What Is the Bitcoin Block Size Limit? – Bitcoin Magazine

Core developers announce new Bitcoin roadmap including a dynamic, fee-based block size limit.

Core developers announce new Bitcoin roadmap including a dynamic, fee-based block size limit. submitted by MrMadden to btc [link] [comments]

“A Transaction Fee Market Exists Without a Block Size Limit”—new research paper ascertains. [Plus earn $10 in bitcoin per typo found in manuscript]

submitted by Peter__R to Bitcoin [link] [comments]

Bitcoin [BTC]: Roger Ver takes another potshot at Bitcoin’s block size limits - AMBCrypto News

Bitcoin [BTC]: Roger Ver takes another potshot at Bitcoin’s block size limits - AMBCrypto News submitted by ulros to fbitcoin [link] [comments]

Bram Cohen "My new invention: Bitcoin++, a hard fork of Bitcoin with one byte added to the block size limit."

Bram Cohen submitted by toddler361 to Bitcoin [link] [comments]

The Lightning Network Could Solve The Bitcoin Block Size Limit - CCN: Financial Bitcoin & Cryptocurrency News

The Lightning Network Could Solve The Bitcoin Block Size Limit - CCN: Financial Bitcoin & Cryptocurrency News submitted by dragger2k to Bitcoin [link] [comments]

News flash: all hard forks and changes in consensus rules so far have been "user activated". Example: when Satoshi added the 1MB block size limit there was no "miner vote", no signalling whatsoever. He just merged the code, users updated and miners followed suit. /r/Bitcoin

News flash: all hard forks and changes in consensus rules so far have been submitted by BitcoinAllBot to BitcoinAll [link] [comments]

A hard fork to increase the block-size limit is the same as creating a new altcoin (bootstrapped on Bitcoin's blockchain), and then just telling everybody to switch to it; it's an idiot's approach to a decentralized system.

Blockstream is working on a more sophisticated approach.
Making a hard fork is the same as creating a new system, and then just telling everyone in the supposedly decentralized system to switch over to the new system; at the very least, verifying nodes must upgrade, and must therefore be subscribed to centralized choreography.
A 2-way peg allows people to switch at any time between 2 systems (i.e., between 2 "hard forks", if you will). If you're going to have a hard fork, the right way is to do it with a 2-way peg, so that people can upgrade or downgrade almost at leisure.
Consider:
So, a hard fork is disastrous, and a soft fork has proven to be dangerous (as it has the potential to devolve into a kind of hard fork, and, at best, reduces security for a time due to increased probability of blockchain reorganization).
The real solution is clear: One and only one more soft fork to allow for 2-way pegs (sidechains); then, there are no more forks of any kind, as all future improvements become a matter of users choosing voluntarily to transfer control of their assets from one system to another. At the very worst, the new system can make a hard fork to copy over the old system's blockchain entirely, begin minting coins itself, and thus leave behind the old system; that kind of hard fork is much less dangerous.
Hard forks are bloody revolution. Sidechains are mild evolution.
submitted by SwagPokerz to Bitcoin [link] [comments]

Bitcoins new block size limit solidifying at 8 megabytes

Bitcoins new block size limit solidifying at 8 megabytes submitted by bravenewcoin to Bitcoin [link] [comments]

Bram Cohen on Twitter: "My new invention: Bitcoin++, a hard fork of Bitcoin with one byte added to the block size limit."

Bram Cohen on Twitter: submitted by themusicgod1 to bitcoin_uncensored [link] [comments]

rbtc objective revealed: new users shouldn't know that a block size limit ever existed. /r/Bitcoin

rbtc objective revealed: new users shouldn't know that a block size limit ever existed. /Bitcoin submitted by BitcoinAllBot to BitcoinAll [link] [comments]

07-13 20:32 - 'rbtc objective revealed: new users shouldn't know that a block size limit ever existed.' (self.Bitcoin) by /u/btwlf removed from /r/Bitcoin within 0-8min

'''
Comment excerpt from jstolfi (confirmed Bitcoin antagonist, very likely rbtc shill) in a long comment thread:
"...today the bitcoin network would be working just as fine as it was working then[...] There would be just one bitcoin reddit forum, no one would know that there was a block size limit, and we would not be having this discussion."
For those who thought this was an honest scaling debate about how/when to increase the blocksize limit... They actually don't want you to know that one ever existed.
Original comment: [link]2
Feel free to read more (or don't). It's just me [arguing with a troll]1 ...
'''
rbtc objective revealed: new users shouldn't know that a block size limit ever existed.
Go1dfish undelete link
unreddit undelete link
Author: btwlf
1: https://xkcd.com/386/ 2: https://www.reddit.com/btc/comments/6ltogq/does_greg_maxwell_have_a_university_degree_in/dk56zpw/
submitted by removalbot to removalbot [link] [comments]

The Lightning Network Could Solve The Bitcoin Block Size Limit - CCN: Financial Bitcoin & Cryptocurrency News

The Lightning Network Could Solve The Bitcoin Block Size Limit - CCN: Financial Bitcoin & Cryptocurrency News submitted by coincrazyy to BitcoinAll [link] [comments]

Bram Cohen "My new invention: Bitcoin++, a hard fork of Bitcoin with one byte added to the block size limit."

Bram Cohen submitted by BitcoinAllBot to BitcoinAll [link] [comments]

New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit | Raystonn . | Jun 08 2015 /r/bitcoin_devlist

New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit | Raystonn . | Jun 08 2015 /bitcoin_devlist submitted by BitcoinAllBot to BitcoinAll [link] [comments]

"A Transaction Fee Market Exists Without a Block Size Limit"--new research paper suggests | Peter R | Aug 04 2015 /r/bitcoin_devlist

submitted by BitcoinAllBot to BitcoinAll [link] [comments]

Bitcoin Fullnode Install Guide for Dummies ;-)

Bitcoin Fullnode Install Guide for Dummies ;-)
Feel free to stop at Level 0 or Level 1, which is fine. More advanced configs are offered to those with more tech savvy. This guide, obviously assumes a Windows 10 install, but other OSes work fine, just find a different guide. BTW, the "For Dummies" is a callback to a set of "tech" books in the 90's intended to be as easy as possible. It is in jest and not intended to insult the reader. Finally, if you dislike the formatting, a well formatted copy can be found here
There is a fairly small subset of Bitcoin users that run a full node. I think the idea of running a full node has gotten a bad rap over the years since there is so much talk about running on a Raspberry Pi, or getting zippy SSDs. Although all of this can be fun, it is often not really required at all. Here are some ways to run a full node starting with the very simple. I'll get into more complex configs, but these are all optional.

Tech Skill Level: 0 (the basics)

  1. Download Bitcoin Core
  2. Launch the downloaded installer and install the app
  3. Launch the installed "Bitcoin Core" app and let it run overnight
In many cases, thats it. If your running a new machine with a fairly good internet connection, 8 or 9 hours will be enough to complete the "Initial Block Download" (IBD). This may fill up your drive a bit, but again, on most new machines, 300 GB of space isn't that hard to come by.

