---
_id: '8311'
abstract:
- lang: eng
text: 'One of the core promises of blockchain technology is that of enabling trustworthy
data dissemination in a trustless environment. What current blockchain systems
deliver, however, is slow dissemination of public data, rendering blockchain technology
unusable in settings where latency, transaction capacity, or data confidentiality
are important. In this thesis we focus on providing solutions on two of the most
pressing problems blockchain technology currently faces: scalability and data
confidentiality. To address the scalability issue, we present OMNILEDGER, a novel
scale-out distributed ledger that preserves long-term 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 cross-shard commit protocol that
atomically handles transactions affecting multiple shards. To enable secure sharing
of confidential data we present CALYPSO, the first fully decentralized, auditable
access-control framework for secure blockchain-based data sharing which builds
upon two abstractions. First, on-chain secrets enable collective management of
(verifiably shared) secrets under a Byzantine adversary where an access-control
blockchain enforces user-specific access rules and a secret-management cothority
administers encrypted data. Second, skipchain-based identity and access management
enables efficient administration of dynamic, sovereign identities and access policies
and, in particular, permits clients to maintain long-term relationships with respect
to evolving user identities thanks to the trust-delegating forward links of skipchains.
In order to build OMNILEDGER and CALYPSO, we first build a set of tools for efficient
decentralization, which are presented in Part II of this dissertation. These tools
can be used in decentralized and distributed systems to achieve (1) scalable consensus
(BYZCOIN), (2) bias- resistant distributed randomness creations (RANDHOUND), and
(3) relationship-keeping between independently updating communication endpoints
(SKIPCHAINIAC). Although we use this tools in the scope off this thesis, they
can be (and already have been) used in a far wider scope.'
article_processing_charge: No
author:
- first_name: Eleftherios
full_name: Kokoris Kogias, Eleftherios
id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
last_name: Kokoris Kogias
citation:
ama: Kokoris Kogias E. Secure, confidential blockchains providing high throughput
and low latency. 2019. doi:10.5075/epfl-thesis-7101
apa: Kokoris Kogias, E. (2019). Secure, confidential blockchains providing high
throughput and low latency. École Polytechnique Fédérale de Lausanne. https://doi.org/10.5075/epfl-thesis-7101
chicago: Kokoris Kogias, Eleftherios. “Secure, Confidential Blockchains Providing
High Throughput and Low Latency.” École Polytechnique Fédérale de Lausanne, 2019.
https://doi.org/10.5075/epfl-thesis-7101.
ieee: E. Kokoris Kogias, “Secure, confidential blockchains providing high throughput
and low latency,” École Polytechnique Fédérale de Lausanne, 2019.
ista: Kokoris Kogias E. 2019. Secure, confidential blockchains providing high throughput
and low latency. École Polytechnique Fédérale de Lausanne.
mla: Kokoris Kogias, Eleftherios. Secure, Confidential Blockchains Providing
High Throughput and Low Latency. École Polytechnique Fédérale de Lausanne,
2019, doi:10.5075/epfl-thesis-7101.
short: E. Kokoris Kogias, Secure, Confidential Blockchains Providing High Throughput
and Low Latency, École Polytechnique Fédérale de Lausanne, 2019.
date_created: 2020-08-27T11:22:24Z
date_published: 2019-09-27T00:00:00Z
date_updated: 2021-12-20T15:30:47Z
day: '27'
degree_awarded: PhD
doi: 10.5075/epfl-thesis-7101
extern: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.doi.org/10.5075/epfl-thesis-7101
month: '09'
oa: 1
oa_version: Published Version
page: '244'
publication_status: published
publisher: École Polytechnique Fédérale de Lausanne
status: public
supervisor:
- first_name: Bryan Alexander
full_name: Ford, Bryan Alexander
last_name: Ford
title: Secure, confidential blockchains providing high throughput and low latency
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2019'
...
---
_id: '8314'
abstract:
- lang: eng
text: "Off-chain protocols (channels) are a promising solution to the scalability
and privacy challenges of blockchain payments. Current proposals, however, require
synchrony assumptions to preserve the safety of a channel, leaking to an adversary
the exact amount of time needed to control the network for a successful attack.
