35 results for “cipher”

Poly2MsgLeaks is a profiled chosen-ciphertext power-analysis attack on the SMAUG-T (TiMER parameter set) post-quantum KEM that recovers the full 512-coefficient PKE secret from six traces on an STM32F415. It recovers 999 of 1,000 unseen secrets and proves an incorrect key is released with probability at most 2^-2095.6. Single-write message assembly and a two-share masked P2M resisted the evaluated six-execution attack.

eprint.iacr.orgpaperAdded 28 Oct 2026, published 27 Oct 2026🛡️ Security

ZMAC+ is a tweakable-block-cipher MAC (List and Nandi, ToSC 2017) with claimed beyond-birthday-bound security. This ePrint paper (2026/2647) shows a tag-swap attack: for two-block tags, a distinguisher and a fresh-message forgery with constant success probability using O(2^{n/2}) queries in the ideal-TBC model. It also corrects a counting error in the published Lemma 4 and proposes a repaired variant with an adaptive PRF bound of order q^2/2^{n+min(n,t)}.

eprint.iacr.orgpaperPublished and added 26 Oct 2026🛡️ Security

Provable Security of SHA-256-Based LMS Revisited in the Ideal-Cipher Model is an October 2026 ePrint paper by Chun Guo, Hao Cheng, Bart Preneel and Meiqin Wang. It shows forgery attacks on LMS_SHA256_M32 and LMS_SHA256_M24 that exploit Merkle-Damgård structure, so the Katz and Fluhrer random-oracle bounds do not apply. It proves ideal-cipher-model bounds: about 256 minus log2 of the block count for M32, and a minimum of two terms for M24.

eprint.iacr.orgpaperAdded 26 Oct 2026, published 24 Oct 2026🛡️ Security

Rentaro Shiba and Tetsu Iwata prove a tight multi-key security bound for the FX construction (the DESX generalization) in the quantum ideal cipher model. Security holds up to about 2^((n+κ)/3) total classical and quantum oracle queries against fully adaptive adversaries, for any number of keyed instances μ≥1. This improves their ToSC 2026 bound and matches the offline Simon's algorithm attack in the exponent.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 23 Oct 2026🛡️ Security

Mímir is a cryptographic protocol for stateless semantic private search over highly dynamic public databases. It uses homomorphic ciphertext switching, relies on (Ring) Learning with Errors, and needs no offline communication. Against Tiptoe it matches search quality with 84x less per-query communication (0.24 MiB). Against PACMANN it raises quality from 76% to 81% of non-private search, with a 9.54 MiB one-time cost instead of 2.68 GiB, but is 2.1x slower.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 22 Oct 2026🛡️ Security

Linear cryptanalysis of FRAST, a TFHE-friendly stream cipher, in the average key setting. It fixes the false-positive problem left open in the earlier attack by Bak et al., showing key differences fall into five indistinguishable classes per round. The Contract algorithm recovers the master key for 10 rounds and, on weak keys of density 2^-11.8 to 2^-5.4, reaches full FRAST within the claimed security.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 22 Oct 2026🛡️ Security

This ePrint paper gives the first exact bit-level models of modular multiplication z=(x·y) mod 2^n. One model is for monomial prediction under 3SDP-woU, the other for impossible differential search. Applied to the MSX lightweight cipher, it yields a 7-round integral distinguisher (2^96 data) for MSX-128, key recoveries on 8 and 9 of 18 rounds at about 2^228 operations, and 1,984 seven-round impossible differentials. Both models are implemented in CLAASP.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 21 Oct 2026🛡️ Security

SoK on design-level backdoors in block ciphers. It places four published designs (Rijmen and Preneel, Paterson, Bannier and Filiol, Peyrin and Wang) in one taxonomy and gives a sound algorithm that recovers a partition trapdoor from S-box tables. It attacks KG-DES, BEA-1 and LowMC-M: KG-DES key recovery takes minutes, and the LowMC-M MALICIOUS backdoor yields the key from 35 to 409 queries. Trapdoors hidden in linear layers leave no trace, so the authors recommend deriving constants verifiably from a public seed.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 21 Oct 2026🛡️ Security

Broadcast and Trace from Lattices is a 2026 ePrint preprint by Jeffrey Champion. It builds collusion-resistant broadcast and trace with public tracing from attribute-based encryption with succinct ciphertexts and lockable obfuscation, both known from decomposed LWE. Ciphertexts are sqrt(N)·poly(λ, log N) in size, with poly(λ, log N) keys. It is the first such scheme based on a simple, instance-independent lattice assumption.