Tech Skill Level: 1 (encrypted wallet)

One thing we left out in the level-0 exercise is encrypting your wallet. It's easy enough to do well, but a bit more difficult to do right. The main challenge is that humans generate really poor passwords. If you want a good password, the best way is to use something called "diceware". Basically, you just grab 4 or 5 dice and each throw of the dice represents a certain word on a special list. The throw {1,4,5,3,1} for example would be the word camping on the EFF-diceware-wordlist. So you repeat this a few times until you have a list of 8 or so words which becomes the passphrase you use to encrypt your wallet. Write it down, it is always hard to remember at first. So at level-1 your list becomes:
  1. Download Bitcoin Core
  2. Launch the downloaded installer and install the app
  3. Launch the installed "Bitcoin Core" app and let it run overnight
  4. Choose Encrypt Wallet from the Settings menu
  5. Enter your 8 word (or so) passphrase generated using the Diceware method

Wallet Encryption Dialog

Tech Skill Level: 2 (enable pruning if needed)

Though I said "300 GB of space isn't hard to come by", some times it actually is. If space is an issue, a simple way to fix it is to tell bitcoin to simple take less space. This is called "pruning" and can take that number from 300 GB down to below 5 GB. If you can't find 5 GB, then you'll have to read ahead to level-4 to add USB storage. But the good news is, enabling pruning is pretty easy, we just add another step to our working list:
  1. Download Bitcoin Core
  2. Launch the downloaded installer and install the app
  3. Launch the installed "Bitcoin Core" app and let it run overnight
  4. Do the wallet encryption steps here if you wish
  5. Choose Options from the Settings menu
  6. Choose Prune block storage to: and select the max size for the blocks to use
  7. Exit and restart the bitcoin application for the changes to take effect

Pruning Dialog
Note, even setting this to 1 GB will still leave you with about a 4.5 GB install. The blocks take up a lot of space, but the chainstate and other folders eat up at least 3.5 GB and they can't be pruned. Also, be aware, to disable pruning requires you to perform the entire IBD again. While pruned some other functions my be disabled as well, so just know that pruning does limit some functionality.

Tech Skill Level: 3 (verify the installer)

Although this is arguably something that should be done at level-0, some find the intricacies of comparing hash (thumbprint) values to be tedious and beyond the scope of a beginner. You will find these types of hash compares suggested quite often as a way to prevent running tainted programs. Programs are often tainted by bad disk or network performance, but most often, taint is malicious code inserted by viruses or malware. This is a way to guard yourself against those types of attacks.
What I cover here is a very basic comparison on the certificate, but a more thorough verification advised by mosts uses a program called Gpg4Win, and is beyond the scope of this beginners guide. But regardless, most users should strive to do this minimum level of validation.
  1. Download Bitcoin Core
  2. Launch the downloaded installer
  3. When prompted "Do you want to allow..." click Show more details
  4. In the details section select Show information about the publisher's certificate
  5. In the certificate window select the Details tab
  6. In the Details tab Subject should start with "CN = Bitcoin Core Code Signing Association"
  7. Ensure Thumbprint in Details reads ea27d3cefb3eb715ed214176a5d027e01ba1ee86
  8. If the checks pass, click OK to exit the certificate window and Yes to allow the installer to run.
  9. Launch the installed "Bitcoin Core" app and let it run overnight
  10. Do the wallet encryption steps here if you wish
  11. Do the optional pruning steps here if you wish

Certification Validation Windows
Note: The certificate used to sign the current Bitcoin installer is only valid from March 2020 to March 2021. After that point the thumbprint on the certificate will change. This is by design and intentional. If your reading this post after March 2021, then it is understood that the thumbprint has changed.

Tech Skill Level: 4 (use secondary storage)

We glossed over the "new machine with fairly good internet" part. Truth be known many people do not have fairly new machines, and find the IBD to take longer than the "over night" best wishes. For most people the slowdown is the disk access when calculating what is called chainstate. This requires fast random reads and writes to the disk. If you have an SSD disk, this will be no problem, but if you have a non-SSD "spinning" disk, random writes are always slow. Though an SSD will speed things up, they are pricey, so a nice middle ground may be a simple high-end USB key drive. You can get some with 10 to 15 MB/s random writes for $20 on Amazon. This is usually a order of magnitude faster than a "spinning" disk. And with pruning (see level-2), a small USB drive should be fine.
Once you decide on a drive, the tricky part will be to enable external storage. It requires editing a configuration file and adding a line. First, we want to create a directory on the key drive. You will need to determine the drive letter of your USB key drive. For the sake of this example, we will assume it is D:, but you must determine this yourself and correct the example. Once you know the drive letter, create a blank folder on the drive called Bitcoin. So for this example, creating Bitcoin on drive D: will create the path D:\Bitcoin. Once done, assuming that D: is your drive, here are the new steps including the edit of the configuration file:
  1. Download Bitcoin Core
  2. Launch the installer, verify it, then run it
  3. Launch the installed "Bitcoin Core" app and let it run overnight
  4. Do the wallet encryption steps here if you wish
  5. Do the optional pruning steps here if you wish
  6. Launch "Notepad" by typing "Notepad.exe" in the windows search bar then click Open
  7. Type the line datadir=D:\Bitcoin (depending on your drive letter) in the blank file
  8. Choose Save from the File menu in notepad
  9. Type %APPDATA%\Bitcoin\bitcoin.conf (note the percent signs) in the File name box
  10. Select All Files from the Save as type dropdown
  11. Click the Save button and overwrite the file if prompted
  12. Exit and restart the bitcoin application for the changes to take effect

Save As Dialog
Now that you've reached this level of technical expertise, there are many new configuration options that you can begin to modify if you wish. Most configuration data is contained in the bitcoin.conf file and learning how to maintain it is a key step for a node operator.

Tech Skill Level: 5 (all other customizations)

Here's a short list of various things you can ADD to your bitcoin.conf file. You generally just add a new line for each configuration settings.
  • addresstype=bech32
  • changetype=bech32
The addresstype / changetype allows your wallet to use the native-segwit (bech32) format. This is the most efficient and inexpensive way to spend bitcoin, and is a recommended configuration. The default uses something called p2sh-segwit which is more compatible with older wallets, but more expensive to spend.
  • minrelaytxfee=0.00000011
Changing the minrelaytxfee setting allows you to help propagate lower fee transactions. It will require more memory but TXN memory is capped at 300 MB by default anyways, so if you have enough memory, it is a good setting to choose.
  • dbcache=2048
The dbcache setting controls how many MB of memory the program will use for the chainstate database. Since this is a key bottleneck in the IBD, setting this value high (2048 MB) will greatly speed up the IBD, assuming you have the memory to spare
  • blocksdir=C:\Bitcoin
  • datadir=D:\Bitcoin
In level-4 we discussed moving the datadir to a fast external storage, but the majority of the space used for bitcoin is the blocks directory (blocksdir). Although you should always use for fastest storage for datadir, you are free to use slow storage for blocksdir. So if you only want to consume a small amount of your SSD (assumed D:) then you can keep your blocks on your slow "spinning" drive.
  • upnp=1
One of the harder challenges you may face running a node, is to get incoming connections. If you are lucky, you may find that your firewall and network HW support the uPnP protocol. If they do, this setting will allow bitcoin to configure uPnP to allow incoming connections to your node. Other methods exist to make your node reachable, but they are well beyond the scope of this guide.
submitted by brianddk to Bitcoin [link] [comments]

Scalenet and Testnet4 are online and open for business

Over the years, some people have made use of testnet3 to test out scaling performance, and have spammed testnet3 with 32 MB blocks. This has caused testnet3 to get kinda bloated; the blockchain now takes an hour or so to sync, which slows down development. Other people have wanted to do stress testing, but have specifically wanted to avoid inconveniencing other people by spamming testnet3, and have therefore not done so. This slows down development too. To address this issue, I created two new networks: testnet4 and scalenet.
Testnet4 is intended to be a low-volume quick-syncing blockchain which is ideal for testing out new transaction formats or applications. It has a 2 MB default block size limit, and comes with aserti3 parameters that make the difficulty recover quickly to CPU-mineable levels. It should remain easy to sync on a low-end VPS or old laptop.
Scalenet is intended to be a high-volume blockchain which is ideal for spamming and stress testing software. It comes with a 256 MB initial default block size limit, and uses aserti3 parameters that make it more suitable for accurately simulating mainnet mining difficulty (though it retains the 20-minute difficulty rule). In order to prevent storage costs from getting unreasonable for a testnet, scalenet will be reset every 6-12 months by invalidating the block at height 10,001 and adding a new checkpoint. Scalenet is intended to be feasible to run on a mid-range desktop computer with some strain.
Testnet4 and scalenet are now online and essentially complete. The code for both has been merged into BCHN and Electron Cash. Testnet4 has also been successfully synced to by Knuth, Bitcoin Unlimited, and libbitcoincashj. Block explorers for both are available, thanks to Axel Gembe (who runs the code) and sickpig (who wrote the code):
http://tbch4.loping.net:3002/
http://sbch.loping.net:3003/
The testnet4 and scalenet MRs were opened on Aug 19th and Aug 27th, and both were merged on Sep 17th. Scalenet reached height 10,000 on October 3rd.
Testnet4 and Scalenet support are present in the master branch of BCHN, and will be included in the next release of BCHN. Some other software (e.g. Electron Cash) already has support in their latest release, but most is still pending.
See also: https://bitcoincashresearch.org/t/testnet4-and-scalenet/148/7
submitted by jtoomim to btc [link] [comments]

