Source file `pvss_secp256k1.ml`

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(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

open Secp256k1_group

module G : Pvss.CYCLIC_GROUP = struct
  module Z_m = struct
    include Group.Scalar

    let n = Group.order

    let ( + ) = Group.Scalar.add

    let ( * ) = Group.Scalar.mul

    let ( - ) = Group.Scalar.sub

    let ( = ) = Group.Scalar.equal

    let inv = Group.Scalar.inverse
  end

  include Group

  let name = "secp256k1"

  (* This pvss algorithm assumes the public keys of the participants receiving
     shares are based on g2, so we set g2 to Group.g to match regular Secp256k1
     public keys.
  *)
  let g1 = Group.h

  let g2 = Group.g

  (* We use a multiplicative notation in the pvss module, but
     secp256k1 usually uses an additive notation. *)
  let ( * ) = Group.(( + ))

  let pow x n = Group.mul n x

  let of_bits b = Option.catch (fun () -> Group.of_bits_exn b)
end

include Pvss.MakePvss (G)

let convert_encoding de1 de2 x =
  Data_encoding.Binary.of_bytes_exn
    de2
    (Data_encoding.Binary.to_bytes_exn de1 x)

let generate_keys ?(seed = Hacl.Rand.gen 32) () =
  let s =
    Secp256k1_group.Group.Scalar.of_bits_exn
      (Bigstring.of_bytes seed |> Bigstring.to_string)
  in
  let sk =
    convert_encoding Secp256k1_group.Group.Scalar.encoding Secret_key.encoding s
  in
  let pk = Secret_key.to_public_key sk in
  (pk, sk)