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From: Mark Friedenbach <mark@friedenbach.org>
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Date: Fri, 22 Sep 2017 15:07:33 -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

There is no harm in the value being a maximum off by a few bytes.

> On Sep 22, 2017, at 2:54 PM, Sergio Demian Lerner =
<sergio.d.lerner@gmail.com> wrote:
>=20
> If the variable size increase is only a few bytes, then three =
possibilities arise:
>=20
> - one should allow signatures to be zero padded (to reach the maximum =
size) and abandon strict DER encoding
>=20
> - one should allow spare witness stack elements (to pad the size to =
match the maximum size) and remove the cleanstack rule. But this is =
tricky because empty stack elements must be counted as 1 byte.
>=20
> - signers must loop the generation of signatures until the signature =
generated is of its maximum size.