Gridcoin 5.0.0.0-Mandatory "Fern" Release

https://github.com/gridcoin-community/Gridcoin-Research/releases/tag/5.0.0.0
Finally! After over ten months of development and testing, "Fern" has arrived! This is a whopper. 240 pull requests merged. Essentially a complete rewrite that was started with the scraper (the "neural net" rewrite) in "Denise" has now been completed. Practically the ENTIRE Gridcoin specific codebase resting on top of the vanilla Bitcoin/Peercoin/Blackcoin vanilla PoS code has been rewritten. This removes the team requirement at last (see below), although there are many other important improvements besides that.
Fern was a monumental undertaking. We had to encode all of the old rules active for the v10 block protocol in new code and ensure that the new code was 100% compatible. This had to be done in such a way as to clear out all of the old spaghetti and ring-fence it with tightly controlled class implementations. We then wrote an entirely new, simplified ruleset for research rewards and reengineered contracts (which includes beacon management, polls, and voting) using properly classed code. The fundamentals of Gridcoin with this release are now on a very sound and maintainable footing, and the developers believe the codebase as updated here will serve as the fundamental basis for Gridcoin's future roadmap.
We have been testing this for MONTHS on testnet in various stages. The v10 (legacy) compatibility code has been running on testnet continuously as it was developed to ensure compatibility with existing nodes. During the last few months, we have done two private testnet forks and then the full public testnet testing for v11 code (the new protocol which is what Fern implements). The developers have also been running non-staking "sentinel" nodes on mainnet with this code to verify that the consensus rules are problem-free for the legacy compatibility code on the broader mainnet. We believe this amount of testing is going to result in a smooth rollout.
Given the amount of changes in Fern, I am presenting TWO changelogs below. One is high level, which summarizes the most significant changes in the protocol. The second changelog is the detailed one in the usual format, and gives you an inkling of the size of this release.

Highlights

Protocol

Note that the protocol changes will not become active until we cross the hard-fork transition height to v11, which has been set at 2053000. Given current average block spacing, this should happen around October 4, about one month from now.
Note that to get all of the beacons in the network on the new protocol, we are requiring ALL beacons to be validated. A two week (14 day) grace period is provided by the code, starting at the time of the transition height, for people currently holding a beacon to validate the beacon and prevent it from expiring. That means that EVERY CRUNCHER must advertise and validate their beacon AFTER the v11 transition (around Oct 4th) and BEFORE October 18th (or more precisely, 14 days from the actual date of the v11 transition). If you do not advertise and validate your beacon by this time, your beacon will expire and you will stop earning research rewards until you advertise and validate a new beacon. This process has been made much easier by a brand new beacon "wizard" that helps manage beacon advertisements and renewals. Once a beacon has been validated and is a v11 protocol beacon, the normal 180 day expiration rules apply. Note, however, that the 180 day expiration on research rewards has been removed with the Fern update. This means that while your beacon might expire after 180 days, your earned research rewards will be retained and can be claimed by advertising a beacon with the same CPID and going through the validation process again. In other words, you do not lose any earned research rewards if you do not stake a block within 180 days and keep your beacon up-to-date.
The transition height is also when the team requirement will be relaxed for the network.

GUI

Besides the beacon wizard, there are a number of improvements to the GUI, including new UI transaction types (and icons) for staking the superblock, sidestake sends, beacon advertisement, voting, poll creation, and transactions with a message. The main screen has been revamped with a better summary section, and better status icons. Several changes under the hood have improved GUI performance. And finally, the diagnostics have been revamped.

Blockchain

The wallet sync speed has been DRASTICALLY improved. A decent machine with a good network connection should be able to sync the entire mainnet blockchain in less than 4 hours. A fast machine with a really fast network connection and a good SSD can do it in about 2.5 hours. One of our goals was to reduce or eliminate the reliance on snapshots for mainnet, and I think we have accomplished that goal with the new sync speed. We have also streamlined the in-memory structures for the blockchain which shaves some memory use.
There are so many goodies here it is hard to summarize them all.
I would like to thank all of the contributors to this release, but especially thank @cyrossignol, whose incredible contributions formed the backbone of this release. I would also like to pay special thanks to @barton2526, @caraka, and @Quezacoatl1, who tirelessly helped during the testing and polishing phase on testnet with testing and repeated builds for all architectures.
The developers are proud to present this release to the community and we believe this represents the starting point for a true renaissance for Gridcoin!

Summary Changelog

Accrual

Changed

Most significantly, nodes calculate research rewards directly from the magnitudes in EACH superblock between stakes instead of using a two- or three- point average based on a CPID's current magnitude and the magnitude for the CPID when it last staked. For those long-timers in the community, this has been referred to as "Superblock Windows," and was first done in proof-of-concept form by @denravonska.

Removed

Beacons

Added

Changed

Removed

Unaltered

As a reminder:

Superblocks

Added

Changed

Removed

Voting

Added

Changed

Removed

Detailed Changelog

[5.0.0.0] 2020-09-03, mandatory, "Fern"

Added

Changed

Removed

Fixed

submitted by jamescowens to gridcoin [link] [comments]

Technical: The Path to Taproot Activation

Taproot! Everybody wants to have it, somebody wants to make it, nobody knows how to get it!
(If you are asking why everybody wants it, see: Technical: Taproot: Why Activate?)
(Pedants: I mostly elide over lockin times)
Briefly, Taproot is that neat new thing that gets us:
So yes, let's activate taproot!

The SegWit Wars

The biggest problem with activating Taproot is PTSD from the previous softfork, SegWit. Pieter Wuille, one of the authors of the current Taproot proposal, has consistently held the position that he will not discuss activation, and will accept whatever activation process is imposed on Taproot. Other developers have expressed similar opinions.
So what happened with SegWit activation that was so traumatic? SegWit used the BIP9 activation method. Let's dive into BIP9!

BIP9 Miner-Activated Soft Fork

Basically, BIP9 has a bunch of parameters:
Now there are other parameters (name, starttime) but they are not anywhere near as important as the above two.
A number that is not a parameter, is 95%. Basically, activation of a BIP9 softfork is considered as actually succeeding if at least 95% of blocks in the last 2 weeks had the specified bit in the nVersion set. If less than 95% had this bit set before the timeout, then the upgrade fails and never goes into the network. This is not a parameter: it is a constant defined by BIP9, and developers using BIP9 activation cannot change this.
So, first some simple questions and their answers:

The Great Battles of the SegWit Wars

SegWit not only fixed transaction malleability, it also created a practical softforkable blocksize increase that also rebalanced weights so that the cost of spending a UTXO is about the same as the cost of creating UTXOs (and spending UTXOs is "better" since it limits the size of the UTXO set that every fullnode has to maintain).
So SegWit was written, the activation was decided to be BIP9, and then.... miner signalling stalled at below 75%.
Thus were the Great SegWit Wars started.

