yusuke1997/dblp-id-title huggingface dataset:
Limitations of Information-theoretic Incompressible Encodings
Formal Analysis of a TTP-Free Blacklistable Anonymous Credentials System (Full Version)
A Block Cipher based PRNG Secure Against Side-Channel Key Recovery
Keyed Streebog is a secure PRF and MAC
A Configurable Crystals-Kyber Hardware Implementation with Side-Channel Protection
Do not rug on me: zero-dimensional scam detection
Exact Security Analysis of Hash-then-Mask Type Probabilistic MAC Constructions
Differential Power Analysis on (Non-)Linear Feedback Shift Registers
Differential Cryptanalysis of WARP
Qubit-based Unclonable Encryption with Key Recycling
Allocating Rotational Cryptanalysis based Preimage Attack on 4-round Keccak-224 for Quantum Setting
PQC: R-Propping of a New Group-Based Digital Signature
How to leverage hardness of constant-degree expanding polynomials over ℝ to build iO
SAFE: Sponge API for Field Elements
Factorization of a 768-bit RSA modulus
the upper bounds on differntial characteristics in block cipher SMS4
Breaking RSA with Overclocking-induced GPU Faults
Fast Algebraic Immunity of 2 m+2 & 2 m+3 variables Majority Function
Fast Quantum Algorithm for Solving Multivariate Quadratic Equations
Ciphers that Securely Encipher their own Keys
Evolutionary Construction of de Bruijn Sequences
Isogenies of Elliptic Curves: A Computational Approach
Quasar: Sublinear Accumulation Schemes for Multiple Instances
Golden: Lightweight Non-Interactive Distributed Key Generation
Optimized Computation of the Jacobi Symbol
It wasn't me! Repudiability and Unclaimability of Ring Signatures
Secondary constructions on generalized bent functions
Efficient Online/Offline Identity-Based Signature for Wireless Sensor Network
DiLizium 2.0: Revisiting Two-Party Crystals-Dilithium
Private Interactive Communication Across an Adversarial Channel
Counting Points for Hyperelliptic Curves of type y 2 x 5 +ax over Finite Prime Fields
A Diagonal Fault Attack on the Advanced Encryption Standard
A new class of semi-bent quadratic Boolean functions
The Limits of Provable Security Against Model Extraction
Admissible Parameters for the Crossbred Algorithm and Semi-regular Sequences over Finite Fields
A Successful Subfield Lattice Attack on a Fully Homomorphic Encryption Scheme
Balanced Quadratic Reliable Broadcast and Improved Asynchronous Verifiable Information Dispersal
A simple generalization of the ElGamal cryptosystem to non-abelian groups II
Transmitting Secrets by Transmitting only Plaintext
VERI-ZEXE: Decentralized Private Computation with Universal Setup
Do Not Trust in Numbers: Practical Distributed Cryptography With General Trust
An Extended Hierarchy of Security Notions for Threshold Signature Schemes and Automated Analysis of Protocols That Use Them
Practical Cryptanalysis of a Public-key Encryption Scheme Based on Non-linear Indeterminate Equations at SAC 2017
Private and Efficient Stable Marriages (Matching)
ML-Guided Beam Search for Differential Trail Discovery in SPN Ciphers: A Case Study on GIFT-64
A Fast Multiplication Algorithm and RLWE-PLWE Equivalence for the Maximal Real Subfield of the 2 r p s -th Cyclotomic Field
Lattice Signature can be as Simple as Lattice Encryption
Side Channel Attacks: Vulnerability Analysis of PRINCE and RECTANGLE using DPA
A novel algorithm enumerating Bent functions
Cryptanalysis of Full PRIDE Block Cipher
Random Number Generation Based on Oscillatory Metastability in Ring Circuits
Batch Decryption without Epochs and its Application to Encrypted Mempools
Distance Bounding based on PUF
Cryptanalysis of The Lifted Unbalanced Oil Vinegar Signature Scheme
Efficient oblivious transfer schemes
Non-Abelian Analogs of Lattice Rounding
High-Precision Exact FHE Made Simple, General, and Fast
Improving and Automating BFV Parameters Selection: An Average-Case Approach
Trapdoor Computational Fuzzy Extractors
Practical-Time Attacks Against Reduced Variants of MISTY1
Rank-metric Encryption on Arm-Cortex M0
On End-to-End Encryption
A Reusable Fuzzy Extractor with Practical Storage Size
