6 papers
Security of the Fischlin Transform in Quantum Random Oracle Model
Christian Majenz, Jaya Sharma
The Fischlin transform yields non-interactive zero-knowledge proofs with straight-line extractability in the classical random oracle model. This is done by forcing a prover to gene…
Post-Quantum Security of Block Cipher Constructions
Gorjan Alagic, Chen Bai, Christian Majenz +1
Block ciphers are versatile cryptographic ingredients that are used in a wide range of applications ranging from secure Internet communications to disk encryption. While post-quant…
Quantum Oracle Distribution Switching and Applications to Falcon and Ring Signatures
Marvin Beckmann, Christian Majenz
Motivated by digital signature algorithms ranging from Falcon to fully-anonymous ring signatures used in Signal-style key exchange, such as Gandalf, we revisit a fundamental proble…
The Sponge is Quantum Indifferentiable
Gorjan Alagic, Joseph Carolan, Christian Majenz +1
The sponge is a cryptographic construction that turns a public permutation into a hash function. When instantiated with the Keccak permutation, the sponge forms the NIST SHA-3 stan…
Quantum copy-protection of compute-and-compare programs in the quantum random oracle model
Andrea Coladangelo, Christian Majenz, Alexander Poremba
Copy-protection allows a software distributor to encode a program in such a way that it can be evaluated on any input, yet it cannot be "pirated" - a notion that is impossible to a…
Permutation Superposition Oracles for Quantum Query Lower Bounds
Christian Majenz, Giulio Malavolta, Michael Walter
We propose a generalization of Zhandry's compressed oracle method to random permutations, where an algorithm can query both the permutation and its inverse. We show how to use the…