In this paper, we introduce Brick, the first payment channel that remains secure
under network asynchrony and concurrently provides correct incentives. The core
idea is to incorporate the conflict resolution process within the channel by introducing
a rational committee of external parties, called Wardens. Hence, if a party wants
to close a channel unilaterally, it can only get the committee's approval for
the last valid state. Brick provides sub-second latency because it does not employ
heavy-weight consensus. Instead,\r\nBrick uses consistent broadcast to announce
updates and close the channel, a light-weight abstraction that is powerful enough
to preserve safety and liveness to any rational parties. Furthermore, we consider
permissioned blockchains, where the additional property of auditability might
be desired for regulatory purposes. We introduce Brick+, an off-chain construction
that provides auditability on top of Brick without conflicting with its privacy
guarantees. We formally define the properties our payment channel construction
should fulfill, and prove that both Brick and Brick+ satisfy them. We also design
incentives for Brick such that honest and rational behavior aligns. Finally, we
provide a reference implementation of the smart contracts in Solidity."
article_number: '1905.11360'
article_processing_charge: No
author:
- first_name: Georgia
full_name: Avarikioti, Georgia
last_name: Avarikioti
- first_name: Eleftherios
full_name: Kokoris Kogias, Eleftherios
id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
last_name: Kokoris Kogias
- first_name: Roger
full_name: Wattenhofer, Roger
last_name: Wattenhofer
- first_name: Dionysis
full_name: Zindros, Dionysis
last_name: Zindros
citation:
ama: 'Avarikioti G, Kokoris Kogias E, Wattenhofer R, Zindros D. Brick: Asynchronous
payment channels. arXiv.'
apa: 'Avarikioti, G., Kokoris Kogias, E., Wattenhofer, R., & Zindros, D. (n.d.).
Brick: Asynchronous payment channels. arXiv.'
chicago: 'Avarikioti, Georgia, Eleftherios Kokoris Kogias, Roger Wattenhofer, and
Dionysis Zindros. “Brick: Asynchronous Payment Channels.” ArXiv, n.d.'
ieee: 'G. Avarikioti, E. Kokoris Kogias, R. Wattenhofer, and D. Zindros, “Brick:
Asynchronous payment channels,” arXiv. .'
ista: 'Avarikioti G, Kokoris Kogias E, Wattenhofer R, Zindros D. Brick: Asynchronous
payment channels. arXiv, 1905.11360.'
mla: 'Avarikioti, Georgia, et al. “Brick: Asynchronous Payment Channels.” ArXiv,
1905.11360.'
short: G. Avarikioti, E. Kokoris Kogias, R. Wattenhofer, D. Zindros, ArXiv (n.d.).
date_created: 2020-08-27T11:36:54Z
date_published: 2019-05-27T00:00:00Z
date_updated: 2021-01-12T08:18:04Z
day: '27'
extern: '1'
external_id:
arxiv:
- '1905.11360'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1905.11360
month: '05'
oa: 1
oa_version: Preprint
publication: arXiv
publication_status: submitted
status: public
title: 'Brick: Asynchronous payment channels'
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2019'
...
---
_id: '8315'
abstract:
- lang: eng
text: "Sharding distributed ledgers is the most promising on-chain solution for
scaling blockchain technology. In this work, we define and analyze the properties
a sharded distributed ledger should fulfill. More specifically, we show that a
sharded blockchain cannot be scalable under a fully adaptive adversary, but it
can scale up to $O(n/\\log n)$ under an epoch-adaptive adversary. This is possible
only if the distributed ledger creates succinct proofs of the valid state updates
at the end of each epoch. Our model builds upon and extends the Bitcoin backbone
protocol by defining consistency and\r\nscalability. Consistency encompasses the
need for atomic execution of cross-shard transactions to preserve safety, whereas
scalability encapsulates the speedup a sharded system can gain in comparison to
a non-sharded system. In\r\norder to show the power of our framework, we analyze
the most prominent sharded blockchains and either prove their correctness (OmniLedger,
RapidChain) under our model or pinpoint where they fail to balance the consistency
and\r\nscalability requirements (Elastico, Monoxide). "
article_number: '1910.10434'
article_processing_charge: No
author:
- first_name: Georgia
full_name: Avarikioti, Georgia
last_name: Avarikioti
- first_name: Eleftherios
full_name: Kokoris Kogias, Eleftherios
id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
last_name: Kokoris Kogias
- first_name: Roger
full_name: Wattenhofer, Roger
last_name: Wattenhofer
citation:
ama: 'Avarikioti G, Kokoris Kogias E, Wattenhofer R. Divide and scale: Formalization
of distributed ledger sharding protocols. arXiv.'
apa: 'Avarikioti, G., Kokoris Kogias, E., & Wattenhofer, R. (n.d.). Divide and
scale: Formalization of distributed ledger sharding protocols. arXiv.'
chicago: 'Avarikioti, Georgia, Eleftherios Kokoris Kogias, and Roger Wattenhofer.