BIP9 Feature Hostage

If you are a miner with at least 5% global hashpower, you can hold a BIP9-activated softfork hostage.
You might even secretly want the softfork to actually push through. But you might want to extract concession from the users and the developers. Like removing the halvening. Or raising or even removing the block size caps (which helps larger miners more than smaller miners, making it easier to become a bigger fish that eats all the smaller fishes). Or whatever.
With BIP9, you can hold the softfork hostage. You just hold out and refuse to signal. You tell everyone you will signal, if and only if certain concessions are given to you.
This ability by miners to hold a feature hostage was enabled because of the miner-exit allowed by the timeout on BIP9. Prior to that, miners were considered little more than expendable security guards, paid for the risk they take to secure the network, but not special in the grand scheme of Bitcoin.

Covert ASICBoost

ASICBoost was a novel way of optimizing SHA256 mining, by taking advantage of the structure of the 80-byte header that is hashed in order to perform proof-of-work. The details of ASICBoost are out-of-scope here but you can read about it elsewhere
Here is a short summary of the two types of ASICBoost, relevant to the activation discussion.
Now, "overt" means "obvious", while "covert" means hidden. Overt ASICBoost is obvious because nVersion bits that are not currently in use for BIP9 activations are usually 0 by default, so setting those bits to 1 makes it obvious that you are doing something weird (namely, Overt ASICBoost). Covert ASICBoost is non-obvious because the order of transactions in a block are up to the miner anyway, so the miner rearranging the transactions in order to get lower power consumption is not going to be detected.
Unfortunately, while Overt ASICBoost was compatible with SegWit, Covert ASICBoost was not. This is because, pre-SegWit, only the block header Merkle tree committed to the transaction ordering. However, with SegWit, another Merkle tree exists, which commits to transaction ordering as well. Covert ASICBoost would require more computation to manipulate two Merkle trees, obviating the power benefits of Covert ASICBoost anyway.
Now, miners want to use ASICBoost (indeed, about 60->70% of current miners probably use the Overt ASICBoost nowadays; if you have a Bitcoin fullnode running you will see the logs with lots of "60 of last 100 blocks had unexpected versions" which is exactly what you would see with the nVersion manipulation that Overt ASICBoost does). But remember: ASICBoost was, at around the time, a novel improvement. Not all miners had ASICBoost hardware. Those who did, did not want it known that they had ASICBoost hardware, and wanted to do Covert ASICBoost!
But Covert ASICBoost is incompatible with SegWit, because SegWit actually has two Merkle trees of transaction data, and Covert ASICBoost works by fudging around with transaction ordering in a block, and recomputing two Merkle Trees is more expensive than recomputing just one (and loses the ASICBoost advantage).
Of course, those miners that wanted Covert ASICBoost did not want to openly admit that they had ASICBoost hardware, they wanted to keep their advantage secret because miners are strongly competitive in a very tight market. And doing ASICBoost Covertly was just the ticket, but they could not work post-SegWit.
Fortunately, due to the BIP9 activation process, they could hold SegWit hostage while covertly taking advantage of Covert ASICBoost!

UASF: BIP148 and BIP8

When the incompatibility between Covert ASICBoost and SegWit was realized, still, activation of SegWit stalled, and miners were still not openly claiming that ASICBoost was related to non-activation of SegWit.
Eventually, a new proposal was created: BIP148. With this rule, 3 months before the end of the SegWit timeout, nodes would reject blocks that did not signal SegWit. Thus, 3 months before SegWit timeout, BIP148 would force activation of SegWit.
This proposal was not accepted by Bitcoin Core, due to the shortening of the timeout (it effectively times out 3 months before the initial SegWit timeout). Instead, a fork of Bitcoin Core was created which added the patch to comply with BIP148. This was claimed as a User Activated Soft Fork, UASF, since users could freely download the alternate fork rather than sticking with the developers of Bitcoin Core.
Now, BIP148 effectively is just a BIP9 activation, except at its (earlier) timeout, the new rules would be activated anyway (instead of the BIP9-mandated behavior that the upgrade is cancelled at the end of the timeout).
BIP148 was actually inspired by the BIP8 proposal (the link here is a historical version; BIP8 has been updated recently, precisely in preparation for Taproot activation). BIP8 is basically BIP9, but at the end of timeout, the softfork is activated anyway rather than cancelled.
This removed the ability of miners to hold the softfork hostage. At best, they can delay the activation, but not stop it entirely by holding out as in BIP9.
Of course, this implies risk that not all miners have upgraded before activation, leading to possible losses for SPV users, as well as again re-pressuring miners to signal activation, possibly without the miners actually upgrading their software to properly impose the new softfork rules.

BIP91, SegWit2X, and The Aftermath

BIP148 inspired countermeasures, possibly from the Covert ASiCBoost miners, possibly from concerned users who wanted to offer concessions to miners. To this day, the common name for BIP148 - UASF - remains an emotionally-charged rallying cry for parts of the Bitcoin community.
One of these was SegWit2X. This was brokered in a deal between some Bitcoin personalities at a conference in New York, and thus part of the so-called "New York Agreement" or NYA, another emotionally-charged acronym.
The text of the NYA was basically:
  1. Set up a new activation threshold at 80% signalled at bit 4 (vs bit 1 for SegWit).
    • When this 80% signalling was reached, miners would require that bit 1 for SegWit be signalled to achive the 95% activation needed for SegWit.
  2. If the bit 4 signalling reached 80%, increase the block weight limit from the SegWit 4000000 to the SegWit2X 8000000, 6 months after bit 1 activation.
The first item above was coded in BIP91.
Unfortunately, if you read the BIP91, independently of NYA, you might come to the conclusion that BIP91 was only about lowering the threshold to 80%. In particular, BIP91 never mentions anything about the second point above, it never mentions that bit 4 80% threshold would also signal for a later hardfork increase in weight limit.
Because of this, even though there are claims that NYA (SegWit2X) reached 80% dominance, a close reading of BIP91 shows that the 80% dominance was only for SegWit activation, without necessarily a later 2x capacity hardfork (SegWit2X).
This ambiguity of bit 4 (NYA says it includes a 2x capacity hardfork, BIP91 says it does not) has continued to be a thorn in blocksize debates later. Economically speaking, Bitcoin futures between SegWit and SegWit2X showed strong economic dominance in favor of SegWit (SegWit2X futures were traded at a fraction in value of SegWit futures: I personally made a tidy but small amount of money betting against SegWit2X in the futures market), so suggesting that NYA achieved 80% dominance even in mining is laughable, but the NYA text that ties bit 4 to SegWit2X still exists.
Historically, BIP91 triggered which caused SegWit to activate before the BIP148 shorter timeout. BIP148 proponents continue to hold this day that it was the BIP148 shorter timeout and no-compromises-activate-on-August-1 that made miners flock to BIP91 as a face-saving tactic that actually removed the second clause of NYA. NYA supporters keep pointing to the bit 4 text in the NYA and the historical activation of BIP91 as a failed promise by Bitcoin developers.

Taproot Activation Proposals

There are two primary proposals I can see for Taproot activation:
  1. BIP8.
  2. Modern Softfork Activation.
We have discussed BIP8: roughly, it has bit and timeout, if 95% of miners signal bit it activates, at the end of timeout it activates. (EDIT: BIP8 has had recent updates: at the end of timeout it can now activate or fail. For the most part, in the below text "BIP8", means BIP8-and-activate-at-timeout, and "BIP9" means BIP8-and-fail-at-timeout)
So let's take a look at Modern Softfork Activation!

Modern Softfork Activation

This is a more complex activation method, composed of BIP9 and BIP8 as supcomponents.
  1. First have a 12-month BIP9 (fail at timeout).
  2. If the above fails to activate, have a 6-month discussion period during which users and developers and miners discuss whether to continue to step 3.
  3. Have a 24-month BIP8 (activate at timeout).
The total above is 42 months, if you are counting: 3.5 years worst-case activation.
The logic here is that if there are no problems, BIP9 will work just fine anyway. And if there are problems, the 6-month period should weed it out. Finally, miners cannot hold the feature hostage since the 24-month BIP8 period will exist anyway.

