Abstract
Key distribution is an important cryptographic primitive, which is needed by more complex cryptographic tasks such as authentication and data encryption. Without key distribution, online banking would no longer be secure, anyone could read anyone’s emails and critical infrastructure such as the electrical grid would be open to interference by malicious parties. Conventionally, public key cryptography has been used, however, commonly used algorithms such as RSA are vulnerable to attacks by future quantum computers.Quantum key distribution (QKD) offers an alternative, promising security through security proofs that not even the most advanced, theoretically possible computer could break. However, even with security proofs, QKD only offers perfect security with devices perfectly meeting any assumptions made in the security proof. Therefore, the implementation of a QKD system must be tested and monitored to ensure the devices operate as expected.
One trend in QKD research nowadays is the push to miniaturise the systems by using integrated photonic chips, which take up less space, cost less when produced at high volume and offer excellent optical stability. However, very little work has been done to investigate implementation security of chip-scale QKD, so far. In this thesis, the implementation security of chip-scale QKD transmitters is explored, first concentrating on two attacks, the Trojan Horse attack (THA) and the laser damage attack (LDA), that have previously been demonstrated on fibre-optic and bulk-optic QKD systems.
Next, using the results from the attack research, a new high-speed transmitter chip design for measurement device independent (MDI) QKD was designed, including a hacking prevention mechanism circuit. This new chip would allow symbol rates of up to 7.7 GHz for a time-bin encoded scheme. Due to the intrinsic security of MDI QKD against detector attacks, the new design also offers excellent overall implementation security.
| Date of Award | 2 Feb 2023 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | John G Rarity (Supervisor), Christopher Erven (Supervisor) & Djeylan V C Aktas (Supervisor) |