sapling_validator.ml
(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2019-2020 Nomadic Labs <contact@nomadic-labs.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. *)
(* *)
(*****************************************************************************)
(* Check that each nullifier is not already present in the state and add it.
Important to avoid spending the same input twice in a transaction. *)
let rec check_and_update_nullifiers ctxt state inputs =
match inputs with
| [] ->
return (ctxt, Some state)
| input :: inputs -> (
Sapling_storage.nullifiers_mem ctxt state Sapling.UTXO.(input.nf)
>>=? function
| (ctxt, true) ->
return (ctxt, None)
| (ctxt, false) ->
let state =
Sapling_storage.nullifiers_add state Sapling.UTXO.(input.nf)
in
check_and_update_nullifiers ctxt state inputs )
let verify_update :
Raw_context.t ->
Sapling_storage.state ->
Sapling_repr.transaction ->
string ->
(Raw_context.t * (Int64.t * Sapling_storage.state) option) tzresult Lwt.t =
fun ctxt state transaction key ->
(* Check the transaction *)
(* To avoid overflowing the balance, the number of inputs and outputs must be
bounded.
Ciphertexts' memo_size must match the state's memo_size.
These constraints are already enforced at the encoding level. *)
assert (Compare.Int.(List.compare_length_with transaction.inputs 5208 <= 0)) ;
assert (Compare.Int.(List.compare_length_with transaction.outputs 2019 <= 0)) ;
let pass =
List.for_all
(fun output ->
Compare.Int.(
Sapling.Ciphertext.get_memo_size Sapling.UTXO.(output.ciphertext)
= state.memo_size))
transaction.outputs
in
if not pass then return (ctxt, None)
else
(* Check the root is a recent state *)
Sapling_storage.root_mem ctxt state transaction.root
>>=? fun pass ->
if not pass then return (ctxt, None)
else
check_and_update_nullifiers ctxt state transaction.inputs
>|=? function
| (ctxt, None) ->
(ctxt, None)
| (ctxt, Some state) ->
Sapling.Verification.with_verification_ctx (fun vctx ->
let pass =
(* Check all the output ZK proofs *)
List.for_all
(fun output -> Sapling.Verification.check_output vctx output)
transaction.outputs
in
if not pass then (ctxt, None)
else
let pass =
(* Check all the input Zk proofs and signatures *)
List.for_all
(fun input ->
Sapling.Verification.check_spend
vctx
input
transaction.root
key)
transaction.inputs
in
if not pass then (ctxt, None)
else
let pass =
(* Check the signature and balance of the whole transaction *)
Sapling.Verification.final_check vctx transaction key
in
if not pass then (ctxt, None)
else
(* update tree *)
let list_to_add =
List.map
(fun output ->
Sapling.UTXO.(output.cm, output.ciphertext))
transaction.outputs
in
let state = Sapling_storage.add state list_to_add in
(ctxt, Some (transaction.balance, state)))