@inproceedings{8297,
  abstract     = {Designing a secure permissionless distributed ledger (blockchain) that performs on par with centralized payment
processors, such as Visa, is a challenging task. Most existing distributed ledgers are unable to scale-out, i.e., to grow their totalprocessing capacity with the number of validators; and those that do, compromise security or decentralization. We present OmniLedger, a novel scale-out distributed ledger that preserves longterm security under permissionless operation. It ensures security and correctness by using a bias-resistant public-randomness protocol for choosing large, statistically representative shards that process transactions, and by introducing an efficient crossshard commit protocol that atomically handles transactions affecting multiple shards. OmniLedger also optimizes performance via parallel intra-shard transaction processing, ledger pruning via collectively-signed state blocks, and low-latency “trust-butverify” 
validation for low-value transactions. An evaluation ofour experimental prototype shows that OmniLedger’s throughput
scales linearly in the number of active validators, supporting Visa-level workloads and beyond, while confirming typical transactions in under two seconds.},
  author       = {Kokoris Kogias, Eleftherios and Jovanovic, Philipp and Gasser, Linus and Gailly, Nicolas and Syta, Ewa and Ford, Bryan},
  booktitle    = {2018 IEEE Symposium on Security and Privacy},
  isbn         = {9781538643532},
  issn         = {2375-1207},
  location     = {San Francisco, CA, United States},
  pages        = {583--598},
  publisher    = {IEEE},
  title        = {{OmniLedger: A secure, scale-out, decentralized ledger via sharding}},
  doi          = {10.1109/sp.2018.000-5},
  year         = {2018},
}

@inproceedings{8306,
  abstract     = {Bias-resistant public randomness is a critical component in many (distributed) protocols. Generating public randomness is hard, however, because active adversaries may behave dishonestly to bias public random choices toward their advantage. Existing solutions do not scale to hundreds or thousands of participants, as is needed in many decentralized systems. We propose two large-scale distributed protocols, RandHound and RandHerd, which provide publicly-verifiable, unpredictable, and unbiasable randomness against Byzantine adversaries. RandHound relies on an untrusted client to divide a set of randomness servers into groups for scalability, and it depends on the pigeonhole principle to ensure output integrity, even for non-random, adversarial group choices. RandHerd implements an efficient, decentralized randomness beacon. RandHerd is structurally similar to a BFT protocol, but uses RandHound in a one-time setup to arrange participants into verifiably unbiased random secret-sharing groups, which then repeatedly produce random output at predefined intervals. Our prototype demonstrates that RandHound and RandHerd achieve good performance across hundreds of participants while retaining a low failure probability by properly selecting protocol parameters, such as a group size and secret-sharing threshold. For example, when sharding 512 nodes into groups of 32, our experiments show that RandHound can produce fresh random output after 240 seconds. RandHerd, after a setup phase of 260 seconds, is able to generate fresh random output in intervals of approximately 6 seconds. For this configuration, both protocols operate at a failure probability of at most 0.08% against a Byzantine adversary.},
  author       = {Syta, E. and Jovanovic, P. and Kokoris Kogias, Eleftherios and Gailly, N. and Gasser, L. and Khoffi, I. and Fischer, M. J. and Ford, B.},
  booktitle    = {2017 IEEE Symposium on Security and Privacy},
  isbn         = {9781509055340},
  issn         = {2375-1207},
  location     = {San Jose, CA, United States},
  pages        = {444--460},
  publisher    = {IEEE},
  title        = {{Scalable bias-resistant distributed randomness}},
  doi          = {10.1109/SP.2017.45},
  year         = {2017},
}