PSA: Being Resilient to Upgrades

Software is very birttle.
Anyone who has been using software for a long time has experienced something like this:
  1. You hear a new version of your favorite software has a nice new feature.
  2. Excited, you install the new version.
  3. You find that the new version has subtle incompatibilities with your current workflow.
  4. You are sad and downgrade to the older version.
  5. You find out that the new version has changed your files in incompatible ways that the old version cannot work with anymore.
  6. You tearfully reinstall the newer version and figure out how to get your lost productivity now that you have to adapt to a new workflow
If you are a technically-competent user, you might codify your workflow into a bunch of programs. And then you upgrade one of the external pieces of software you are using, and find that it has a subtle incompatibility with your current workflow which is based on a bunch of simple programs you wrote yourself. And if those simple programs are used as the basis of some important production system, you hve just screwed up because you upgraded software on an important production system.
And well, one of the issues with new softfork activation is that if not enough people (users and miners) upgrade to the newest Bitcoin software, the security of the new softfork rules are at risk.
Upgrading software of any kind is always a risk, and the more software you build on top of the software-being-upgraded, the greater you risk your tower of software collapsing while you change its foundations.
So if you have some complex Bitcoin-manipulating system with Bitcoin somewhere at the foundations, consider running two Bitcoin nodes:
  1. One is a "stable-version" Bitcoin node. Once it has synced, set it up to connect=x.x.x.x to the second node below (so that your ISP bandwidth is only spent on the second node). Use this node to run all your software: it's a stable version that you don't change for long periods of time. Enable txiindex, disable pruning, whatever your software needs.
  2. The other is an "always-up-to-date" Bitcoin Node. Keep its stoarge down with pruning (initially sync it off the "stable-version" node). You can't use blocksonly if your "stable-version" node needs to send transactions, but otherwise this "always-up-to-date" Bitcoin node can be kept as a low-resource node, so you can run both nodes in the same machine.
When a new Bitcoin version comes up, you just upgrade the "always-up-to-date" Bitcoin node. This protects you if a future softfork activates, you will only receive valid Bitcoin blocks and transactions. Since this node has nothing running on top of it, it is just a special peer of the "stable-version" node, any software incompatibilities with your system software do not exist.
Your "stable-version" Bitcoin node remains the same version until you are ready to actually upgrade this node and are prepared to rewrite most of the software you have running on top of it due to version compatibility problems.
When upgrading the "always-up-to-date", you can bring it down safely and then start it later. Your "stable-version" wil keep running, disconnected from the network, but otherwise still available for whatever queries. You do need some system to stop the "always-up-to-date" node if for any reason the "stable-version" goes down (otherwisee if the "always-up-to-date" advances its pruning window past what your "stable-version" has, the "stable-version" cannot sync afterwards), but if you are technically competent enough that you need to do this, you are technically competent enough to write such a trivial monitor program (EDIT: gmax notes you can adjust the pruning window by RPC commands to help with this as well).
This recommendation is from gmaxwell on IRC, by the way.
submitted by almkglor to Bitcoin [link] [comments]

Ethereum centralization concerns

Apologies if this has been addressed elsewhere, or if the information I'm responding to here is out of date.
tldr: Are Ethereum (full, validating) nodes incentivized to vote no on gas limit increases that would lead to centralization?
Context:
I just read this old post, its follow up post, and this response post all discussing whether or not Ethereum will trend towards centralization over time. As far as I can tell, all of that long discussion really boils down to disagreements about this paragraph from Gustav's post:

As miners are incentivized to act in ways that maximize the value of the tokens they receive in each mined block, they are unlikely to vote for a blocksize increase that would break the network. If the author trusts Bitcoin miners to act in ways that maximize the value of their bitcoins (such as not censoring transactions, generally prioritizing txs by their fee and otherwise act in ways that are beneficial for the network) the author should trust Ethereum miners to only vote for block sizes that can be handled by reasonable hardware, as the decentralized verification done by full nodes underpins the security of the network.
StopAndDecrypt replies:
The network doesn’t break because validators drop off and peers are lost. The network functions with two datacenters. What breaks is decentralization. The connected nodes have no incentive to care about other less-connected nodes validation abilities.
[...]
Vitalik even agreed that [the number of full validating nodes] would shrink over time if the gas limits kept going up, and there’s nothing stopping that from happening. Right now miners are being altruistic, but what happens when mining doesn’t even exist? What happens when it’s just staking and the people doing it don’t care about other people’s blocks getting orphaned? Why would they keep the gas limit down? Remember they can manually adjust this, so why would they intentionally keep it low if they’re hyper-connected to each other and fully capable of processing that data? What happens when they start compounding their staking earnings, setting up more nodes, and gain more control of the network?
Summary:
As block sizes increase, the number of full validating nodes decreases. Bitcoin solves this by simply saying block sizes never go up, period, and if that limits the amount of TPS the L1 layer can handle, so be it; just scale on L2. Ethereum's answer according to Vitalik is the gas price limits (and indirectly through that block size limits) that each individual minevalidator enforces. Implicit in this I believe is that sooner or later the block size limit has to stop growing (approximating the bitcoin approach), at least until hardware costs drop enough. This relies on an incentive mechanism in place to prevent validators from constantly increasing gas limits per block and letting the network trend towards centralization. Without such an incentive mechanism, I'd think each individual validator wouldn't necessarily care if increasing block sizes caused other validators to drop off the network, so long as they are able to keep up, which does indeed seem like it would eventually lead to a small number of powerful validators controlling the base layer.
Core issue and my actual question:
So I think the real question at the core of this disagreement is: in what cases would (full, validating) nodes reject a block due to it being too big (using too much gas)? What are the incentive mechanisms that keep individual validators aligned with the goal of keeping the core validator pool decentralized?
Please note I'm only talking about the centralization of fully validating nodes with the power to reject new blocks, light clients don't help, and sharding helps by a constant factor in the short term but doesn't address the fundamental long term trends. PoW vs PoS is orthogonal and doesn't really affect the issues being discussed here .
Thanks!
submitted by stbrody to ethereum [link] [comments]

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submitted by curtiyolma to u/curtiyolma [link] [comments]

