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From: Mark Friedenbach <mark@friedenbach.org>
In-Reply-To: <CAKzdR-pnvystx5H+P+OCXm73aVmWdyesCymerSgx=pCuXx+YGA@mail.gmail.com>
Date: Fri, 22 Sep 2017 14:39:45 -0700
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To: Sergio Demian Lerner <sergio.d.lerner@gmail.com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] cleanstack alt stack & softfork improvements
 (Was: Merkle branch verification & tail-call semantics for generalized
 MAST)
Precedence: list

You generally know the witness size to within a few bytes right before =
signing. Why would you not? You know the size of ECDSA signatures. You =
can be told the size of a hash preimage by the other party. It takes =
some contriving to come up with a scheme where one party has =
variable-length signatures of their chosing

> On Sep 22, 2017, at 2:32 PM, Sergio Demian Lerner =
<sergio.d.lerner@gmail.com> wrote:
>=20
> But generally before one signs a transaction one does not know the =
signature size (which may be variable). One can only estimate the =
maximum size.=20