On Mon, Jan 30, 2023 at 10:17 AM Pádraig Brady <p...@draigbrady.com> wrote: > On 29/01/2023 20:40, Jim Meyering wrote: > > Hi Pádraig! Happy new year (belatedly ;-). Hope you're well. > > > > I'd like our generated announcements to be able to include > > base64-encoded checksums without having to recommend verifying them > > using openbsd's cksum, so...
Thanks for the long reply. > This is so the checksums are shorter right? That was my primary motivation. > I.e. 4x/3 rather than the 2x for hex. > Playing devil's advocate, is the complexity of > generally using base64 for this worth it, since say a 512 bit checksum > would only reduce from 128 chars to 86 chars? IMHO, added complexity is small, so yes, it's worth it. > Also related to this is the use of variable length algorithms > (supported with the existing -l option). > A quick scan of https://www.keylength.com/ suggests newer algorithms > like blake2 blake3 sha3 with -l 256 may be sufficient for this use case > in which case the difference would only be 64 chars to 44 chars. > The following demos that, while also using existing tools: > > $ sha256sum < /dev/null | xxd -r -p | basenc --base16 > E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855 > $ sha256sum < /dev/null | xxd -r -p | basenc --base64 > 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= > > > I've begun writing the code to add --base64/-b support for GNU cksum, > > prompted by this thread: > > https://lists.gnu.org/r/diffutils-devel/2023-01/msg00015.html and the > > fact that OpenBSD already has this option (as -b): > > https://man.openbsd.org/cksum > > We originally considered this back at: > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=7313 > which showed ways to achieve this with existing tools. > Though if it was a common operation (like it would be for your use case), > and for the fact that openbsd already implements this, > then it would be worth adding an option. > > BTW I noted the following possible option when I recently refactored cksum: > > --digest_format={int, hex, base64, binary} > /* cksum output formats: > int (sum, and cksum default), > hex (rest default), > b64 (to reduce size), > bin (would auto suppress names? restrict to single argument? */ I'm not sure how --digest-format=int -a sha1 would work. Or --digest-format=bin -a sum But doing it that way does provide a way to override a prior --base64 option. Without that, is a --hex option warranted?
