user@slate:~$ sudo apt-get update
[sudo] password for user: 
Hit:1 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease                                                                                      
Get:3 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease [94.5 kB]                                                                    
Ign:4 http://dl.google.com/linux/talkplugin/deb stable InRelease                                                               
Ign:6 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1504/x86_64  InRelease                                     
Get:7 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1504/x86_64  Release [186 B]
Get:5 http://dl.google.com/linux/talkplugin/deb stable Release [1,347 B]        
Hit:8 http://ppa.launchpad.net/ubuntu-mozilla-daily/firefox-aurora/ubuntu xenial InRelease                              
Get:9 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1504/x86_64  Release.gpg [181 B]                             
Get:10 http://dl.google.com/linux/talkplugin/deb stable Release.gpg [198 B]                    
Hit:11 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease                                      
Hit:12 http://ppa.launchpad.net/webupd8team/atom/ubuntu xenial InRelease 
Hit:13 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Fetched 96.4 kB in 0s (122 kB/s)
Reading package lists... Done
W: http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1504/x86_64/Release.gpg: Signature by key 889BEE522DA690103C4B085ED88C3D385C37D3BE uses weak digest algorithm (SHA1)
W: http://dl.google.com/linux/talkplugin/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
E: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/Release  No Hash entry in Release file /var/lib/apt/lists/partial/dl.google.com_linux_talkplugin_deb_dists_stable_Release which is considered strong enough for security purposes
E: Failed to fetch http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1504/x86_64/Release  No Hash entry in Release file /var/lib/apt/lists/partial/developer.download.nvidia.com_compute_cuda_repos_ubuntu1504_x86%5f64_Release which is considered strong enough for security purposes
E: Some index files failed to download. They have been ignored, or old ones used instead.