SaTC: CORE: Small: New Cryptographic Capabilities for a Quantum World

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

The emergence of quantum technologies opens up new avenues for the development of cryptographic capabilities that would otherwise have been impossible to achieve. For example, once an adversary gains access to a string of data, they may store arbitrarily many copies of this string and there is no way to verify that the string was truly deleted. Even if the string is a ciphertext encoding an underlying plaintext, an adversary can always keep that ciphertext around forever or distribute many copies of it to malicious entities. If security of the underlying encryption scheme breaks down in the future, or if the key is compromised, malicious entities may be able to recover the plaintext – and this may be unacceptable for highly sensitive data. On the other hand, unknown quantum states cannot be copied, and measurements on these states are inherently destructive and irreversible. This raises the exciting possibility of building cryptosystems with strong deletion and unclonability properties by encoding information into quantum states. This research project enables these capabilities by carefully combining mathematical hardness with security that arises from the properties of quantum information. The first research focus develops cryptosystems that support verifiable deletion of sensitive data – these include advanced encryption schemes, methods of outsourcing to untrusted servers, and distributed secure computation. These schemes allow untrusted devices and servers to prove that they deleted or erased private records forever – even after they already had access to, or computed on, encodings of these records. The second focus strengthens the quantum no-cloning principle in cryptographically useful ways, to build strong foundations for unclonable cryptography. This leads to cryptosystems that prevent an adversary from splitting a quantum encoding into two or more states that meaningfully encode an underlying secret. The project also establishes mentoring programs and seminars for cryptography researchers and develops expository material to benefit an upcoming generation of researchers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.