An Efficient Algorithm for Solving the MQ Problem using Hilbert Series
Overlaying Circuit Clauses for Secure Computation
Two-party authenticated key exchange protocol using lattice-based cryptography
Fractional LWE: a nonlinear variant of LWE
On the security of the WOTS-PRF signature scheme
Deterministic-Prover Zero-Knowledge Proofs
Sponge based CCA2 secure asymmetric encryption for arbitrary length message
zkVoting : Zero-knowledge proof based coercion-resistant and E2E verifiable e-voting system
A Domain Transformation for Structure-Preserving Signatures on Group Elements
A Key-recovery Attack on 855-round Trivium
Post-quantum Cryptographic Analysis of SSH
A subfield lattice attack on overstretched NTRU assumptions: Cryptanalysis of some FHE and Graded Encoding Schemes
Orca: FSS-based Secure Training with GPUs
Unclonable Non-Interactive Zero-Knowledge
Lattice-Based Public Key Cryptosystem Provably Secure against Adaptive Chosen Ciphertext Attack
Do Not Bound to a Single Position: Near-Optimal Multi-Positional Mismatch Attacks Against Kyber and Saber
Towards Practical PFE: An Efficient 2-Party Private Function Evaluation Protocol Based on Half Gates
Approximating Addition by XOR: how to go all the way
The Mundja Streaming MAC
How to backdoor LWE-like cryptosystems
Multi-Recipient Public-Key Encryption with Shortened Ciphertext
Supporting Non-membership Proofs with Bilinear-map Accumulators
Highly-Efficient Universally-Composable Commitments based on the DDH Assumption
Unifying Compilers for SNARKs, SMT, and More
On the overflow and p-adic theory applied to homomorphic encryption
Verifying liquidity of Bitcoin contracts
Exploiting Collisions in Addition Chain-based Exponentiation Algorithms
Sublinear-Communication Secure Multiparty Computation does not require FHE
Ferveo: Threshold Decryption for Mempool Privacy in BFT networks
Some Observations on HC-128
Halka: A Lightweight, Software Friendly Block Cipher Using Ultra-lightweight 8-bit S-box
Iterated Inhomogeneous Polynomials
On Collisions of Hash Functions Turbo SHA-2
New Proxy Signature, Proxy Blind Signature and Proxy Ring Signature Schemes from Bilinear Pairing
Ethna: Channel Network with Dynamic Internal Payment Splitting
COCO: Coconuts and Oblivious Computations for Orthogonal Authentication
Strong Continuous Non-malleable Encoding Schemes with Tamper-Detection
A note on the optimality of frequency analysis vs. ℓ p -optimization
Public Key Block Cipher Based on Multivariate Quadratic Quasigroups
Quantum Attacks on HCTR and its Variants
Computation of Hilbert class polynomials and modular polynomials from supersingular elliptic curves
Evaluating Bernstein-Rabin-Winograd Polynomials
Cryptographer's Toolkit for Construction of 8-Bit Bent Functions
Secure positioning and quantum non-local correlations
Masked Computation the Floor Function and its Application to the FALCON Signature
Hardware Deployment of Hybrid PQC
On the Relations between Matchmaking Public Key Encryption and Public Key Authenticated Encryption with Keyword Search
Securing the Data in Big Data Security Analytics
Duplexing the sponge: single-pass authenticated encryption and other applications
Small Scale Variants Of The Block Cipher PRESENT
Broadcast Encryption with Size N^1/3 and More from k-Lin
Digital Signatures from Challenge-Divided Sigma-Protocols
On the security of Cubic UOV
Groth-Sahai Proofs Revisited Again: A Bug in "Optimized" Randomization
Authenticating Medications with QR-Codes and Compact Digital Signatures
MiniLedger: Compact-sized Anonymous and Auditable Distributed Payments
CNF-FSS and its Applications
On construction of signature schemes based on birational permutations over noncommutative rings
Speeding up lattice sieve with Xeon Phi coprocessor
SGXonerated: Finding (and Partially Fixing) Privacy Flaws in TEE-based Smart Contract Platforms Without Breaking the TEE
Key agreement based on homomorphisms of algebraic structures
Fast Multiplication and the PLWE-RLWE Equivalence for an Infinite Family of Cyclotomic Subextensions
Achieving GWAS with Homomorphic Encryption
