Quantum Amplitude Hash Function for Quantum Evidence Integrity

The integrity of evidence, a core principle of digital forensics, is essential for ensuring the reliability and admissibility of evidence in legal proceedings. Classical cryptographic hash functions have effectively ensured the integrity of digital evidence. However, they cannot be applied to quantum evidence emerging with the advent of the quantum computing era. This is due to fundamental principles of quantum mechanics such as superposition and entanglement. To address the challenge of ensuring quantum evidence integrity, this paper introduces a quantum amplitude hash function as a new paradigm. The function operates by directly hashing the entire amplitude, which represents the totality of information within the quantum evidence state, into a hash qubit. The proposed function is implemented as a quantum circuit of constant depth, ensuring excellent scalability. It is theoretically proven to satisfy key cryptographic properties such as preimage resistance, collision resistance, and sensitivity. Moreover, simulation experiments were conducted to validate the generation of hash qubits for representative quantum algorithms. This work is expected to lay a crucial technical foundation for advancing the field of quantum forensics and preparing for future investigative environments.