lwt_mutex.with_lock mutex (fun () ->

src/web/web_site.ml

@@ -1364,7 +1364,7 @@ let () =
       in
       let%lwt election = find_election uuid in
       let module W = (val Election.get_group election) in
-      let module E = Election.Make (W.G) (LwtRandom) in
+      let module E = Election.Make (W) (LwtRandom) in
       let%lwt pks =
         match%lwt Web_persist.get_threshold uuid with
         | Some tp ->
@@ -1402,7 +1402,7 @@ let handle_election_tally_release (uuid, ()) () =
       let%lwt election = find_election uuid in
       let%lwt metadata = Web_persist.get_election_metadata uuid in
       let module W = (val Election.get_group election) in
-      let module E = Election.Make (W.G) (LwtRandom) in
+      let module E = Election.Make (W) (LwtRandom) in
       if metadata.e_owner = Some u then (
         let%lwt npks, ntallied =
           match%lwt Web_persist.get_election_state uuid with