Standard Model Leakage-Resilient Authenticated Key Exchange using Inner-product Extractors
Tile-Based Modular Architecture for Accelerating Homomorphic Function Evaluation on FPGA
MIFARE Classic: exposing the static encrypted nonce variant
Improving Differential-Neural Cryptanalysis with Inception Blocks
Simultaneous hashing of multiple messages
A New Post-Quantum Key Agreement Protocol and Derived Cryptosystem Based on Rectangular Matrices
uMine: a Blockchain based on Human Miners
Obfuscation and Outsourced Computation with Certified Deletion
Hardware Implementations of NIST Lightweight Cryptographic Candidates: A First Look
Simple and Efficient Approach for Achieving End-to-End Anonymous Communication
Ate pairing for y 2 =x 5 -αx in characteristic five
A non-PCP Approach to Succinct Quantum-Safe Zero-Knowledge
Cryptographic Hash-Function Basics: Definitions, Implications and Separations for Preimage Resistance, Second-Preimage Resistance, and Collision Resistance
Explicit Construction of Secure Frameproof Codes
A Countermeasure Against Statistical Ineffective Fault Analysis
Output Prediction Attacks on SPN Block Ciphers using Deep Learning
Identity-Based Cryptography for Cloud Security
Integrals go Statistical: Cryptanalysis of Full Skipjack Variants
Faster batch forgery identification
Managing Secrets with Consensus Networks: Fairness, Ransomware and Access Control
Lyra: Password-Based Key Derivation with Tunable Memory and Processing Costs
Single-Input Functionality against a Dishonest Majority: Practical and Round-Optimal
Spectral characterization of iterating lossy mappings
Quantum Cryptanalysis of NTRU
Rational Secret Sharing with Side Information in Point-to-Point Networks via Time-Delayed Encryption
The Maiorana-McFarland structure based cryptanalysis for Simon
Round-Optimal Multi-Party Computation with Identifiable Abort
A Second Pre-image Attack Against Elliptic Curve Only Hash (ECOH)
Analysis of TPL Signature Scheme
Sigmabus: Binding Sigmas in Circuits for Fast Curve Operations
Higher-order cryptanalysis of LowMC
First-Order Masked Kyber on ARM Cortex-M4
On CCZ-Equivalence, Extended-Affine Equivalence, and Function Twisting
Implications of the Nontriviality of Entropy Approximation
Truncation Untangled: Scaling Fixed-Point Arithmetic for Privacy-Preserving Machine Learning to Large Models and Datasets
ACCELERATING THE SCALAR MULTIPLICATION ON GENUS 2 HYPERELLIPTIC CURVE CRYPTOSYSTEMS
A note on the low order assumption in class group of an imaginary quadratic number fields
On asymptotically optimal tests for random number generators
Outrunning the Millennium FALCON: Speed Records for FALCON on FPGAs
Compounding Secret Sharing Schemes
Practical NFC Peer-to-Peer Relay Attack using Mobile Phones
Lightweight Sorting in Approximate Homomorphic Encryption
A Reduction-Based Proof for Authentication and Session Key Security in 3-Party Kerberos
From Non-Adaptive to Adaptive Pseudorandom Functions
Voting with Unconditional Privacy by Merging Prêt-à-Voter and PunchScan
New Monotone Span Programs from Old
Olingo: Threshold Lattice Signatures with DKG and Identifiable Abort
Fully Secure Attribute Based Encryption from Multilinear Maps
Breaking the provably secure SAKE-C authenticated key exchange protocol with Extended Key Compromise Impersonation (E-KCI) Attack
Explicit endomorphism of the Jacobian of a hyperelliptic function field of genus 2 using base field operations
Improved Constructions of Anonymous Credentials From Structure-Preserving Signatures on Equivalence Classes
A Digital Identity in the Hands of Swiss Citizens
Error-Detecting in Monotone Span Programs with Application to Communication Efficient Multi-Party Computation
SoK: Reassessing Side-Channel Vulnerabilities and Countermeasures in PQC Implementations
A Lattice-based Designated Verifier zkSNARK from Standard Assumptions
On the Estonian Internet Voting System, IVXV, SoK and Suggestions
Mova: Nova folding without committing to error terms
A time series approach for profiling attack
More results on Shortest Linear Programs