eprint.iacr.orgpaperAdded 24 Oct 2026, published 21 Oct 2026🛡️ Security

Registered ABE via Predicate Encodings, Revisited is an ePrint paper by Junichi Tomida (October 2026) that gives a new definition of predicate encodings suited to registered attribute-based encryption. It yields the first Reg-ABE schemes for (non-)zero inner product and for conjunctions/disjunctions with O(log L)-size ciphertexts. It also gives a registered broadcast encryption scheme with O(log L)-size ciphertexts under the standard k-Lin assumption, not the generic group model.

eprint.iacr.orgpaperAdded 20 Oct 2026, published 19 Oct 2026🛡️ Security

Blind-DLPA is a multi-task deep-learning framework for profiled blind side-channel analysis, where the attacker has labeled profiling traces but only leakage traces from the target, with no plaintexts or ciphertexts. It estimates Hamming-weight posteriors of an input and a key-dependent intermediate, then ranks key hypotheses against theoretical joint distributions. It recovers keys on unprotected AES and Kyber and on ASCAD (guessing entropy zero with 39 traces), and the authors report collisions in a prior Ascon Hamming-weight model.

eprint.iacr.orgpaperAdded 20 Oct 2026, published 19 Oct 2026🛡️ Security

IISFA (Ineffective Instruction-Skip Fault Attack) targets bitsliced block cipher implementations protected by redundancy countermeasures. Skipping one bitslice instruction leaves the result unchanged only when all m S-box inputs fall in an ineffective set, so each released ciphertext restricts all m subkeys. The authors give known- and chosen-plaintext key-recovery procedures and expected injection counts, and recover keys in every trial on GIFT, SKINNY and PIPO implementations on an 8-bit AVR microcontroller using clock glitches.

eprint.iacr.orgpaperAdded 20 Oct 2026, published 19 Oct 2026🛡️ Security

Forum announcement of a Zenodo preprint on post-quantum migration for censorship-resistant P2P steganographic tunnels. It argues that ML-KEM's prime modulus (q=3329) makes naive bit-packed ciphertexts statistically distinguishable from uniform noise, which gives a cheap passive DPI distinguisher. It also argues that composite PQ 0-RTT envelopes over 4.4 KB force fragmentation, which requires stateful reassembly before AEAD verification and reopens memory-exhaustion DoS in eBPF/XDP filters. Proposed fixes are algebraic uniformization (LWR lattices or inverse rejection sampling), sub-MTU hybrid or pure-PQ envelopes (Falcon-512, signcryption), and Fujisaki–Okamoto implicit rejection for constant-time silent drops. Aimed at Ethereum validator, libp2p and RPC transports facing harvest-now-decrypt-later threats.

ethereum-magicians.orgpaperPublished and added 17 Oct 2026🛡️ Security

Cryptanalysis of the Eevee forkcipher-based AEAD modes Umbreon and Espeon, which claim online AE security under nonce reuse. Associated-data correlations give probability-one non-empty-message forgeries with three encryption queries and one verification query. The paper adds an affine treatment of partial final blocks (n-r+3 queries, or n-r+2 with adaptive choices). It also checks the published Umbreon attack with the official ForkSkinny primitive and reports a two-query attack accepted by the unmodified public C modes.

eprint.iacr.orgpaperPublished and added 17 Oct 2026🛡️ Security

Introduces SLEEK, a QC-MDPC code-based KEM using a three-iteration parallel bit-flipping decoder and a closed-form decoding-failure-rate (DFR) estimate, enabling parameters with analytically bounded failure probability and standard IND-CCA transforms. SLEEK-LT targets IND-CCA for long-term keys; SLEEK-E targets IND-CPA for ephemeral keys using a new QC key structure with security equivalent to QC-MDPC and cheaper key generation. Parameter sets cover 80/128/192/256-bit security, and the optimized AVX2 implementation gives ciphertexts 4.9x smaller than HQC (47% slower) and 1.3x–2.7x faster than BIKE.

eprint.iacr.orgpaperAdded 17 Oct 2026, published 16 Oct 2026🛡️ Security

ePrint paper presenting the first optimized implementation of the BF-max bit-flipping decoder for the code-based KEM BIKE, combined with other decoders to trade off decoding failure rate, runtime, public-key and ciphertext size in ephemeral-key settings. It cuts public-key and ciphertext sizes by 7.8% versus LeanBIKE at similar speed and DFR, and gives a combined size 22% below BIKE and 2.79x below HQC. It shows BIKE can fit constrained protocols such as IKEv2, which matters for practical post-quantum migration.

