Cryptovirology

Cryptovirology is a field that studies how to use cryptography to design powerful malicious software. The field was born with the observation that public-key cryptography can be used to break the symmetry between what a malware analyst sees regarding malware and what the malware creator sees. The former sees a public key in the malware whereas the latter sees the public key as well as the corresponding private key since the malware designer created the key pair for the attack. The public key allows the malware to perform trapdoor one-way operations on the victim's computer that only the malware creator can undo.