Você pode importar a chave manualmente seguindo o método alternativo publicado no site oficial :
If this doesn’t work, it might be due to a firewall blocking port 11371. Alternatively, you can search for 0x381BA480 at http://keys.gnupg.net (check “Show PGP Fingerprints”), check the fingerprint and copy the key block into a plain text file, named, for instance, jranke_cran.asc wich you add to apt with apt-key add.
Depois da string: 0x381BA480 aqui pesquise a chave: Resultado
-----BEGIN PGP PUBLIC KEY BLOCK----- Version: SKS 1.1.5 Comment: Hostname: keys.nerds.lu mQGiBEXUFiURBADkTqPqcRYdLIguhC6fnwTvIxdkoN1UEBuPR6NYW4iJzvRSas/g5bPo5ZxE 2i5BXiuVfYrSk/YiU+/lc0K6VYNDygbOfpBgGGhtfzYfFRTYNq8QsdD8L8BMYtOu5rYo5BYt a0vuantIS9mn9QnH7885uy5tX/TXO7ICYVHxnFNr2wCguNtMdz9+DRQ38n4iiHzTtj/7UHsD /0+0TLHHvY1FfakVinamR9oCm9uH9PmkGTy6jRnrvg5Z+TTgygiDdTBKPc1TqpFgoFtqh8G5 DpDPbyh5GzBj8Ky1mBJb3bMwy2RUth1cztHEWI36xuCl+KrLtA4OYuCwJJZhOWDIO9aO2LW5 kJhIwIuvSrEtOgTxpzy82g7eEzvLBADUrQ01fj+9VDrO2Vept8jtaGK+4kW3cBAG/UbOrTjt 63VurXwyvNb6q7hKFUaVH42Fc0e64F217mutCyftPWYJwY4SR8hUmjEM/SYcezUDWWvVxmkF 8M4rMhHa0j+q+et3mTKwgxehQO9hLUqRebnmJuwNqNJKb9izsPqmh83Zo7Q7Sm9oYW5uZXMg UmFua2UgKENSQU4gRGViaWFuIGFyY2hpdmUpIDxqcmFua2VAdW5pLWJyZW1lbi5kZT6IRgQQ EQIABgUCRdQ+nQAKCRAvD04U9kmvkJ3+AJ4xLMELB/fT1AwtR1azcH0lKg/TegCdEvtp3SUf aHP3Jvg2CkzTZOatfFuIRgQQEQIABgUCS4VoCgAKCRDvfNpxC67+5ZFyAKCAzgPTqM6sSMhB iaZbNCpiVtwDrQCgjMy+iqPm7SVOCq0XJsCCbxymfB+IXgQTEQIAHgUCRdQWJQIbAwYLCQgH AwIDFQIDAxYCAQIeAQIXgAAKCRAG+Q3lOBukgM09AKCuapN6slttAFRjs2/mgtaMMwO9sgCf ZD2au39Oo8QLXZhZTipN8c7j9mM= =BRgm -----END PGP PUBLIC KEY BLOCK-----
Copie-o com seu editor de texto favorito e salve-o como: jranke_cran.asc
abra o terminal e execute:
# apt-key add jranke_cran.asc
# apt-get update