3 research outputs found
On the Duality of Probing and Fault Attacks
In this work we investigate the problem of simultaneous privacy and integrity
protection in cryptographic circuits. We consider a white-box scenario with a
powerful, yet limited attacker. A concise metric for the level of probing and
fault security is introduced, which is directly related to the capabilities of
a realistic attacker. In order to investigate the interrelation of probing and
fault security we introduce a common mathematical framework based on the
formalism of information and coding theory. The framework unifies the known
linear masking schemes. We proof a central theorem about the properties of
linear codes which leads to optimal secret sharing schemes. These schemes
provide the lower bound for the number of masks needed to counteract an
attacker with a given strength. The new formalism reveals an intriguing duality
principle between the problems of probing and fault security, and provides a
unified view on privacy and integrity protection using error detecting codes.
Finally, we introduce a new class of linear tamper-resistant codes. These are
eligible to preserve security against an attacker mounting simultaneous probing
and fault attacks
Formal Computational Unlinkability Proofs of RFID Protocols
We set up a framework for the formal proofs of RFID protocols in the
computational model. We rely on the so-called computationally complete symbolic
attacker model. Our contributions are: i) To design (and prove sound) axioms
reflecting the properties of hash functions (Collision-Resistance, PRF); ii) To
formalize computational unlinkability in the model; iii) To illustrate the
method, providing the first formal proofs of unlinkability of RFID protocols,
in the computational model
Fully Invisible Protean Signatures Schemes
Protean Signatures (PS), recently introduced by Krenn et al. (CANS \u2718), allow a semi-trusted third party, named the sanitizer, to modify a signed message in a controlled way.
The sanitizer can
edit signer-chosen parts to arbitrary bitstrings, while the sanitizer can also redact
admissible parts, which are also chosen by the signer. Thus, PSs generalize both redactable signature (RSS) and sanitizable signature (SSS)
into a single notion.
However, the current definition of invisibility does not prohibit that an outsider can decide which
parts of a message are redactable - only which parts can be edited are hidden. This negatively
impacts on the privacy guarantees provided by the state-of-the-art definition.
We extend PSs to be fully invisible.
This strengthened notion guarantees that an outsider can neither decide which parts of a message can be edited nor which
parts can be redacted. To achieve our goal, we introduce the new notions of Invisible RSSs and Invisible Non-Accountable SSSs (SSS\u27), along with a consolidated framework for aggregate signatures.
Using those building blocks, our resulting construction is significantly
more efficient than the original scheme by Krenn et al., which we demonstrate in a prototypical implementation