eprint.iacr.orgpaperAdded 17 Oct 2026, published 16 Oct 2026🛡️ Security

ePrint paper cryptanalysing Eevee (Umbreon, Jolteon, Espeon), forkcipher-based AEAD modes proposed at CCS 2023 for IoT-to-cloud computation. It gives a two-encryption AD-free prefix distinguisher, a four-encryption nonce-misuse distinguisher, a deterministic AD-only forgery, and nonce-respecting forgeries on Jolteon and Espeon (fresh one-block forgery reusing the tag; arbitrary AD substitution). It traces these to proof flaws (online-prefix consistency, domain separation, checksum freshness), derives design requirements, and concludes the failures are in the mode design, not the C implementation.

eprint.iacr.orgpaperPublished and added 15 Oct 2026🛡️ Security

T-EVOLVE extends the lattice-commitment e-voting protocol EVOLVE to threshold tallying. Votes are Shamir-shared, so any t of n authorities can finish the tally. Privacy holds against t-1 colluding authorities and verifiability holds even if all of them collude. The voter proves her committed shares form a Reed-Solomon codeword whose value at zero is a valid vote. Complaints about ciphertexts that do not decrypt are publicly verifiable, using an LWE-instantiable encryption scheme with publicly verifiable opening. Privacy, verifiability, individual verifiability and robustness are proven in the classical random oracle model, and the verifiability reduction is not tight. In a C implementation, a yes/no ballot for four authorities takes 109 KB, and an authority aggregates 10^4 ballots in about three minutes on one core.

eprint.iacr.orgpaperAdded 17 Oct 2026, published 15 Oct 2026🛡️ Security

Presents fault injection attacks on BIKE and HQC decapsulation that target instructions outside the Fujisaki-Okamoto transform, achieving full key recovery with only valid ciphertexts at NIST Level 1 (17392 queries for HQC, about 3 million for BIKE). It also gives a general method for finding effective fault locations by analysing decoder behaviour under perturbed conditions. Attacks were validated with laser fault injection on an STM32H7 microcontroller, showing a wider attack surface for code-based post-quantum KEM implementations.

eprint.iacr.orgpaperPublished and added 15 Oct 2026🛡️ Security

Shows a protocol-level reaction attack on CKKS homomorphic-encryption deployments that publish coefficient-to-slot (C2S) evaluation keys and let the client return a 1-bit validity response. A malicious evaluator shifts a public encryption key, uses the public C2S layer to repack it into a ciphertext whose validity depends on one secret coefficient, and recovers a ternary secret key with O(H) queries, within a factor 2/log2(3) of the entropy lower bound. Each query is re-randomized with a fresh encryption of zero to evade trivial detection. The authors implemented it end to end in Lattigo v6.2.0 and recovered full keys across four standard CKKS parameter sets. It does not break RLWE or CKKS IND-CPA security.

eprint.iacr.orgpaperPublished and added 15 Oct 2026🛡️ Security

Proposes a cost model and metric for an adversary who collects side-channel traces classically and finishes the key search on a quantum computer. Shows any quantum algorithm needs Omega(sqrt(r)) cipher evaluations for key rank r, and that the quadratic advantage holds only up to a rank bound set by the NIST MAXDEPTH budget (about 2^58.6 for AES-128 at D=2^40). Defines a quantum-aware key rank computable from existing rank estimators, with simulated-leakage experiments showing a depth-limited quantum adversary is worth about 22 traces at SNR 0.125.

arxiv.orgpaperAdded 16 Oct 2026, published 14 Oct 2026🛡️ Security

Introduces leakage-resilient incompressible cryptography, a security model combining leakage resilience (partial key leakage plus full ciphertext) with incompressibility (full key but only part of the ciphertext or signature). It gives a transformation from incompressible symmetric-key encryption (SKE) to leakage-resilient incompressible SKE, a leakage-resilient incompressible PKE built from a new leakage-resilient non-committing KEM, and an incompressible SKE with ciphertext and compression rate 1/2 using invertible extractors. It also gives a leakage-resilient incompressible signature scheme in the random oracle model under DCR or LWE plus Decisional Linear. Black-box impossibility results show barriers to improving these parameters.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 13 Oct 2026🛡️ Security

