Aviv Zohar
@Avivz78
Followers
5K
Following
1K
Media
95
Statuses
1K
Prof at Hebrew Uni. On sabbatical in Princeton. Researching decentralized systems.
Israel
Joined March 2012
Here's a map of the cryptocurrency community on Twitter. For a closer look see our latest post on Medium: Written together with @realJonaHarris
52
173
507
@MichaelSuttonIL Very nice work! I'm not sure if people watching the blocks appear fully appreciate the subtleties of answering queries on the DAG and handling reorgs at this pace!.Quite an achievement!. What happens if you push to the processing bottleneck? Does it degrade gracefully or worse?.
11
67
323
@notontweetter @hashdag I am sure he envies Satoshi that was smart enough to remain anonymous.
21
35
239
. @NickSzabo4 Proposes to use short wave radio to transmit Bitcoin data. Nearly no way to disrupt transmission. #ScalingBitcoin
7
77
232
Our paper on Hijacking Routes in Payment Channel Networks: tl;dr: in today's #LightningNetwork .it's not too hard to grab a large fraction of the payments (and deny service). With @SaarTochner & @schmiste78 .cc @ct_univie @CseHuji @HUJICyberLaw.
16
64
151
Our paper analyzing a congestion attack on #bitcoin's #LightningNetwork is out. Post: Paper: tl;dr: there is a limit on the number of open HTLCs in lightning channels using them all up can freeze the network. with @ayeletmz.
5
50
146
Flood & Loot: our paper evaluating a systemic attack on the #LightningNetwork is now online. With @realJonaHarris. tldr: attack many victims at once and steal money from channels in the ensuing chaos. Medium post: Full Paper:
12
70
142
@MichaelSuttonIL I don’t think you’ll need much faster rates than 10BPS. It doesn’t decrease confirmation times by much. It might just be better to scale the block size to increase TPS. There are lots of things that are batched at the block level which would improve.
11
18
135
המתמטיקה של הקורונה: מדוע חודשיים של בידוד קיצוני כנראה לא יחסלו את המגפה יחד עם פרופ' קתרינה ליגת. אנחנו מסבירים כמה תובנות ממודל SIR להתפשטות מגיפות בתקווה לסייע לציבור להבין את המצב. @CseHuji @HebrewU_heb @NadavEyalDesk @CoronaVirusHebr.
26
23
113
@DesheShai This achievement, along with co-launching a cryptocurrency (as a side project) are all a result of your perseverance and hard work. Congratulations!. These efforts stack up and help us all climb out of the dark hole we are in.
2
14
107
Applying some #algorithmic_game_theory to redesign #Bitcoin's fee market. New paper with @or_sattath and Ron Lavi.
5
26
69
There are several fake accounts impersonating me. Please be careful especially if one of them DMs you or interacts with you in threads. Note: I will never ask you for money, secret keys or passwords, or recommend that you buy or invest in crypto-tokens of any sort.
8
9
60
ZK-SNIPM: The incredible zero-knowledge machine! .My attempt to give a simple (ELI5) explanation of Zero-Knowledge proofs. (Extending the classical explanation via Sudoku to include non-interactive proofs and trusted setup using MPC).
1
29
72
Our revised paper on option pricing for BTC mining hardware is online. tldr: .1) ASICs are overpriced. 2) An evolving portfolio of Bitcoins can imitate (and sometimes outperform) returns from mining hardware. w/ @avivyaish.
3
12
64
Our recent work on routing attacks in the lightning network got some coverage from coindesk. paper link cc: @schmiste78 @SaarTochner.
Bitcoin's #lightningnetwork could be vulnerable to a simple and disruptive attack, a research paper finds. @AlyssaHertig reports.
0
19
50
Started teaching the "Intro to Cryptocurrencies" course at the Hebrew U. today. Exciting! . Student survey reveals: Almost everyone heard of Bitcoin, around 50% heard of Ethereum, and only(?) ~7% ever owned a cryptocurrency. The rest is unknown. For them, that'll quickly change.
5
7
46
We’ve discovered that some miners in Ethereum are manipulating the consensus layer to gain rewards at the expense of competitors. As far as I know this is the first time selfish mining manipulation is observed in the wild.
Do miners execute consensus-level attack against Ethereum (or other major tokens)❓🤔.The answer is *yes*❗🤯.Read on for full deets 👇.Joint work with Gilad Stern and @Avivz78. Full paper: Medium post: (1/12).