Scaling Reddit Community Points with Arbitrum Rollup: a piece of cake

Scaling Reddit Community Points with Arbitrum Rollup: a piece of cake
https://preview.redd.it/b80c05tnb9e51.jpg?width=2550&format=pjpg&auto=webp&s=850282c1a3962466ed44f73886dae1c8872d0f31
Submitted for consideration to The Great Reddit Scaling Bake-Off
Baked by the pastry chefs at Offchain Labs
Please send questions or comments to [[email protected] ](mailto:[email protected])
1. Overview
We're excited to submit Arbitrum Rollup for consideration to The Great Reddit Scaling Bake-Off. Arbitrum Rollup is the only Ethereum scaling solution that supports arbitrary smart contracts without compromising on Ethereum's security or adding points of centralization. For Reddit, this means that Arbitrum can not only scale the minting and transfer of Community Points, but it can foster a creative ecosystem built around Reddit Community Points enabling points to be used in a wide variety of third party applications. That's right -- you can have your cake and eat it too!
Arbitrum Rollup isn't just Ethereum-style. Its Layer 2 transactions are byte-for-byte identical to Ethereum, which means Ethereum users can continue to use their existing addresses and wallets, and Ethereum developers can continue to use their favorite toolchains and development environments out-of-the-box with Arbitrum. Coupling Arbitrum’s tooling-compatibility with its trustless asset interoperability, Reddit not only can scale but can onboard the entire Ethereum community at no cost by giving them the same experience they already know and love (well, certainly know).
To benchmark how Arbitrum can scale Reddit Community Points, we launched the Reddit contracts on an Arbitrum Rollup chain. Since Arbitrum provides full Solidity support, we didn't have to rewrite the Reddit contracts or try to mimic their functionality using an unfamiliar paradigm. Nope, none of that. We launched the Reddit contracts unmodified on Arbitrum Rollup complete with support for minting and distributing points. Like every Arbitrum Rollup chain, the chain included a bridge interface in which users can transfer Community Points or any other asset between the L1 and L2 chains. Arbitrum Rollup chains also support dynamic contract loading, which would allow third-party developers to launch custom ecosystem apps that integrate with Community Points on the very same chain that runs the Reddit contracts.
1.1 Why Ethereum
Perhaps the most exciting benefit of distributing Community Points using a blockchain is the ability to seamlessly port points to other applications and use them in a wide variety of contexts. Applications may include simple transfers such as a restaurant that allows Redditors to spend points on drinks. Or it may include complex smart contracts -- such as placing Community Points as a wager for a multiparty game or as collateral in a financial contract.
The common denominator between all of the fun uses of Reddit points is that it needs a thriving ecosystem of both users and developers, and the Ethereum blockchain is perhaps the only smart contract platform with significant adoption today. While many Layer 1 blockchains boast lower cost or higher throughput than the Ethereum blockchain, more often than not, these attributes mask the reality of little usage, weaker security, or both.
Perhaps another platform with significant usage will rise in the future. But today, Ethereum captures the mindshare of the blockchain community, and for Community Points to provide the most utility, the Ethereum blockchain is the natural choice.
1.2 Why Arbitrum
While Ethereum's ecosystem is unmatched, the reality is that fees are high and capacity is too low to support the scale of Reddit Community Points. Enter Arbitrum. Arbitrum Rollup provides all of the ecosystem benefits of Ethereum, but with orders of magnitude more capacity and at a fraction of the cost of native Ethereum smart contracts. And most of all, we don't change the experience from users. They continue to use the same wallets, addresses, languages, and tools.
Arbitrum Rollup is not the only solution that can scale payments, but it is the only developed solution that can scale both payments and arbitrary smart contracts trustlessly, which means that third party users can build highly scalable add-on apps that can be used without withdrawing money from the Rollup chain. If you believe that Reddit users will want to use their Community Points in smart contracts--and we believe they will--then it makes the most sense to choose a single scaling solution that can support the entire ecosystem, eliminating friction for users.
We view being able to run smart contracts in the same scaling solution as fundamentally critical since if there's significant demand in running smart contracts from Reddit's ecosystem, this would be a load on Ethereum and would itself require a scaling solution. Moreover, having different scaling solutions for the minting/distribution/spending of points and for third party apps would be burdensome for users as they'd have to constantly shuffle their Points back and forth.
2. Arbitrum at a glance
Arbitrum Rollup has a unique value proposition as it offers a combination of features that no other scaling solution achieves. Here we highlight its core attributes.
Decentralized. Arbitrum Rollup is as decentralized as Ethereum. Unlike some other Layer 2 scaling projects, Arbitrum Rollup doesn't have any centralized components or centralized operators who can censor users or delay transactions. Even in non-custodial systems, centralized components provide a risk as the operators are generally incentivized to increase their profit by extracting rent from users often in ways that severely degrade user experience. Even if centralized operators are altruistic, centralized components are subject to hacking, coercion, and potential liability.
Massive Scaling. Arbitrum achieves order of magnitude scaling over Ethereum's L1 smart contracts. Our software currently supports 453 transactions-per-second for basic transactions (at 1616 Ethereum gas per tx). We have a lot of room left to optimize (e.g. aggregating signatures), and over the next several months capacity will increase significantly. As described in detail below, Arbitrum can easily support and surpass Reddit's anticipated initial load, and its capacity will continue to improve as Reddit's capacity needs grow.
Low cost. The cost of running Arbitrum Rollup is quite low compared to L1 Ethereum and other scaling solutions such as those based on zero-knowledge proofs. Layer 2 fees are low, fixed, and predictable and should not be overly burdensome for Reddit to cover. Nobody needs to use special equipment or high-end machines. Arbitrum requires validators, which is a permissionless role that can be run on any reasonable on-line machine. Although anybody can act as a validator, in order to protect against a “tragedy of the commons” and make sure reputable validators are participating, we support a notion of “invited validators” that are compensated for their costs. In general, users pay (low) fees to cover the invited validators’ costs, but we imagine that Reddit may cover this cost for its users. See more on the costs and validator options below.
Ethereum Developer Experience. Not only does Arbitrum support EVM smart contracts, but the developer experience is identical to that of L1 Ethereum contracts and fully compatible with Ethereum tooling. Developers can port existing Solidity apps or write new ones using their favorite and familiar toolchains (e.g. Truffle, Buidler). There are no new languages or coding paradigms to learn.
Ethereum wallet compatibility. Just as in Ethereum, Arbitrum users need only hold keys, but do not have to store any coin history or additional data to protect or access their funds. Since Arbitrum transactions are semantically identical to Ethereum L1 transactions, existing Ethereum users can use their existing Ethereum keys with their existing wallet software such as Metamask.
Token interoperability. Users can easily transfer their ETH, ERC-20 and ERC-721 tokens between Ethereum and the Arbitrum Rollup chain. As we explain in detail below, it is possible to mint tokens in L2 that can subsequently be withdrawn and recognized by the L1 token contract.
Fast finality. Transactions complete with the same finality time as Ethereum L1 (and it's possible to get faster finality guarantees by trading away trust assumptions; see the Arbitrum Rollup whitepaper for details).
Non-custodial. Arbitrum Rollup is a non-custodial scaling solution, so users control their funds/points and neither Reddit nor anyone else can ever access or revoke points held by users.
Censorship Resistant. Since it's completely decentralized, and the Arbitrum protocol guarantees progress trustlessly, Arbitrum Rollup is just as censorship-proof as Ethereum.
Block explorer. The Arbitrum Rollup block explorer allows users to view and analyze transactions on the Rollup chain.
Limitations
Although this is a bake-off, we're not going to sugar coat anything. Arbitrum Rollup, like any Optimistic Rollup protocol, does have one limitation, and that's the delay on withdrawals.
As for the concrete length of the delay, we've done a good deal of internal modeling and have blogged about this as well. Our current modeling suggests a 3-hour delay is sufficient (but as discussed in the linked post there is a tradeoff space between the length of the challenge period and the size of the validators’ deposit).
Note that this doesn't mean that the chain is delayed for three hours. Arbitrum Rollup supports pipelining of execution, which means that validators can keep building new states even while previous ones are “in the pipeline” for confirmation. As the challenge delays expire for each update, a new state will be confirmed (read more about this here).
So activity and progress on the chain are not delayed by the challenge period. The only thing that's delayed is the consummation of withdrawals. Recall though that any single honest validator knows immediately (at the speed of L1 finality) which state updates are correct and can guarantee that they will eventually be confirmed, so once a valid withdrawal has been requested on-chain, every honest party knows that the withdrawal will definitely happen. There's a natural place here for a liquidity market in which a validator (or someone who trusts a validator) can provide withdrawal loans for a small interest fee. This is a no-risk business for them as they know which withdrawals will be confirmed (and can force their confirmation trustlessly no matter what anyone else does) but are just waiting for on-chain finality.
