[openpgp] Re: text vs. binary in an OpenPGP "Signed Message"

[Andrew Gallagher <[e-mail]>]

On 3 Mar 2025, at 09:49, Justus Winter <[e-mail]> wrote:
> 
> - If we compute/verify a text signature, we transform the data stream on
>  the fly for hashing purposes, but the downstream consumer gets the
>  data as is.
> 
> In short, if you use Sequoia, what bytes go in come out again,
> unvalidated and unchanged.
> 
>> - If not, should a verifier that encounters (d) attempt to apply CRLF
>>  line endings to the LITb?
> 
> No.

We need to be careful to distinguish between canonicalisation of the signature subject (i.e. the data on the wire that a receiver can read directly) and of the “type-specific data” that is passed into the signature hash function. The point of type 1 signatures is that the type-specific data is independent of which newline convention (if any) has been applied to the subject. So for the above question, perhaps we should clarify that the wire format of the subject SHOULD NOT be altered by the receiving implementation, but the type-specific data passed to the signature verification MUST still be normalised.

A