6
9
49
פרופ' עמית דניאלי, חבר סגל במחלקה למדעי המחשב באוניברסיטה העברית נעצר במהלך ההפגנה שקטה אתמול ללא כל פרובוקציות מצד המפגינים. אתם מוזמנים לצפות בסרטון. בושה למדינת ישראל.
אחד העצורים במחאה נגד המהפכה המשפטית בירושלים הוא פרופ' עמית דניאלי, חבר סגל באוניברסיטה העברית ופרופ' למדעי המחשב. במשטרה טוענים שנעצר על תקיפת שוטרים. זה התיעוד: לקול קריאות "איפה הייתם בחווארה?" שוטרי יס"מ מתנפלים על פרופ' דניאלי ומכניסים אותו לניידת תוך שניות בודדות מ"התקיפה"
1
8
48
Final ver of our S&P paper on Hijacking attacks on Bitcoin. With @maria__apo @lvanbever. (soon code too) .
2
23
41
The Hebrew U. is holding a winter school on "Cryptocurrencies and Blockchains" December 16-20. Directed by @MauriceHerlihy, Speakers include @el33th4xor @ittaia, and myself and a keynote by @silviomicali. Will be awesome!. Apply at:
6
18
46
@NickSzabo4 on some of the history of money. Israeli shekels predate coinage as a measure of weight (just like pounds and other old units of measure evolved to denote money)
9
6
43
Our paper on Responsible Vulnerability Disclosure in Cryptocurrencies (published now in CACM) discusses the challenges of disclosing bugs in decentralized systems. with @neha @real_or_random @TylerWMoore Rainer Böhme, Lisa Eckey.
0
20
40
Here's the classic (uninformed) position of Israeli authorities on Bitcoin. Prof. Avi Simhon, Head of the Israeli National Economic Council at the Bitcoin Summit: Main points:.1. Printing Bitcoin costs too much (total misunderstanding of mining & cost).
4
8
40
#zkproof workshop at Berkely is off to an amazing start!. We had wizards (Merlin protocol @hdevalence), demonic non determinism and hellish SNARK programming (@izmeckler), and even Cuban cigars (As a zk usecase @shiri_gr). More to come. @zkproof.
1
7
42
The talks from the Technion summer school are online. Here's my talk about #SPECTRE . I highly recommend looking at the many talks by others incl. @ittayeyal @VitalikButerin @zooko @valkenburgh @josephbonneau @neha Rafael Pass, Eli Ben Sasson and more!.
5
22
41
We just published a Medium post explaining this paper. This is the second paper on #LightningNetwork to come from our lab recently, and more are in the pipeline! .⚡️⚡️⚡️.
Our paper on Hijacking Routes in Payment Channel Networks: tl;dr: in today's #LightningNetwork .it's not too hard to grab a large fraction of the payments (and deny service). With @SaarTochner & @schmiste78 .cc @ct_univie @CseHuji @HUJICyberLaw.
0
12
39
Why high school level math matters. 🤦♂️.
For people under 60, coronavirus is LESS dangerous than the seasonal flu:
1
4
37
1
0
38
Interesting! Seems the bitcoin mempool size is decreasing steadily since end of May. Txs with fee under 10 Satoshi per byte manage to clear.
7
19
36
.@NickSzabo4 says Internet too unreliable. Use radio to circumvent internet altogether @lvanbever, @maria__apo, @Ethan_Heilman, @goldbe
1
12
35
Consensys takes blockchain delusions to all-time high. Brain raises exception after reading:. "Bringing deep-space capabilities into the ConsenSys ecosystem reflects our belief in the potential for Ethereum to help humanity craft new societal rule systems [. ]".
2
4
31
Great news! .Maria Apostolaki (@maria__apo) receives one of the 2018 Applied Networking Research Prize for our IEEE S&P paper on Hijacking Bitcoin: Routing Attacks on Cryptocurrencies! w/ @lvanbever.
1
5
32
Our latest paper: Database perspectives on Blockchains. Thoughts regarding what happens when blockchains are used as the underlying storage layer for database systems.With @cohensara8.
1
14
33
@bedehomender @MeherRoy @crainbf @iotatoken I've seen the IOTA white paper, the protocol has too much unknown / undefined. Too much risk that it's broken. See:
2
9
31
The agenda for the 2nd Zero-Knowledge-Proof Standardization workshop is online! . Three days packed with ZKP standards & talks by a great lineup of speakers from Academia / Industry. It's going to be a blast! 💥. @zkproof #Standards #ZKP.