3. The recipe: How Arbitrum Rollup works
For a description of the technical components of Arbitrum Rollup and how they interact to create a highly scalable protocol with a developer experience that is identical to Ethereum, please refer to the following documents:
Arbitrum Rollup Whitepaper
Arbitrum academic paper (describes a previous version of Arbitrum)
4. Developer docs and APIs
For full details about how to set up and interact with an Arbitrum Rollup chain or validator, please refer to our developer docs, which can be found at https://developer.offchainlabs.com/.
Note that the Arbitrum version described on that site is older and will soon be replaced by the version we are entering in Reddit Bake-Off, which is still undergoing internal testing before public release.
5. Who are the validators?
As with any Layer 2 protocol, advancing the protocol correctly requires at least one validator (sometimes called block producers) that is honest and available. A natural question is: who are the validators?
Recall that the validator set for an Arbitrum chain is open and permissionless; anyone can start or stop validating at will. (A useful analogy is to full nodes on an L1 chain.) But we understand that even though anyone can participate, Reddit may want to guarantee that highly reputable nodes are validating their chain. Reddit may choose to validate the chain themselves and/or hire third-party validators.To this end, we have begun building a marketplace for validator-for-hire services so that dapp developers can outsource validation services to reputable nodes with high up-time. We've announced a partnership in which Chainlink nodes will provide Arbitrum validation services, and we expect to announce more partnerships shortly with other blockchain infrastructure providers.
Although there is no requirement that validators are paid, Arbitrum’s economic model tracks validators’ costs (e.g. amount of computation and storage) and can charge small fees on user transactions, using a gas-type system, to cover those costs. Alternatively, a single party such as Reddit can agree to cover the costs of invited validators.
6. Reddit Contract Support
Since Arbitrum contracts and transactions are byte-for-byte compatible with Ethereum, supporting the Reddit contracts is as simple as launching them on an Arbitrum chain.
Minting. Arbitrum Rollup supports hybrid L1/L2 tokens which can be minted in L2 and then withdrawn onto the L1. An L1 contract at address A can make a special call to the EthBridge which deploys a "buddy contract" to the same address A on an Arbitrum chain. Since it's deployed at the same address, users can know that the L2 contract is the authorized "buddy" of the L1 contract on the Arbitrum chain.
For minting, the L1 contract is a standard ERC-20 contract which mints and burns tokens when requested by the L2 contract. It is paired with an ERC-20 contract in L2 which mints tokens based on whatever programmer provided minting facility is desired and burns tokens when they are withdrawn from the rollup chain. Given this base infrastructure, Arbitrum can support any smart contract based method for minting tokens in L2, and indeed we directly support Reddit's signature/claim based minting in L2.
Batch minting. What's better than a mint cookie? A whole batch! In addition to supporting Reddit’s current minting/claiming scheme, we built a second minting design, which we believe outperforms the signature/claim system in many scenarios.
In the current system, Reddit periodically issues signed statements to users, who then take those statements to the blockchain to claim their tokens. An alternative approach would have Reddit directly submit the list of users/amounts to the blockchain and distribute the tokens to the users without the signature/claim process.
To optimize the cost efficiency of this approach, we designed an application-specific compression scheme to minimize the size of the batch distribution list. We analyzed the data from Reddit's previous distributions and found that the data is highly compressible since token amounts are small and repeated, and addresses appear multiple times. Our function groups transactions by size, and replaces previously-seen addresses with a shorter index value. We wrote client code to compress the data, wrote a Solidity decompressing function, and integrated that function into Reddit’s contract running on Arbitrum.
When we ran the compression function on the previous Reddit distribution data, we found that we could compress batched minting data down to to 11.8 bytes per minting event (averaged over a 6-month trace of Reddit’s historical token grants)compared with roughly 174 bytes of on-chain data needed for the signature claim approach to minting (roughly 43 for an RLP-encoded null transaction + 65 for Reddit's signature + 65 for the user's signature + roughly 8 for the number of Points) .
The relative benefit of the two approaches with respect to on-chain call data cost depends on the percentage of users that will actually claim their tokens on chain. With the above figures, batch minting will be cheaper if roughly 5% of users redeem their claims. We stress that our compression scheme is not Arbitrum-specific and would be beneficial in any general-purpose smart contract platform.
8. Benchmarks and costs
In this section, we give the full costs of operating the Reddit contracts on an Arbitrum Rollup chain including the L1 gas costs for the Rollup chain, the costs of computation and storage for the L2 validators as well as the capital lockup requirements for staking.
Arbitrum Rollup is still on testnet, so we did not run mainnet benchmarks. Instead, we measured the L1 gas cost and L2 workload for Reddit operations on Arbitrum and calculated the total cost assuming current Ethereum gas prices. As noted below in detail, our measurements do not assume that Arbitrum is consuming the entire capacity of Ethereum. We will present the details of our model now, but for full transparency you can also play around with it yourself and adjust the parameters, by copying the spreadsheet found here.
Our cost model is based on measurements of Reddit’s contracts, running unmodified (except for the addition of a batch minting function) on Arbitrum Rollup on top of Ethereum.
On the distribution of transactions and frequency of assertions. Reddit's instructions specify the following minimum parameters that submissions should support:
Over a 5 day period, your scaling PoC should be able to handle:
  • 100,000 point claims (minting & distributing points)
  • 25,000 subscriptions
  • 75,000 one-off points burning
  • 100,000 transfers
We provide the full costs of operating an Arbitrum Rollup chain with this usage under the assumption that tokens are minted or granted to users in batches, but other transactions are uniformly distributed over the 5 day period. Unlike some other submissions, we do not make unrealistic assumptions that all operations can be submitted in enormous batches. We assume that batch minting is done in batches that use only a few percent on an L1 block’s gas, and that other operations come in evenly over time and are submitted in batches, with one batch every five minutes to keep latency reasonable. (Users are probably already waiting for L1 finality, which takes at least that long to achieve.)
We note that assuming that there are only 300,000 transactions that arrive uniformly over the 5 day period will make our benchmark numbers lower, but we believe that this will reflect the true cost of running the system. To see why, say that batches are submitted every five minutes (20 L1 blocks) and there's a fixed overhead of c bytes of calldata per batch, the cost of which will get amortized over all transactions executed in that batch. Assume that each individual transaction adds a marginal cost of t. Lastly assume the capacity of the scaling system is high enough that it can support all of Reddit's 300,000 transactions within a single 20-block batch (i.e. that there is more than c + 300,000*t byes of calldata available in 20 blocks).
Consider what happens if c, the per-batch overhead, is large (which it is in some systems, but not in Arbitrum). In the scenario that transactions actually arrive at the system's capacity and each batch is full, then c gets amortized over 300,000 transactions. But if we assume that the system is not running at capacity--and only receives 300,000 transactions arriving uniformly over 5 days-- then each 20-block assertion will contain about 200 transactions, and thus each transaction will pay a nontrivial cost due to c.
We are aware that other proposals presented scaling numbers assuming that 300,000 transactions arrived at maximum capacity and was executed in a single mega-transaction, but according to our estimates, for at least one such report, this led to a reported gas price that was 2-3 orders of magnitude lower than it would have been assuming uniform arrival. We make more realistic batching assumptions, and we believe Arbitrum compares well when batch sizes are realistic.
Our model. Our cost model includes several sources of cost:
  • L1 gas costs: This is the cost of posting transactions as calldata on the L1 chain, as well as the overhead associated with each batch of transactions, and the L1 cost of settling transactions in the Arbitrum protocol.
  • Validator’s staking costs: In normal operation, one validator will need to be staked. The stake is assumed to be 0.2% of the total value of the chain (which is assumed to be $1 per user who is eligible to claim points). The cost of staking is the interest that could be earned on the money if it were not staked.
  • Validator computation and storage: Every validator must do computation to track the chain’s processing of transactions, and must maintain storage to keep track of the contracts’ EVM storage. The cost of computation and storage are estimated based on measurements, with the dollar cost of resources based on Amazon Web Services pricing.
It’s clear from our modeling that the predominant cost is for L1 calldata. This will probably be true for any plausible rollup-based system.
