As also found at issue #571, am reporting again (per dev instructions) as is a known issue and must be resolved manually (dev noted that “our CDN can get into a bad state sometimes”).
Commands being run from within the US.
When building upon base nvidia/cuda:10.1-devel-ubuntu18.04, receive the following at the apt-get update stage:
...
Err:2 http://security.ubuntu.com/ubuntu bionic-security InRelease
At least one invalid signature was encountered.
Err:3 http://archive.ubuntu.com/ubuntu bionic InRelease
At least one invalid signature was encountered.
Get:9 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
Err:9 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
At least one invalid signature was encountered.
Get:10 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]
Err:10 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
At least one invalid signature was encountered.
Reading package lists...
W: GPG error: https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64 Release: At least one invalid signature was encountered.
E: The repository 'https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64 Release' is not signed.
W: GPG error: https://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1804/x86_64 Release: At least one invalid signature was encountered.
E: The repository 'https://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1804/x86_64 Release' is not signed.
W: GPG error: http://security.ubuntu.com/ubuntu bionic-security InRelease: At least one invalid signature was encountered.
E: The repository 'http://security.ubuntu.com/ubuntu bionic-security InRelease' is not signed.
W: GPG error: http://archive.ubuntu.com/ubuntu bionic InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic InRelease' is not signed.
W: GPG error: http://archive.ubuntu.com/ubuntu bionic-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' is not signed.
W: GPG error: http://archive.ubuntu.com/ubuntu bionic-backports InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-backports InRelease' is not signed. ...