Isto é o que eu recebo quando executando o apt-get update:
/root$ sudo apt-get update
Get:1 http://security.debian.org jessie/updates InRelease [1,507 B]
Get:2 http://cdn.debian.net jessie InRelease [1,507 B]
Get:3 http://cdn.debian.net jessie-updates InRelease [1,507 B]
Err http://security.debian.org jessie/updates InReleaset/lists/partial/security.debian.org_dists_jessie_updates_InRelease into data and signature failed
Err http://cdn.debian.net jessie InReleasep /var/lib/apt/lists/partial/cdn.debian.net_debian_dists_jessie_InRelease into data and signature failed
Err http://cdn.debian.net jessie-updates InReleaseib/apt/lists/partial/cdn.debian.net_debian_dists_jessie-updates_InRelease into data and signature failed
Fetched 4,521 B in 1s (4,271 B/s)
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://security.debian.org jessie/updates InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://cdn.debian.net jessie InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://cdn.debian.net jessie-updates InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
W: Failed to fetch http://cdn.debian.net/debian/dists/jessie/InRelease
W: Failed to fetch http://security.debian.org/dists/jessie/updates/InRelease
W: Failed to fetch http://cdn.debian.net/debian/dists/jessie-updates/InRelease
W: Some index files failed to download. They have been ignored, or old ones used instead.
Eu estava lendo sobre isso, mas ainda estou um pouco confuso com o funcionamento das chaves GPG com repos.
Cada repositório tem uma chave associada a ele que eu preciso ter confiado em minha máquina antes que as atualizações desse repositório sejam permitidas, certo? Então, se esse erro é causado por ter uma chave desatualizada, como importo a nova chave?
Edit: Também estou curioso porque diz "O arquivo de Clearsigned não é válido". Eu pensei que o Clearsign era apenas para embrulhar documentos de texto, não bolas de alcatrão, a menos que eu lesse isso errado.