我正在尝试在 Debian 7 32 位机器上安装 PHP4，但遇到了以下问题
root@php4:~# apt-get update
Get:1 http://snapshot.debian.org lenny Release.gpg [189 B]
Hit http://snapshot.debian.org lenny Release
Ign http://snapshot.debian.org lenny Release
Hit http://snapshot.debian.org lenny/main Sources/DiffIndex
Hit http://snapshot.debian.org lenny/main i386 Packages/DiffIndex
Hit http://ftp.us.debian.org wheezy Release.gpg
Hit http://security.debian.org wheezy/updates Release.gpg
Ign http://snapshot.debian.org lenny/main Translation-en_US
Ign http://snapshot.debian.org lenny/main Translation-en
Hit http://ftp.us.debian.org wheezy Release
Hit http://security.debian.org wheezy/updates Release
Hit http://ftp.us.debian.org wheezy/main i386 Packages
Hit http://ftp.us.debian.org wheezy/main Translation-en
Hit http://security.debian.org wheezy/updates/main i386 Packages
Hit http://security.debian.org wheezy/updates/main Translation-en
Fetched 189 B in 0s (229 B/s)
Reading package lists... Done
W: GPG error: http://snapshot.debian.org lenny Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A70DAF536070D3A1
我做了以下来解决这个问题
gpg --keyserver hkp://subkeys.pgp.net --recv-keys A70DAF536070D3A1
gpg --export --armor A70DAF536070D3A1 | sudo apt-key add -
现在我收到以下 KEYEXPIRED 错误，不知道如何修复。甚至谷歌也帮不上忙
root@php4:~# apt-get update
Get:1 http://snapshot.debian.org lenny Release.gpg [189 B]
Hit http://snapshot.debian.org lenny Release
Ign http://snapshot.debian.org lenny Release
Hit http://snapshot.debian.org lenny/main Sources/DiffIndex
Hit http://security.debian.org wheezy/updates Release.gpg
Hit http://snapshot.debian.org lenny/main i386 Packages/DiffIndex
Hit http://ftp.us.debian.org wheezy Release.gpg
Hit http://security.debian.org wheezy/updates Release
Ign http://snapshot.debian.org lenny/main Translation-en_US
Hit http://ftp.us.debian.org wheezy Release
Hit http://security.debian.org wheezy/updates/main i386 Packages
Ign http://snapshot.debian.org lenny/main Translation-en
Hit http://ftp.us.debian.org wheezy/main i386 Packages
Hit http://security.debian.org wheezy/updates/main Translation-en
Hit http://ftp.us.debian.org wheezy/main Translation-en
Fetched 189 B in 0s (275 B/s)
Reading package lists... Done
W: GPG error: http://snapshot.debian.org lenny Release: The following signatures were invalid: KEYEXPIRED 1246455239
有什么帮助吗？