Package: lintian
Version: 2.104.0
Control: clone -1 -2
Control: reassign -2 devscripts
Control: retitle -2 [uscan] deprecate upstream signatures made using weak hashes like MD5, SHA1, or RIPEMD160
Some upstream packages are signed with OpenPGP using old, deprecated
digest algorithms.
See for example xml2rfc having a recent signature made with SHA-1:
https://mailarchive.ietf.org/arch/msg/xml2rfc-dev/G89V9M7_qSGxDVBb0QpSIqzznVc/
If lintian is scanning a package that includes a cryptographic signature
from upstream, it should warn (or produce an error) if that signature
uses a weak cryptographic digest algorithm. In particular, MD5, SHA1,
and RIPEMD160 should all be considered weak.
likewise, uscan should provide at least a warning (perhaps an error) if
it fetches an OpenPGP signature that appears to be made using a weak
digest.
For both of these cases (uscan and lintian), I say "warn" by default
instead of "error" because of course a package with a weak signature
shouldn't be treated worse than a package with *no* signature.
Some OpenPGP implementations (like "sqop verify" or "sq verify", both
from sequoia) already deprecate recently-made SHA1 signatures.
If you're using gpgv to verify signatures, you can use the --weak-digest
argument, like so:
$ gpgv --weak-digest RIPEMD160 --weak-digest SHA1 --keyring debian/upstream/signing-key.pgp ../xml2rfc_3.5.0.orig.tar.gz.asc ../xml2rfc_3.5.0.orig.tar.gz
gpgv: Signature made Wed 18 Nov 2020 05:20:56 AM EST
gpgv: using RSA key 4E9B574B8FBB171A
gpgv: Note: signatures using the SHA1 algorithm are rejected
gpgv: Can't check signature: Invalid digest algorithm
2 $
(MD5 is already marked as a "weak digest" by default, so no need to
include it specifically)
Thanks for considering this!
--dkg
Attachment:
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Description: PGP signature