I maintain a small debian repository for my employer, and we have been facing issues lately due to the SHA1 deprecation.
We sign our packages with a 4096bit RSA key. For signing the repository, I used this GPG command:
root@name-not-revealed.com:/var/www/debian/dists/xenial# cat /root/.gnupg/gpg.conf
cert-digest-algo SHA512
digest-algo SHA512
disable-cipher-algo SHA1
default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 ZLIB BZIP2 ZIP Uncompressed
personal-digest-preferences SHA512
root@name-not-revealed.com:/var/www/debian/dists/xenial# gpg -a --detach-sign \
--personal-digest-preferences SHA512 \
--default-key=XXXXXXXX -o Release.gpg Release
Checking the signature to make sure it isn't using SHA1:
root@name-not-revealed.com:/var/www/debian/dists/xenial# gpg --list-packets Release.gpg
:signature packet: algo 1, keyid XXXXXXXXXXXXXXXX
version 4, created 1484090425, md5len 0, sigclass 0x00
digest algo 10, begin of digest 3f 00
hashed subpkt 2 len 4 (sig created 2017-01-10)
subpkt 16 len 8 (issuer key ID XXXXXXXXXXXXXXXX)
data: [4095 bits]
As far as I'm informed, the bit about "digest algo 10" means that it's using SHA512 for digest. SHA1 would be "digest algo 2".
On a client, I did the following:
root@othermachine:/root# echo "deb https://debian.name-not-revealed.com xenial main" >> /etc/apt/sources.list
root@othermachine:/root# apt-key adv --keyserver pool.sks-keyservers.net --recv-keys 0xXXXXXXXX
root@othermachine:/root# apt-get update
Hit:1 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial InRelease
Get:2 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Get:3 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Hit:4 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:5 http://ppa.launchpad.net/ondrej/php/ubuntu xenial InRelease
Ign:6 https://debian.name-not-revealed.com xenial InRelease
Hit:7 https://debian.name-not-revealed.com xenial Release
Fetched 204 kB in 12s (15.9 kB/s)
Reading package lists... Done
W: https://debian.name-not-revealed.com/dists/xenial/Release.gpg: Signature by key 20F6C08B949AF3A95ECD7F6FDCDE5A8971317416 uses weak digest algorithm (SHA1)
Why does this warning still appear? Why does apt-get think I'm still using SHA1?
At first I assumed the key to be the culprit, so I created a new one according to this GPG migration guide: https://wiki.ubuntu.com/SecurityTeam/GPGMigration
However I'm still getting the "weak digest" warning. I'm at the end of my wits. What am I doing wrong?
