Cryptolocker (Ransomware)
Asymmetric encryption is part of the issue where a public key is used to encrypt, but a private key is needed to decrypt. It can go in reverse order, however, that former is usually the standard.
The math itself is based upon parametric equations from calculus (not to be confused with parametric statistics using a normal (Guassian curve) distribution.
My Malwarebytes has detected and deleted both back door Trojans and Trojan.Ransom. My VIPRE firewall has kept many would be attacks from even getting near my files or hard drive.
RSA, DSA and PGP are three forms of asymmetric encryption. I have a certificate in Cryptography and I have worked with some very strange malware types.