For other confused readers, RSA with 512 bits uses 155 decimal digits. Hence RSA-155. This seems to be old notation from the RSA challenge that was clasiffied b

For other confused readers, RSA with 512 bits uses 155 decimal digits. Hence RSA-155. This seems to be old notation from the RSA challenge that was clasiffied by the decimal length of numbers rather than the bit-length. Note that RSA-155bit is much worse than RSA-512bit. Both are insecure and should not be used, but you are still looking at the difference of "you need to rent a server farm to crack is" and "you need a laptop to crash it". I'm probably underselling how trivial RSA-155 is to crack.