Trying to follow the instructions here (https://www.linuxjournal.com/content/better-raspberry-pi-streaming-solution) but can't get their repository to work. I'm using stretch on a Pi3.

I changed my /etc/sources.list to include this line; deb http://www.linux-projects.org/listing/uv4l_repo/raspbian/stretch stretch main

Added the key using; curl http://www.linux-projects.org/listing/uv4l_repo/lrkey.asc | sudo apt-key add -

But when I try to run sudo apt-get update I get this error; W: GPG error: http://www.linux-projects.org/listing/uv4l_repo/raspbian/stretch stretch InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 978FA72DF442B950 W: The repository 'http://www.linux-projects.org/listing/uv4l_repo/raspbian/stretch stretch InRelease' is not signed. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.

Can anyone help me with this?

1 Answer 1


It seems the lrkey.asc file at that repo location does not contain the all the keys.

$ curl -s http://www.linux-projects.org/listing/uv4l_repo/lrkey.asc |gpg --list-packets |grep keyid
    keyid: 99DA5D2AFCE635A4
:signature packet: algo 17, keyid 99DA5D2AFCE635A4
    keyid: D50B5ECAEDC71A89
:signature packet: algo 17, keyid 99DA5D2AFCE635A4

However, the repo seems to have a second key file, lpkey.asc which does include the keyid listed in your error message.

$ curl -s http://www.linux-projects.org/listing/uv4l_repo/lpkey.asc |gpg --list-packets - |grep 978FA72DF442B950
    keyid: 978FA72DF442B950
:signature packet: algo 1, keyid 978FA72DF442B950
    subpkt 16 len 8 (issuer key ID 978FA72DF442B950)
:signature packet: algo 1, keyid 978FA72DF442B950
    subpkt 16 len 8 (issuer key ID 978FA72DF442B950)

So, try this to add all the keys:

curl -s http://www.linux-projects.org/listing/uv4l_repo/lpkey.asc | sudo apt-key add -

And verify that the desired keyid has been loaded:

$sudo apt-key list 978FA72DF442B950
pub   rsa2048 2017-10-28 [SC]
      AB10 087C FB5F C026 36D1  5020 978F A72D F442 B950
uid           [ unknown] admin <[email protected]>
sub   rsa2048 2017-10-28 [E]

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