Erro de certificado ao usar o sudo apt-get update

Question

Eu tentei perguntar isso no askubuntu mas não encontrei uma resposta .

Eu instalei o Ubuntu Server 32-bit 14.04 em uma máquina antiga, e tentei executar sudo apt-get update mas é seguido por essa mensagem de erro:

Ign http://security.ubuntu.com trusty-security InRelease 
Ign http://security.ubuntu.com trusty-security Release.gpg 
Ign http://security.ubuntu.com trusty-security Release 
Err http://security.ubuntu.com trusty-security/main Sources    
Err http://security.ubuntu.com trusty-security/main Sources    
Err http://security.ubuntu.com trusty-security/main Sources    
Err http://security.ubuntu.com trusty-security/main Sources    
Err http://security.ubuntu.com trusty-security/main Sources 
    server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none 
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/trusty-security/main/source/Sources server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none

E: Some index files failed to download. They have been ignored, or old ones used instead.

Eu tentei as seguintes soluções:

1. Atualize o servidor de DNS para 8.8.8.8 e 8.8.4.4

2. sudo update-ca-certificates

    Updating certificates in /etc/ssl/certs... 0 added, 0 removed; done.
    Running hooks in /etc/ca-certificates/update.d....
    done.
    done.
   

3. Certifiquei-me de que não está sendo feito em conexão proxy.

sources.list

# 

# deb cdrom:[Ubuntu-Server 14.04.3 LTS _Trusty Tahr_ - Beta i386 (20150805)]/ trusty main restricted

#deb cdrom:[Ubuntu-Server 14.04.3 LTS _Trusty Tahr_ - Beta i386 (20150805)]/ trusty main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ trusty main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ trusty universe
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty universe
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ trusty multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://us.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu trusty-security main restricted
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner

## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu trusty main
# deb-src http://extras.ubuntu.com/ubuntu trusty main