On Weak NIZKs, One-way Functions and Amplification
Entropic Quasigroup Based Secret Agreement Using Large Order Automorphisms
An ID-Based Key Agreement Protocol Based on ECC Among Users of Separate Networks
Practical-time Attack on the Full MMB Block Cipher
BADGER - Blockchain Auditable Distributed (RSA) key GEneRation
Improving Attacks on Speck32/64 using Deep Learning
Time-Specific Encryption with Constant-Size Secret-Keys Secure under Standard Assumption
Provable Speedups for SVP Approximation Under Random Local Blocks
A Class of 1-Resilient Function with High Nonlinearity and Algebraic Immunity
Optimized and secure pairing-friendly elliptic curves suitable for one layer proof composition
Key-Recovery Attack on a Public-Key Encryption Related to Planted Clique
Faster LEGO-based Secure Computation without Homomorphic Commitments
Low-Latency Linear Transformations with Small Key Transmission for Private Neural Network on Homomorphic Encryption
JHAE: An Authenticated Encryption Mode Based on JH
PI-Cut-Choo! Parallel Instance Cut and Choose for Practical Blind Signatures
Fast 4 way vectorized ladder for the complete set of Montgomery curves
Privacy-preserving biometric authentication: challenges and directions
Family of PRGs based on Collections of Arithmetic Progressions
Fully Homomorphic Encryption on Octonion Ring
Loop-abort faults on supersingular isogeny cryptosystems
Starlit: Privacy-Preserving Federated Learning to Enhance Financial Fraud Detection
Optimizing Liveness for Blockchain-Based Sealed-Bid Auctions in Rational Settings
On extended algebraic immunity
The SIP Security Enhanced by Using Pairing-assisted Massey-Omura Signcryption
Enhanced Cryptanalysis of Substitution Cipher Chaining mode (SCC-128)
Unified Approach to UOV-like Multivariate Signature Schemes
cq: Cached quotients for fast lookups
Do Not Disturb a Sleeping Falcon: Floating-Point Error Sensitivity of the Falcon Sampler and Its Consequences
Indifferentiability Results and Proofs for Some Popular Cryptographic Constructions
Somewhere Randomness Extraction and Security against Bounded-Storage Mass Surveillance
A Framework for the Cryptographic Verification of Java-like Programs
On Isogeny Graphs of Supersingular Elliptic Curves over Finite Fields
A Theoretical Take on a Practical Consensus Protocol
Round and Communication Efficient Unconditionally-secure MPC with t < n/3 in Partially Synchronous Network
Private Branching Programs: On Communication-Efficient Cryptocomputing
The low-call diet: Authenticated Encryption for call counting HSM users
New MILP Modeling: Improved Conditional Cube Attacks to Keccak-based Constructions
Efficiency Limitations for Sigma-Protocols for Group Homomorphisms
LIKE - Lattice Isomorphism-based Non-Interactive Key Exchange via Group Actions
Elastic AES
1. AES seems weak. 2. Linear time secure cryptography
Simple Soundness Proofs
Security Proofs for Participation Privacy and Stronger Veri ability for Helios
A Strong Blind Signature Scheme over Braid Groups
Constant time algorithms for ROLLO-I-128
Re-Randomize and Extract: A Novel Commitment Construction Framework Based on Group Actions
Further Constructions of Almost Resilient Functions
On the Pitfalls of Modeling Individual Knowledge
Constant-size Group Signatures from Lattices
Fast polynomial multiplication using matrix multiplication accelerators with applications to NTRU on Apple M1/M3 SoCs
Side-Channel Attacks on Lattice-Based KEMs Are Not Prevented by Higher-Order Masking
A secure Deniable Authentication Protocol based on Bilinear Diffie-Hellman Algorithm
Formally Assessing Cryptographic Entropy
Analysis of One Privacy-Preserving Electricity Data Classification Scheme Based on CNN Model With Fully Homomorphism
Distinguishing WPA
Expediting Homomorphic Computation via Multiplicative Complexity-aware Multiplicative Depth Minimization
CHVote System Specification
Universally Composable Interactive and Ordered Multi-Signatures
Balanced Boolean Functions with (more than) Maximum Algebraic Immunity
Bent functions stemming from Maiorana-McFarland class being provably outside its completed version
