If this is run within a VPS, you must also trust the VPS provider and the supervisor OS not to have backdoors/faults like Xen and others had discovered recently.

If your attacker can become root on your VPS, they can also "simply" extract the key by reading the memory of your process:

open my $process, '<', "/proc/$apache/mem";
binmode $process;
binmode STDOUT;
print $_ while <$process>;

[download]

But unless you can store the key on a hardened USB encryption/decryption device and perform decryption on that device, having the key only in memory reduces the attack surface a lot. Your attacker has to attack the live machine(s) instead of for example attacking a backup tape.

In reply to Re^3: Effective database column level encryption? by Corion
in thread Effective database column level encryption? by maruhige

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