greetings for UBUNTU community
i used Ubuntu 16.04 and had a problem at the time of update
W: GPG error: http://dl.bintray.com/aluxian/deb stable Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY E61DA9241537994D
E: The repository ‘http://dl.bintray.com/aluxian/deb stable Release’ is not signed.
N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://downloads.metasploit.com/data/releases/metasploit-framework/apt lucid InRelease: The following signatures were invalid: KEYEXPIRED 1474234115 KEYEXPIRED 1474234115 KEYEXPIRED 1474234115
E: The repository ‘http://downloads.metasploit.com/data/releases/metasploit-framework/apt lucid InRelease’ is not signed.
N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
what should i do ?