An Efficient One-move Nominative Signature Scheme
An Improved and Efficient Countermeasure against Power Analysis Attacks
Efficient Lattice-based Authenticated Encryption: A Practice-Oriented Provable Security Approach
Strong Designated Verifier Signatures with Non-delegatability from CSIDH
Finding the Impossible: Automated Search for Full Impossible Differential, Zero-Correlation, and Integral Attacks
Constant-rate Non-malleable Codes in the Split-state Model
Constructions of Efficiently Implementable Boolean Functions with Provable Nonlinearity/Resiliency/Algebraic Immunity Trade-Offs
Non-Interactive Blind Signatures for Random Messages
Cryptanalysis of some elliptic curve based cryptosystems of Paillier
Demand-aware Channel Topologies for Off-chain Blockchain Payments
Twisted Hessian Isogenies
Subversion-Resilient Authenticated Encryption without Random Oracles
Fault Analysis on the Stream Ciphers LILI-128 and Achterbahn
One-more Unforgeability of Blind ECDSA
On Trade-offs of Applying Block Chains for Electronic Voting Bulletin Boards
On the Minimum Number of Multiplications Necessary for Universal Hash Constructions
Toha Key Hardened Function
Tight Adaptive Simulation Security for Identity-based Inner-Product FE in the (Quantum) Random Oracle Model
A generalization of the Lucas addition chains
Lattice-Based Updatable Public-Key Encryption for Group Messaging
Complete characterization of generalized bent and 2^k-bent Boolean functions
Some thoughts on Collision Attacks in the Hash Functions MD5, SHA-0 and SHA-1
Multi-Hop Locks for Secure, Privacy-Preserving and Interoperable Payment-Channel Networks
All Proof of Work But No Proof of Play
A Simple Reduction from State Machine Replication to Binary Agreement in Partially Synchronous or Asynchronous Networks
A defect of the implementation schemes of the TTM cryptosystem
Thwarting Fault Attacks using the Internal Redundancy Countermeasure (IRC)
Deterministic algorithms for class group actions
Correlated Sequence Attack on Reduced-Round Simon-32/64 and Simeck-32/64
Fully Privacy-preserving Billing Models for Peer-to-Peer Electricity Trading Markets
AVX2 Implementation of QR-UOV for Modern x86 Processors
Magnetic RSA
A Solution to a Conjecture on the Maps χ n (k)
Efficient constant-time hashing to some elliptic curves of j-invariant 0
Improved Modeling for Substitution Boxes with Negative Samples and Beyond (Extended Version)
Implementation Study of Two Verifiable DelayFunctions
FRMAC, a Fast Randomized Message Authentication Code
PGC: Pretty Good Confidential Transaction System with Accountability
Revisiting subgroup membership testing on pairing-friendly curves via the Tate pairing
Security of Hedged Fiat-Shamir Signatures under Fault Attacks
Composite Algorithm The New Algorithm to Search for Monic Irreducible Polynomials over Extended Galois Fields
A Fast and Flexible Multi-Client Functional Encryption for Set Intersection
A Novel FPGA Architecture and Protocol for the Self-attestation of Configurable Hardware
Evasive LWE: Attacks, Variants & Obfustopia
Arithmetization of Σ¹₁ relations with polynomial bounds in Halo 2
Towards post-quantum secure PAKE - A tight security proof for OCAKE in the BPR model
The REESSE1+ Public Key Cryptosystem v2.2
PRE + : Dual of Proxy Re-encryption and Its Application
Vulnerability and Remedy of Stripped Function Logic Locking
Beyond the circuit: How to Minimize Foreign Arithmetic in ZKP Circuits
A Tale of Three Signatures: practical attack of ECDSA with wNAF
Area-time Efficient Implementation of NIST Lightweight Hash Functions Targeting IoT Applications
Algebraic Attacks on Human Identification Protocols
Garbled Neural Networks are Practical
Cut-and-Choose Based Two-Party Computation in the Online/Offline and Batch Settings
A Low-Area yet Performant FPGA Implementation of Shabal
Ramanujan Graphs and the Random Reducibility of Discrete Log on Isogenous Elliptic Curves
Lower Bound on Number of Compression Calls of a Collision-Resistance Preserving Hash
