The Suitability of RSA for Bulk Data Encryption

Symmetric ciphers are more efficient for bulk encryption than asymmetric ciphers, however there is a lack of published studies providing relevant metrics pertaining to bulk encryption with RSA in modern computing environments. As key escrow systems proposed against ransomware provide alternative routes for data restoration, ransomware developers will seek to deploy resistant cryptosystems. In this study, we examine the use of a popular asymmetric cipher (RSA) for bulk encryption. We provide metrics for both encryption time and ciphertext expansion while examining the impact of different encryption parameters such as key size and block size. In addition, we consider supplementing encryption with compression to combat both ciphertext expansion and encryption time. Our goal is to highlight the need for solutions against the ransomware that use externally generated asymmetric key pairs for bulk encryption.