1st Workshop on Generic Attacks and Proofs in Symmetric Cryptography
Generic Attacks and Proofs in Symmetric Cryptography (GAPS 2025) is a research workshop at NTU Singapore (September 1–5, 2025) bringing leading and early-career cryptographers together from the area of provable symmetric-key cryptography. Framed by the theme “Five Decades of Provable Security of Symmetric Ciphers: Challenges and Future Developments,” it featured invited talks and discussions on bridging proofs and attacks, foundational techniques, new notions for real-world threats, (post-)quantum security proof techniques, leakage resilience, and automated proof verification, among others.
Prof. Elena Andreeva gave a talk titled “Expanding the Scope, Security, and Efficiency of Classical Symmetric Primitives,” highlighting how expanding symmetric-key primitives — such as the ForkSkinny forkcipher and the Butterknife tweakable pseudorandom function — offer stronger security and higher efficiency than classical block ciphers and recent tweakable cipher symmetric primitives. She showed that across multiple application scenarios — including, authenticated encryption (SAFE, r/PAEF, ZAFE), key-derivation functions (Skye) for protocols such as Signal, encryption for resource-constrained IoT devices and decryption in cloud environments (Eevee), and message authentication (Sonniku) — expanding primitives can surpass traditional security bounds (e.g., the birthday bound). They also provide robustness properties such as nonce-reuse resilience, resistance to release of unverified plaintext, and block-wise adaptive security. Another important feature is that expanding primitives offer significant performance improvements over classical symmetric-key algorithms (e.g., AES) and more recent tweakable block ciphers.
Prof. Andreeva concluded by emphasizing the inherent flexibility of expanding symmetric-key primitives and proposed several avenues for future research aligned with the workshop’s goals.
Supplementary References:
- Andreeva, E., Bhati, A. S., Preneel, B., & Vizár, D. (2021). 1, 2, 3, Fork: Counter Mode Variants based on a Generalized Forkcipher
- Bhati, A. S., Dufka, A., Andreeva, E., Roy, A., & Preneel, B. (2024). An Expanding PRF based Fast KDF and its Applications