Overcoming the Worst-Case Curse for Cryptographic Constructions
Simulation-Based Selective Opening Security for Receivers under Chosen-Ciphertext Attacks
E fficient Identity-Based Encryption over NTRU Lattices
Efficient Zero-Knowledge Proofs for Commitments from Learning With Errors over Rings
Finding a polytope: A practical fault attack against Dilithium
Tailoring two-dimensional codes for structured lattice-based KEMs and applications to Kyber
Inapplicability of Differential Fault Attacks against Cellular Automata based Lightweight Authenticated Cipher
Isogeny graphs with maximal real multiplication
Anchored Merkle Range Proof for Pedersen Commitments
SoK: Multiparty Computation in the Preprocessing Model
Postponing the Glitches is Not Enough - A Critical Analysis of the DATE 2024 E-ISW Masking Scheme
Generalized Related-Key Rectangle Attacks on Block Ciphers with Linear Key Schedule
A provably secure ID-based ring signature scheme
A Simplified Quadratic Frobenius Primality Test
Improved Integral Attacks on Reduced Round Camellia
Reductions from module lattices to free module lattices, and application to dequantizing module-LLL
ZK-ProVer: Proving Programming Verification in Non-Interactive Zero-Knowledge Proofs
Automatic Search for the Linear (hull) Characteristics of ARX Ciphers: Applied to SPECK, SPARX, Chaskey and CHAM-64
A Practical and Fully Distributed E-Voting Protocol for the Swiss Context
Power Balanced Circuits for Leakage-Power-Attacks Resilient Design
When Can We Incrementally Prove Computations of Arbitrary Depth?
DAUnTLeSS: Data Augmentation and Uniform Transformation for Learning with Scalability and Security
Zipf's Law in Passwords
Supersingular Isogeny Oblivious Transfer
Voltage-based Covert Channels in Multi-Tenant FPGAs
Factoring Polynomials for Constructing Pairing-friendly Elliptic Curves
Quantum security proofs using semi-classical oracles
A New Family of Pairing-Friendly elliptic curves
Scalable, transparent, and post-quantum secure computational integrity
Overcoming the Hole In The Bucket: Public-Key Cryptography Resilient to Continual Memory Leakage
Full-Authority Data Sharing Systems: Ciphertext-Dependent Proxy Re-Encryption with Dynamic Key Generation
Speed and Area Optimized Parallel Higher-Radix Modular Multipliers
A Survey of ECDSA Threshold Signing
Optimized Privacy-Preserving Clustering with Fully Homomorphic Encryption
Revisiting Leakage-Resilient MACs and Succinctly-Committing AEAD: More Applications of Pseudo-Random Injections
HTCNN: High-Throughput Batch CNN Inference with Homomorphic Encryption for Edge Computing
Biclique cryptanalysis of MIBS-80 and PRESENT-80
Cryptographic applications of capacity theory: On the optimality of Coppersmith's method for univariate polynomials
Efficient Attributes for Anonymous Credentials (Extended Version)
On Black-Box Complexity of Universally Composable Security in the CRS model
Taphonomical Security: (DNA) Information with Foreseeable Lifespan
Signal Leakage Attack Meets Depth First Search: an Improved Approach on DXL Key Exchange Protocol
The Perils of Limited Key Reuse: Adaptive and Parallel Mismatch Attacks with Post-processing Against Kyber
New Constructions of Revocable Identity-Based Encryption from Multilinear Maps
PRESENT Full Round Emulation : Structural Flaws and Predictable Outputs
A Generalized Distributed RSA Key Generation
Anonymous Self-Credentials and their Application to Single-Sign-On
Thunderbolt: A Formally Verified Protocol for Off-Chain Bitcoin Transfers
Classification of 4-bit S-boxes for BOGI-permutation
Sieving for Shortest Vectors in Ideal Lattices: a Practical Perspective
Fast Boolean Queries with Minimized Leakage for Encrypted Databases in Cloud Computing
Silent Threshold Cryptography from Pairings: Expressive Policies in the Plain Model
A New Paradigm for Verifiable Secret Sharing
Out-of-Band Authenticated Group Key Exchange: From Strong Authentication to Immediate Key Delivery
The Uber-Knowledge Assumption: A Bridge to the AGM
Ofelimos: Combinatorial Optimization via Proof-of-Useful-Work \\ A Provably Secure Blockchain Protocol