Dissertation Defense: Manasi Shingane

Title:  Quantum Cryptography in the Presence of Side Information
Speaker:  Manasi Shingane (QuICS)
Date & Time:  June 12, 2026, 9:30am
Where to Attend:  ATL 3100A and Virtual Via Zoom: https://umd.zoom.us/j/4408046564?pwd=jxxFPSb0TCV3qYiZv6WbLncFIvVyPX.1    Password:  628758 

Quantum cryptography establishes the security of cryptographic protocols in the presence of quantum adversaries. However, at times, the theoretical security models we consider rely on highly idealized environments. In many realistic settings, adversaries may  possess different forms of ``side information", such as physical leakage describes the information about secrets, pre-shared entanglement, or correlated advice strings. This thesis formally investigates the feasibility, security, and theoretical limits of various quantum cryptographic protocols in which adversaries are augmented with different types of side information.

In the first part of the thesis, we explore the limits of efficient verification protocols with low communication complexity in the presence of auxilliary information. We establish new impossibility results for specific cryptographic primitives used for verification known as Succinct Non-interactive Arguments (SNARGs) with quantum security guarantees. We demonstrate that granting adversaries additional quantum capabilities does not allow one to circumvent known classical impossibility results.
 
In the second part of the thesis, we explore side information in the form of adversarial key leakage i.e, obtaining information directly correlated with the secret key of a scheme. By adapting classical leakage-resilient frameworks to the quantum domain, we provide two public key encryption (PKE) schemes that satisfy varying leakage resilience guarantees. The first PKE scheme is constructed with a quantum secret key and is secure under unbounded classical leakage resilience and constant rate quantum leakage. The second PKE scheme is constructed with a classical secret key, and is secure under bounded quantum leakage, which may include any classical leakage correlated with the secret key. The second PKE scheme satisfies an optimal leakage rate that scales arbitrarily close to $1$.

In the third part of the thesis, we explore how non-local games and quantum position verification (QPV) can be used to construct a protocol that verifies the existence of entanglement between two particular locations. Then, we investigate how pre-shared entanglement among colluding adversaries impacts protocol security. Specifically, we explore how entanglement, as a particular type of quantum side information, allows adversaries to spoof guarantees related to their spatial location.

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