The paper builds explicit ReLU neural-network realizations of Camellia-128/192/256 from exact Boolean gates, S-box selectors and bit permutations, and reports known-answer-test agreement for Camellia-128. It shows that whitening and round-key quantities leaked from internal activations determine the master key through public key-schedule identities. Under a synthetic internal-oracle model, symmetric real-valued perturbations recover subkey bits with 128 queries (Camellia-128) or 256 (Camellia-256). Camellia-192 is handled by deterministic key-schedule inversion from direct access to round keys. All 3,000 trials (1,000 keys per variant) recovered the key exactly. The authors state this is not a plaintext/ciphertext-only attack on standard Camellia.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 13 Oct 2026🛡️ Security

ePrint paper presenting share-optimal, direct, uniform, first-order threshold implementations (TIs) with no fresh randomness. It shows every bijective 4-bit permutation of algebraic degree t admits a TI with t+1 shares, and introduces the first infinite families of cryptographically nontrivial power permutations with optimal TIs. The results disprove several earlier conjectures and give new glitch-resistant masking options for lightweight cipher S-boxes.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 12 Oct 2026🛡️ Security

Preprint recovering the long-term key of a first-order masked Kyber768 implementation on an ARM Cortex-M4 from about 2200 decapsulation power traces using only valid ciphertexts. A profiled neural network estimates Hamming-weight distributions of both arithmetic shares, which are turned into likelihoods on decryption noise and combined by a belief-propagation solver with Gaussian interference approximation and an Onsager (AMP) correction, recovering all 1536 secret and error coefficients without lattice reduction. It shows first-order masking is insufficient against combined second-order leakage, and that least squares, greedy solvers and lattice hints (BKZ block size 624 to 505 at 2000 traces) do worse.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 12 Oct 2026🛡️ Security

Mori and Emura give a generic transformation, a variant of the CHK transformation, that upgrades a public-key authenticated encryption with keyword search (PAEKS) scheme to one secure against chosen-ciphertext and trapdoor attacks (CCTA). It works because the PAEKS receiver names the sender when generating a trapdoor, so keywords can serve as tags. Applied to Li-Boyen generic PAEKS instantiations, it yields the first fully CCTA-secure PAEKS schemes from pairings and from lattices. Verification keys embedded in ciphertexts and trapdoors also let sender-receiver matching use hash tables, so search cost no longer depends on the number of senders.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 11 Oct 2026🛡️ Security

The paper proposes a generic encrypt-then-MAC transformation for building CCA-secure KEMs. The PKE ciphertext is authenticated by a MAC keyed from the PKE plaintext, so decapsulation no longer needs the Fujisaki-Okamoto re-encryption step. It proves IND-CCA security in the random oracle model from OW-PCA, and IND-qCCA security from a new OW-qPCA notion. It presents ML-KEM-EtM and McElieceEtM (Classic McEliece), and benchmarks ML-KEM-EtM with Poly1305, GMAC, CMAC and KMAC256. The result is a substantially lower decapsulation cycle count for a small cost in encapsulation cycles and ciphertext size.

eprint.iacr.orgpaperAdded 14 Oct 2026, published 11 Oct 2026🛡️ Security

Proves that the nonce-based MACs Encrypted Wegman-Carter (EWC) and EWCDMD (the dual of EWCDM) are unforgeable beyond the birthday bound. With an n-bit block cipher and an O(2^-n)-AXU hash, both are secure up to 2^{5n/6} MAC queries and nearly 2^n verification queries in the nonce-respecting setting. This settles an open question left by earlier birthday distinguishing attacks (Cogliati–Seurin on EWC, Nandi on EWCDMD), which never yielded forgeries. The proofs analyze forgery events directly through auxiliary experiments. The EWC proof adds conditional permutation analysis and collision multiplicity bounds with KL divergence, and the EWCDMD proof uses Hellinger distance and Fourier analysis.

eprint.iacr.orgpaperAdded 12 Oct 2026, published 9 Oct 2026🛡️ Security

KIFA is an integral fault attack framework that finds balanced properties with the kernel-based miner of Hwang et al. instead of MILP. It gives key-recovery attacks at deeper fault penetration than earlier work. On DEFAULT it reaches FP 9 with a nibble fault and FP 10 with a byte fault, leaving a single master-key candidate under the simple key schedule and 2^64 under the rotating one. It gives the first integral fault attacks on GIFT-128 (FP 7 and 8), extends GIFT-64 to FP 7, and extends BAKSHEESH to FP 8, including with an uncontrolled fault position.

