context_binary_proof.ml
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type error += Expected_binary_proof
let () =
register_error_kind
`Permanent
~id:"Expected_binary_proof"
~title:"Expected binary proof"
~description:"An invalid proof has been submitted"
Data_encoding.empty
(function Expected_binary_proof -> Some () | _ -> None)
(fun () -> Expected_binary_proof)
(* TODO: https://gitlab.com/tezos/tezos/-/issues/4386 Extracted and
adapted from {!Tezos_context_memory}. Ideally, this function should
be exported there.
In a nutshell, the context library exposed by the environment is
implemented such that it can verify proofs generated by both
[Context] and [Context_binary], and the only thing that
differentiate these proofs from its perspective is the second bit
of the [version] field of the proof.
To ensure we only consider proofs computed against a binary tree,
we check said bit. This prevents a 32-ary proof to be accepted by
the protocol in the case where a given key-value store has the same
hash with both [Context] and [Context_binary] (something that
happens when the tree contains only one entry). *)
let check_is_binary proof =
let extract_bit v mask = Compare.Int.(v land mask <> 0) in
let binary_mask = 0b10 in
let is_binary = extract_bit proof.Context.Proof.version binary_mask in
error_unless is_binary Expected_binary_proof