CS News:
Abhi Shelat Constructs Encryption Protocols
to Power Security Applications
In the field of computer security, even the safest encryption procedures are vulnerable to future advances in technology. The encryption schemes that undergird the exchange of sensitive information on the Internet, like medical records and financial transactions, are under constant assault from adversaries using more and more sophisticated means of attack. Assistant Professor Abhi Shelat is constructing new encryption protocols that will power the security applications needed to stay ahead of these coming vulnerabilities, especially those associated with the development of quantum computers.
Shelat’s work expounds on the fundamental theory of encryption, identifying the questions that must be answered to reveal the path forward in the successful construction of new encryption schemes. One such question is whether it’s possible to encrypt messages of varying lengths when cryptographic manipulation of the string is limited to a single bit. While this is viable within simple encryption schemes, the method had never been proven to hold up under chosen-ciphertext attack, a scenario in which an adversary submits a known ciphertext to the defended system in hopes of learning further information to solve a challenge message.
The issue of whether bit encryption could hold up under such an attack had remained unresolved within the field of cryptanalysis since 1991. Last year, working with a collaborator at the University of Indiana, Shelat resolved the 20-year-old problem, proving that encryption schemes reliant on weak cryptographic assumptions such as bit encryption may nevertheless be sophisticated enough to satisfy the prevailing security requirements for Internet transactions.
In other research, Shelat is exploring the potential of fully homomorphic encryption. “FHE allows an individual to add or multiply encrypted data with other encrypted data without having to decrypt the data first,” says Shelat. “This new form of encryption allows many great new applications while at the same time raising new questions.”