Good policies, the mere presence of an id_<ciphername> key in .ssh means you can be identified between multiple ssh servers. I identified this in the OpenSSH so

Good policies, the mere presence of an id_<ciphername> key in .ssh means you can be identified between multiple ssh servers. I identified this in the OpenSSH source a while ago and posted it on reddit at one point, but few people understood. Glad someone made a practical attack out of it now. IP correlation may seem a more obvious attack, but such an attack could be used to identify for example, someone running a darknet operation or using VPNs for privacy or simply to tie an IP to a name using a public key service like in this example.