“Divide and Scale: Formalization of Distributed Ledger Sharding Protocols.” ArXiv,
n.d.'
ieee: 'G. Avarikioti, E. Kokoris Kogias, and R. Wattenhofer, “Divide and scale:
Formalization of distributed ledger sharding protocols,” arXiv. .'
ista: 'Avarikioti G, Kokoris Kogias E, Wattenhofer R. Divide and scale: Formalization
of distributed ledger sharding protocols. arXiv, 1910.10434.'
mla: 'Avarikioti, Georgia, et al. “Divide and Scale: Formalization of Distributed
Ledger Sharding Protocols.” ArXiv, 1910.10434.'
short: G. Avarikioti, E. Kokoris Kogias, R. Wattenhofer, ArXiv (n.d.).
date_created: 2020-08-27T11:37:43Z
date_published: 2019-10-23T00:00:00Z
date_updated: 2021-01-12T08:18:05Z
day: '23'
extern: '1'
external_id:
arxiv:
- '1910.10434'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1910.10434
month: '10'
oa: 1
oa_version: Preprint
publication: arXiv
publication_status: submitted
status: public
title: 'Divide and scale: Formalization of distributed ledger sharding protocols'
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2019'
...
---
_id: '8313'
abstract:
- lang: eng
text: The present invention concerns a computer-implemented method for secure data
exchange between a sender (A) and a recipient (B), wherein the method is performed
by the sender (A) and comprises encrypting data using a symmetric key k, creating
a write transaction T W , wherein the write transaction T W comprises information
usable to derive the symmetric key k and an access policy identifying the recipient
(B) as being allowed to decrypt the encrypted data, providing the recipient (B)
access to the encrypted data, and sending the write transaction T W to a first
group of servers (AC) for being stored in a blockchain data structure maintained
by the first group of servers (AC).
applicant:
- 'École Polytechnique Fédérale De Lausanne '
article_processing_charge: No
author:
- first_name: Bryan
full_name: Ford, Bryan
last_name: Ford
- first_name: Linus
full_name: Gasser, Linus
last_name: Gasser
- first_name: Eleftherios
full_name: Kokoris Kogias, Eleftherios
id: f5983044-d7ef-11ea-ac6d-fd1430a26d30
last_name: Kokoris Kogias
- first_name: Philipp
full_name: Janovic, Philipp
last_name: Janovic
citation:
ama: Ford B, Gasser L, Kokoris Kogias E, Janovic P. Methods and systems for secure
data exchange. 2019.
apa: Ford, B., Gasser, L., Kokoris Kogias, E., & Janovic, P. (2019). Methods
and systems for secure data exchange.
chicago: Ford, Bryan, Linus Gasser, Eleftherios Kokoris Kogias, and Philipp Janovic.
“Methods and Systems for Secure Data Exchange,” 2019.
ieee: B. Ford, L. Gasser, E. Kokoris Kogias, and P. Janovic, “Methods and systems
for secure data exchange.” 2019.
ista: Ford B, Gasser L, Kokoris Kogias E, Janovic P. 2019. Methods and systems for
secure data exchange.
mla: Ford, Bryan, et al. Methods and Systems for Secure Data Exchange. 2019.
short: B. Ford, L. Gasser, E. Kokoris Kogias, P. Janovic, (2019).
date_created: 2020-08-27T11:24:44Z
date_published: 2019-08-22T00:00:00Z
date_updated: 2022-01-05T14:00:32Z
day: '22'
extern: '1'
ipc: G06F21/62 ; H04L9/08 ; H04L9/32
ipn: WO2019158209 (A1)
main_file_link:
- open_access: '1'
url: https://patents.google.com/patent/WO2019158209A1
month: '08'
oa: 1
oa_version: Published Version
publication_date: 2019-08-22
status: public
title: Methods and systems for secure data exchange
type: patent
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2019'
...
---
_id: '8405'
abstract:
- lang: eng
text: Atomic-resolution structure determination is crucial for understanding protein
function. Cryo-EM and NMR spectroscopy both provide structural information, but
currently cryo-EM does not routinely give access to atomic-level structural data,
and, generally, NMR structure determination is restricted to small (<30 kDa) proteins.
We introduce an integrated structure determination approach that simultaneously
uses NMR and EM data to overcome the limits of each of these methods. The approach
enables structure determination of the 468 kDa large dodecameric aminopeptidase
TET2 to a precision and accuracy below 1 Å by combining secondary-structure information
obtained from near-complete magic-angle-spinning NMR assignments of the 39 kDa-large
subunits, distance restraints from backbone amides and ILV methyl groups, and
a 4.1 Å resolution EM map. The resulting structure exceeds current standards of
NMR and EM structure determination in terms of molecular weight and precision.
