sapling_validator.ml
(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2019-2020 Nomadic Labs <contact@nomadic-labs.com> *)
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(*****************************************************************************)
(* 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)))