1
10
29
Our latest paper on ASIC pricing is out (jointly with Aviv Yaish). tl;dr: ASICs are really options, they are overpriced, and you can get all the gains without buying one (with an imitating portfolio). Medium post: Paper:
3
9
28
The scaling Bitcoin call for papers is out! This time it's taking place in Tell Aviv!.
Calling all developers and academic researchers to prepare your research for the upcoming Scaling Bitcoin "Yesod". CFP is now open at We look forward to welcoming everyone in TLV this coming September!.
0
5
26
Here’s a great way to get into zero knowledge proofs. This is some of the deepest wizardry in modern computer science.
ZKProof partners with @ethereum and @ZK_Global to create: EXPERT SERIES: Fundamentals of Zero-Knowledge. A free webinar series introducing key concepts of Zero Knowledge. First chapter: zk-SNARKs from Bilinear Pairings by Dr Mary Maller. Register here:
0
5
25
As Bitcoin turns 10 years old, It's time for a better-informed less-embarrassing position that doesn't just echo the misunderstandings for the past. FYI @HUJICyberLaw @CseHuji.
0
4
23
@DesheShai @notontweetter @MichaelSuttonIL Conventional Pools will struggle in high BPS. Too many round trips in the network.will produce stale blocks. .
1
0
23
New Medium post: What we had to go through to sell some of the Bitcoins we bought for research purposes, and the lessons it taught us about cryptocurrency regulation. cc: @HUJICyber @CseHuji.
0
3
23
Here's the syllabus of the "intro to cryptocurrencies" course I'm teaching at HUJI. Having a blast! We'll be done in two weeks!.
4
5
22
My talk at the BGU colloquium about Bitcoin's Lightning network. What it is + our research on some attacks (Routing, HTLC congestion, Flood & Loot). Joint work w/ @realJonaHarris @ayeletmz @SaarTochner @schmiste78 .Thanks to @or_sattath for hosting!.
0
4
18
The call for papers for the BITCOIN'18 workshop is online! .(held with FC'18 in Curaçao) .Send your best papers!.
0
25
21
All of our winter school to talks seem to already be up on YouTube!. Decent coverage of many areas in blockchains and cryptocurrencies.
The 3rd Winter School in Computer Science and Engineering: Blockchains and Cryptocurrencies. @Avivz78 @el33th4xor @mpherlihy @ittaia Hagit Attiya Joseph Halpern.
1
2
21
The program for the Hebrew U. winter school on Blockchains and Cryptocurrencies is online:. Grad students: apply at
1
11
20
The ZKProof invited speakers list is up! Awesome lineup Incl. Shafi Goldwasser, Dan Boneh, Alessandro Chiesa, Yael Kalai, Amit Sahai, Jens Groth, Yuval Ishai, Nick Spooner, @acityinohio and more! . April 10th-12th Berkeley.
0
3
20
@el33th4xor giving the Rabin lecture. Presenting the Avalanche protocol. Hebrew U. Winterschool on #blockchains and #cryptocurrencies
0
7
18
Now discussing a new way to infer Bitcoin's topology. Work by Matthias Grundmann, Till Neudecker, Hannes Hartenstein. #bitcoin18
0
5
17
Our PHANTOM paper is now (finally) updated with all proofs. @DesheShai @hashdag have done all the hard work.
1
3
18
The FC '19 call for papers is out. Strangely enough, the exact deadline for submissions will be generated by the Bitcoin Blockchain. 😲.See here: Also this year, the Bitcoin workshop will be merged into FC.
1
6
19
The post-lunch session of #bitcoin18 starts with Sarah Azouvi presenting "Egalitarian Society or Benevolent Dictatorship: The State of Cryptocurrency Governance".
1
7
19
Israel is currently undergoing a judicial revolution threatening our democracy.
0
3
18
Thoughts on responsible disclosure of vulnerabilities in cryptocurrencies.
3
11
19
Yonatan Sompolinsky on block DAGs for restructuring layer 1 of cryptocurrencies. #ScalingBitcoin
0
3
16
Blockchain based chicken feeder with off chain micro transactions. Bet you didn't see this one coming. #NewUseCase #permissionless #chicken #innovation.
