In 2008, it was discovered that a patch in Debian's and Ubuntu's OpenSSL package caused the random number generator to malfunction. Effectively, this meant that the process id (PID) was the only source of randomness.
This allows calculating all possible private keys generated by this vulnerable OpenSSL package. However, variations due to the tool used (OpenSSL directly vs. OpenSSH), the architecture, and the presence of certain config files still create many variations. Due to these variations, existing tools and lists are often incomplete.
We check standard key sizes (1024, 2048, 3072, 4096) created on 32 and 64 bit x86 architectures, as well as ppc, with both OpenSSL and OpenSSH. We also check ECDSA keys with the NIST P256 and P384 curves.