On Fri, Sep 22, 2017 at 2:54 PM, Sergio Demian Lerner via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> If the variable size increase is only a few bytes, then three
> possibilities arise:
>
> - one should allow signatures to be zero padded (to reach the maximum
> size) and abandon strict DER encoding
>
> - 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.
>
> - signers must loop the generation of signatures until the signature
> generated is of its maximum size.
>

Or (my preference);

- Get rid of DER encoding alltogether and switch to fixed size signatures.

Cheers,

-- 
Pieter