Here is the output before trying to import the key:
richard@lenovo:~$ apt-key list
/etc/apt/trusted.gpg.d/linrunner_ubuntu_tlp.gpg
-----------------------------------------------
pub rsa1024 2009-07-27 [SC]
2042 F03C 5FAB D0BA 2CED 4041 2B3F 92F9 02D6 5EFF
uid [ unknown] Launchpad PPA for linrunner
/etc/apt/trusted.gpg.d/nordvpn-keyring.gpg
------------------------------------------
pub rsa4096 2018-08-02 [SC]
BC54 80EF EC5C 081C E5BC FBE2 6B21 9E53 5C96 4CA1
uid [ unknown] NordVPN <[email protected]>
sub rsa4096 2018-08-02 [S]
/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
790B C727 7767 219C 42C8 6F93 3B4F E6AC C0B2 1F32
uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) <[email protected]>
/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092
uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <[email protected]>
/etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg
------------------------------------------------------
pub rsa4096 2018-09-17 [SC]
F6EC B376 2474 EDA9 D21B 7022 8719 20D1 991B C93C
uid [ unknown] Ubuntu Archive Automatic Signing Key (2018) <[email protected]>
After inputting the ‘sudo apt-key add brave-core.asc’ command (and receiving the “OK” confirmation, here is the output:
richard@lenovo:~$ apt-key list
/etc/apt/trusted.gpg
--------------------
pub rsa4096 2018-10-15 [SC] [expires: 2020-02-05]
D8BA D4DE 7EE1 7AF5 2A83 4B2D 0BB7 5829 C2D4 E821
uid [ unknown] Brave Software <[email protected]>
sub rsa4096 2019-10-17 [S] [expires: 2020-05-14]
/etc/apt/trusted.gpg.d/linrunner_ubuntu_tlp.gpg
-----------------------------------------------
pub rsa1024 2009-07-27 [SC]
2042 F03C 5FAB D0BA 2CED 4041 2B3F 92F9 02D6 5EFF
uid [ unknown] Launchpad PPA for linrunner
/etc/apt/trusted.gpg.d/nordvpn-keyring.gpg
------------------------------------------
pub rsa4096 2018-08-02 [SC]
BC54 80EF EC5C 081C E5BC FBE2 6B21 9E53 5C96 4CA1
uid [ unknown] NordVPN <[email protected]>
sub rsa4096 2018-08-02 [S]
/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
790B C727 7767 219C 42C8 6F93 3B4F E6AC C0B2 1F32
uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) <[email protected]>
/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092
uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <[email protected]>
/etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg
------------------------------------------------------
pub rsa4096 2018-09-17 [SC]
F6EC B376 2474 EDA9 D21B 7022 8719 20D1 991B C93C
uid [ unknown] Ubuntu Archive Automatic Signing Key (2018) <[email protected]>