eprint.iacr.orgpaperAdded 11 Oct 2026, published 8 Oct 2026🛡️ Security

This IACR eprint paper studies how to allocate a fixed global logical-qubit budget across parallel Grover search workers attacking 80-round and revised 112-round CHAM-128/128, choosing which intermediate round values to retain to minimize circuit depth while meeting a target key-recovery success probability. Testing 83- and 99-set retention libraries against a no-retention/full-retention baseline across 654 budget and Toffoli-decomposition conditions, the authors report mean depth reductions of 11.12% and 8.39% with strict improvements in most conditions, and show retained-value counts don't necessarily scale with budget. The work gives concrete logical-layer resource estimates for quantum attacks on CHAM, relevant to post-quantum migration planning for the lightweight cipher in constrained systems.

eprint.iacr.orgpaperAdded 8 Oct 2026, published 7 Oct 2026🛡️ Security

An IACR ePrint preprint applying differential-neural cryptanalysis to the ARX stream cipher family (ChaCha, Salsa, Forró), training six neural architectures (Gohr's residual network, DBitNet, an Inception network, MLP-ResNet, SE-ResNet, a self-attention network) in single-pair and multi-pair settings. It reports new distinguishers — 3-round ChaCha, 4.5-round Salsa, 1.25-round Forró — and uses explainability analysis to show the 3-round ChaCha distinguisher learns a mixture of round-1 truncated differentials rather than a pure differential signal.

eprint.iacr.orgpaperAdded 8 Oct 2026, published 6 Oct 2026🛡️ Security

An IACR eprint paper proving four of five open conjectures, and disproving the fifth with a counterexample, from Andreoli and colleagues at ToSC 2025 about the linear height and component linear nullity of the inverse of ChiChi, the low latency nonlinear core used in the ChiLow cipher from Eurocrypt 2025 by Belkheyar and colleagues. The authors settle these bounds for all admissible branch lengths of the SWAP and 4-cycle generalizations, derive design consequences for ChiLow, and correct an erroneous data value from the prior work.

eprint.iacr.orgpaperAdded 8 Oct 2026, published 6 Oct 2026🛡️ Security

An IACR ePrint paper presenting K-LMS, an experimental variant of the NIST-standardized LMS hash-based post-quantum signature scheme in which the underlying hash is swapped for Korean primitives: the LSH-256 hash function (reference and vectorized) and a Tandem-DM double-block-length construction built from the CHAM, LEA, and ARIA block ciphers. The authors implement a non-invasive backend-swapping bridge over the reference LMS code and benchmark keygen/sign/verify latency, key/signature sizes, memory, and parameter sweeps, finding that hash substitution doesn't change key/signature sizes but that two measurement pitfalls (hash dispatch overhead, and software vs. hardware-accelerated SHA-256 baselines) can shift performance comparisons by an order of magnitude or 6x respectively. They report LSH-256 K-LMS signing on par with SHA-256 LMS in software, and 3.3-3.9x faster than a prior K-XMSS implementation because LMS needs fewer hash calls per Winternitz step than XMSS.

eprint.iacr.orgpaperAdded 8 Oct 2026, published 6 Oct 2026🛡️ Security

This IACR ePrint paper benchmarks 20 open-source Gröbner basis implementations against the proprietary Magma system on polynomial systems derived from small-scale AES over GF(2), using Easy/Medium/Hard difficulty tiers with ten instances each. In the Hard setting, msolve and Singular's slimgb completed all runs successfully with mean runtimes of 164s and 269s and peak memory of 3693/4343 MiB respectively, versus Magma's 319s and 16853 MiB, with msolve exploiting ~13.4 CPU cores versus ~1 core for the others. The results quantify when open-source algebraic solvers are practical alternatives to Magma for algebraic cryptanalysis of block ciphers.

eprint.iacr.orgpaperAdded 8 Oct 2026, published 5 Oct 2026🛡️ Security

This paper tightens the soundness bound of the compressed permutation oracle technique (a proof tool for analyzing quantum adversaries against random-permutation/ideal-cipher-based constructions) from O(N^1/12) queries to a tight Ω(N^1/2), using a POVM-based construction of the compression isometry. The improved bound yields concrete quantum collision and preimage lower bounds for the sponge construction underlying SHA3 and the Davies-Meyer compression function used in SHA1 and SHA2, and is offered as a general tool for quantum security proofs involving random permutations or ideal ciphers.

arxiv.orgpaperAdded 24 Sep 2026, published 23 Sep 2026🛡️ Security