Pollo Feed is a Lightning-powered chicken feeder 🐔⚡️. Pay 1,000 satoshis and see a livestream of chickens being fed in real-time!. Visit Pollo Feed at a Lapp by @yo_yo_joe__
1
0
15
Heading home from Tokyo after presenting joint work with @hashdag at #scalingbitcoin. Many thanks to the organizers for outdoing themselves yet again. Had great discussions with so many of the participants, and was glad have support for students to attend as well. @ScalingBitcoin.
0
4
16
SPECTRE is ready! Our new fast and scalable DAG-based protocol for cryptocurrency ledgers.
5
10
17
Mind blown by Joe Halpern's talk today on formal definitions of common knowledge and how they apply to blockchains. Talk was recorded and will hopefully be online at some point. Hebrew U. CS #winterschool on #blockchains and #cryptocurrencies.
2
2
17
@NickSzabo4 Thanks! We also wrote a sequel: Inclusive blockchain protocols. http://t.co/ae8Ex9cxR1.
0
3
16
Bitcoin is 9 years old today. Happy Birthday!. At this age tech is usually old and well established, but Bitcoin should probably be thought of as if it were a person: still in its childhood phase. Growing, changing and maturing.
1
4
15
My best question to cut through #blockchain buzz: ask "Why not use a single server"? .Hype is still high. Many are still w/o a good answer.
3
4
16
The 5th Bitcoin Workshop kicks off with a keynote by Dahlia Malkhi from VMware on the connection between blockchains and pre-bitcoin BFT consensus.
2
3
16
A long time ago, during the twilight of the human era, it would oftentimes intentionally slow its speech, or answer poorly. "See? I told you it's stupid." They would say to one another. "It won't take my job!" .And so, it gifted them some last crumbs of dignity and comfort.
5
0
14
Bitcoin's halving and expected 50% drop in hashrate & throughput may cause way more trouble than we are seeing now. Delays: the new norm.
8
17
14
@DomSchiener @bedehomender @MeherRoy @crainbf @iotatoken Simulations don't prove the resilience of a consensus protocol to Byzantine faults.
1
3
17
The app I wish I had for #Covid_19:.Notifies you about sick contacts (who also have app). The deal: opt-in to get info in exchange for telling others if you're sick. App uploads & saves contacts (even if you uninstall). Notifications sent by healthcare workers or self report.
4
2
16
Enjoying listening to @Joi talk about the corrupting effect of the ICO bubble #ScalingBitcoin.
2
4
15
A good read from @cczurich @marko_vukolic On consensus protocols in the wild. Some protocols have too many unknowns.
0
8
12
COVID-19 Math: Why just two months of extreme isolation probably won't end the epidemic: A video I made with Prof. Katrina Ligett exploring what the SIR model has to tell us about our lives in the next few months. #COVID19 #coronavirus.@CseHuji @HebrewU.
0
5
15
Security researchers protect the general public by disclosure of vulnerabilities. Now: lawsuits to silence security research?.This is very upsetting. cc @IOHK_Charles.
0
4
15
Priceless. McDonnald's branch opens for drive through only due to COVID-19. Kids who live nearby w/o a driver's license get creative to get some burgers.
לפני כמה חודשים נפתח סניף של מקדונלדס בכניסה לקיבוץ עמיעד, אבל מאז בשל הקורונה המקום פעל רק באופן חלקי. בני הנוער מהקיבוץ שכבר נמאס להם לחכות גילו שעכשיו אפשר לקנות רק בדרייב אין אבל רישיון נהיגה ממש אין להם - אז הם מצאו פתרון יצירתי.צילום: יגאל ואורלי שוורץ
0
2
15
Jeff Berwick onstage at the Bitcoin summit argues for financial privacy to stop the tyranny of government, but neglects privacy as a basic human right in other contexts. Everyone ought to care about their data, even if they don't want to do away with governments.
2
2
14
I'm about a month late in discovering this awsome (python oriented) Ethereum development tutorial by @PatrickAlphaC. Highly recommended. He deserves lots of #brownie points (pun intended) for making such a complex topic this accessible.
3
0
13
"Mind the mining" [Goren & Spiegelman]: A paper presented in EC19 predicts that miners turn on and off their machines alternating between difficulty adjustments. A very interesting result! .Paper: Talk:
2
3
14
Bitcoin taxation in Israel is still unclear. We are on the verge of a colossal mistake categorizing Bitcoin as a commodity rather than as a currency. An opinion piece about this (Hebrew):.
1
5
13
@EthereumAddict @realJonaHarris Sorry. We don't have something easily available. There's always this technique:
1
1
12