Importantly, the approach is successful even in cases where only medium-resolution
cryo-EM data are available.
article_number: '2697'
article_processing_charge: No
article_type: original
author:
- first_name: Diego F.
full_name: Gauto, Diego F.
last_name: Gauto
- first_name: Leandro F.
full_name: Estrozi, Leandro F.
last_name: Estrozi
- first_name: Charles D.
full_name: Schwieters, Charles D.
last_name: Schwieters
- first_name: Gregory
full_name: Effantin, Gregory
last_name: Effantin
- first_name: Pavel
full_name: Macek, Pavel
last_name: Macek
- first_name: Remy
full_name: Sounier, Remy
last_name: Sounier
- first_name: Astrid C.
full_name: Sivertsen, Astrid C.
last_name: Sivertsen
- first_name: Elena
full_name: Schmidt, Elena
last_name: Schmidt
- first_name: Rime
full_name: Kerfah, Rime
last_name: Kerfah
- first_name: Guillaume
full_name: Mas, Guillaume
last_name: Mas
- first_name: Jacques-Philippe
full_name: Colletier, Jacques-Philippe
last_name: Colletier
- first_name: Peter
full_name: Güntert, Peter
last_name: Güntert
- first_name: Adrien
full_name: Favier, Adrien
last_name: Favier
- first_name: Guy
full_name: Schoehn, Guy
last_name: Schoehn
- first_name: Paul
full_name: Schanda, Paul
id: 7B541462-FAF6-11E9-A490-E8DFE5697425
last_name: Schanda
orcid: 0000-0002-9350-7606
- first_name: Jerome
full_name: Boisbouvier, Jerome
last_name: Boisbouvier
citation:
ama: Gauto DF, Estrozi LF, Schwieters CD, et al. Integrated NMR and cryo-EM atomic-resolution
structure determination of a half-megadalton enzyme complex. Nature Communications.
2019;10. doi:10.1038/s41467-019-10490-9
apa: Gauto, D. F., Estrozi, L. F., Schwieters, C. D., Effantin, G., Macek, P., Sounier,
R., … Boisbouvier, J. (2019). Integrated NMR and cryo-EM atomic-resolution structure
determination of a half-megadalton enzyme complex. Nature Communications.
Springer Nature. https://doi.org/10.1038/s41467-019-10490-9
chicago: Gauto, Diego F., Leandro F. Estrozi, Charles D. Schwieters, Gregory Effantin,
Pavel Macek, Remy Sounier, Astrid C. Sivertsen, et al. “Integrated NMR and Cryo-EM
Atomic-Resolution Structure Determination of a Half-Megadalton Enzyme Complex.”
Nature Communications. Springer Nature, 2019. https://doi.org/10.1038/s41467-019-10490-9.
ieee: D. F. Gauto et al., “Integrated NMR and cryo-EM atomic-resolution structure
determination of a half-megadalton enzyme complex,” Nature Communications,
vol. 10. Springer Nature, 2019.
ista: Gauto DF, Estrozi LF, Schwieters CD, Effantin G, Macek P, Sounier R, Sivertsen
AC, Schmidt E, Kerfah R, Mas G, Colletier J-P, Güntert P, Favier A, Schoehn G,
Schanda P, Boisbouvier J. 2019. Integrated NMR and cryo-EM atomic-resolution structure
determination of a half-megadalton enzyme complex. Nature Communications. 10,
2697.
mla: Gauto, Diego F., et al. “Integrated NMR and Cryo-EM Atomic-Resolution Structure
Determination of a Half-Megadalton Enzyme Complex.” Nature Communications,
vol. 10, 2697, Springer Nature, 2019, doi:10.1038/s41467-019-10490-9.
short: D.F. Gauto, L.F. Estrozi, C.D. Schwieters, G. Effantin, P. Macek, R. Sounier,
A.C. Sivertsen, E. Schmidt, R. Kerfah, G. Mas, J.-P. Colletier, P. Güntert, A.
Favier, G. Schoehn, P. Schanda, J. Boisbouvier, Nature Communications 10 (2019).
date_created: 2020-09-17T10:28:25Z
date_published: 2019-06-19T00:00:00Z
date_updated: 2021-01-12T08:19:03Z
day: '19'
doi: 10.1038/s41467-019-10490-9
extern: '1'
external_id:
pmid:
- '31217444'
intvolume: ' 10'
keyword:
- General Biochemistry
- Genetics and Molecular Biology
- General Physics and Astronomy
- General Chemistry
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1038/s41467-019-10490-9
month: '06'
oa: 1
oa_version: Published Version
pmid: 1
publication: Nature Communications
publication_identifier:
issn:
- 2041-1723
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
status: public
title: Integrated NMR and cryo-EM atomic-resolution structure determination of a half-megadalton
enzyme complex
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 10
year: '2019'
...