Our model also shows that Arbitrum can scale to workloads much larger than Reddit’s nominal workload, without exhausting L1 or L2 resources. The scaling bottleneck will ultimately be calldata on the L1 chain. We believe that cost could be reduced substantially if necessary by clever encoding of data. (In our design any compression / decompression of L2 transaction calldata would be done by client software and L2 programs, never by an L1 contract.)
9. Status of Arbitrum Rollup
Arbitrum Rollup is live on Ethereum testnet. All of the code written to date including everything included in the Reddit demo is open source and permissively licensed under the Apache V2 license. The first testnet version of Arbitrum Rollup was released on testnet in February. Our current internal version, which we used to benchmark the Reddit contracts, will be released soon and will be a major upgrade.
Both the Arbitrum design as well as the implementation are heavily audited by independent third parties. The Arbitrum academic paper was published at USENIX Security, a top-tier peer-reviewed academic venue. For the Arbitrum software, we have engaged Trail of Bits for a security audit, which is currently ongoing, and we are committed to have a clean report before launching on Ethereum mainnet.
10. Reddit Universe Arbitrum Rollup Chain
The benchmarks described in this document were all measured using the latest internal build of our software. When we release the new software upgrade publicly we will launch a Reddit Universe Arbitrum Rollup chain as a public demo, which will contain the Reddit contracts as well as a Uniswap instance and a Connext Hub, demonstrating how Community Points can be integrated into third party apps. We will also allow members of the public to dynamically launch ecosystem contracts. We at Offchain Labs will cover the validating costs for the Reddit Universe public demo.
If the folks at Reddit would like to evaluate our software prior to our public demo, please email us at [email protected] and we'd be more than happy to provide early access.
11. Even more scaling: Arbitrum Sidechains
Rollups are an excellent approach to scaling, and we are excited about Arbitrum Rollup which far surpasses Reddit's scaling needs. But looking forward to Reddit's eventual goal of supporting hundreds of millions of users, there will likely come a time when Reddit needs more scaling than any Rollup protocol can provide.
While Rollups greatly reduce costs, they don't break the linear barrier. That is, all transactions have an on-chain footprint (because all calldata must be posted on-chain), albeit a far smaller one than on native Ethereum, and the L1 limitations end up being the bottleneck for capacity and cost. Since Ethereum has limited capacity, this linear use of on-chain resources means that costs will eventually increase superlinearly with traffic.
The good news is that we at Offchain Labs have a solution in our roadmap that can satisfy this extreme-scaling setting as well: Arbitrum AnyTrust Sidechains. Arbitrum Sidechains are similar to Arbitrum Rollup, but deviate in that they name a permissioned set of validators. When a chain’s validators agree off-chain, they can greatly reduce the on-chain footprint of the protocol and require almost no data to be put on-chain. When validators can't reach unanimous agreement off-chain, the protocol reverts to Arbitrum Rollup. Technically, Arbitrum Sidechains can be viewed as a hybrid between state channels and Rollup, switching back and forth as necessary, and combining the performance and cost that state channels can achieve in the optimistic case, with the robustness of Rollup in other cases. The core technical challenge is how to switch seamlessly between modes and how to guarantee that security is maintained throughout.
Arbitrum Sidechains break through this linear barrier, while still maintaining a high level of security and decentralization. Arbitrum Sidechains provide the AnyTrust guarantee, which says that as long as any one validator is honest and available (even if you don't know which one will be), the L2 chain is guaranteed to execute correctly according to its code and guaranteed to make progress. Unlike in a state channel, offchain progress does not require unanimous consent, and liveness is preserved as long as there is a single honest validator.
Note that the trust model for Arbitrum Sidechains is much stronger than for typical BFT-style chains which introduce a consensus "voting" protocols among a small permissioned group of validators. BFT-based protocols require a supermajority (more than 2/3) of validators to agree. In Arbitrum Sidechains, by contrast, all you need is a single honest validator to achieve guaranteed correctness and progress. Notice that in Arbitrum adding validators strictly increases security since the AnyTrust guarantee provides correctness as long as any one validator is honest and available. By contrast, in BFT-style protocols, adding nodes can be dangerous as a coalition of dishonest nodes can break the protocol.
Like Arbitrum Rollup, the developer and user experiences for Arbitrum Sidechains will be identical to that of Ethereum. Reddit would be able to choose a large and diverse set of validators, and all that they would need to guarantee to break through the scaling barrier is that a single one of them will remain honest.
We hope to have Arbitrum Sidechains in production in early 2021, and thus when Reddit reaches the scale that surpasses the capacity of Rollups, Arbitrum Sidechains will be waiting and ready to help.
While the idea to switch between channels and Rollup to get the best of both worlds is conceptually simple, getting the details right and making sure that the switch does not introduce any attack vectors is highly non-trivial and has been the subject of years of our research (indeed, we were working on this design for years before the term Rollup was even coined).
12. How Arbitrum compares
We include a comparison to several other categories as well as specific projects when appropriate. and explain why we believe that Arbitrum is best suited for Reddit's purposes. We focus our attention on other Ethereum projects.
Payment only Rollups. Compared to Arbitrum Rollup, ZK-Rollups and other Rollups that only support token transfers have several disadvantages:
  • As outlined throughout the proposal, we believe that the entire draw of Ethereum is in its rich smart contracts support which is simply not achievable with today's zero-knowledge proof technology. Indeed, scaling with a ZK-Rollup will add friction to the deployment of smart contracts that interact with Community Points as users will have to withdraw their coins from the ZK-Rollup and transfer them to a smart contract system (like Arbitrum). The community will be best served if Reddit builds on a platform that has built-in, frictionless smart-contract support.
  • All other Rollup protocols of which we are aware employ a centralized operator. While it's true that users retain custody of their coins, the centralized operator can often profit from censoring, reordering, or delaying transactions. A common misconception is that since they're non-custodial protocols, a centralized sequencer does not pose a risk but this is incorrect as the sequencer can wreak havoc or shake down users for side payments without directly stealing funds.
  • Sidechain type protocols can eliminate some of these issues, but they are not trustless. Instead, they require trust in some quorum of a committee, often requiring two-third of the committee to be honest, compared to rollup protocols like Arbitrum that require only a single honest party. In addition, not all sidechain type protocols have committees that are diverse, or even non-centralized, in practice.
  • Plasma-style protocols have a centralized operator and do not support general smart contracts.
13. Concluding Remarks
While it's ultimately up to the judges’ palate, we believe that Arbitrum Rollup is the bakeoff choice that Reddit kneads. We far surpass Reddit's specified workload requirement at present, have much room to optimize Arbitrum Rollup in the near term, and have a clear path to get Reddit to hundreds of millions of users. Furthermore, we are the only project that gives developers and users the identical interface as the Ethereum blockchain and is fully interoperable and tooling-compatible, and we do this all without any new trust assumptions or centralized components.
But no matter how the cookie crumbles, we're glad to have participated in this bake-off and we thank you for your consideration.
About Offchain Labs
Offchain Labs, Inc. is a venture-funded New York company that spun out of Princeton University research, and is building the Arbitrum platform to usher in the next generation of scalable, interoperable, and compatible smart contracts. Offchain Labs is backed by Pantera Capital, Compound VC, Coinbase Ventures, and others.
Leadership Team
Ed Felten
Ed Felten is Co-founder and Chief Scientist at Offchain Labs. He is on leave from Princeton University, where he is the Robert E. Kahn Professor of Computer Science and Public Affairs. From 2015 to 2017 he served at the White House as Deputy United States Chief Technology Officer and senior advisor to the President. He is an ACM Fellow and member of the National Academy of Engineering. Outside of work, he is an avid runner, cook, and L.A. Dodgers fan.
Steven Goldfeder
Steven Goldfeder is Co-founder and Chief Executive Officer at Offchain Labs. He holds a PhD from Princeton University, where he worked at the intersection of cryptography and cryptocurrencies including threshold cryptography, zero-knowledge proof systems, and post-quantum signatures. He is a co-author of Bitcoin and Cryptocurrency Technologies, the leading textbook on cryptocurrencies, and he has previously worked at Google and Microsoft Research, where he co-invented the Picnic signature algorithm. When not working, you can find Steven spending time with his family, taking a nature walk, or twisting balloons.
Harry Kalodner
Harry Kalodner is Co-founder and Chief Technology Officer at Offchain Labs where he leads the engineering team. Before the company he attended Princeton as a Ph.D candidate where his research explored economics, anonymity, and incentive compatibility of cryptocurrencies, and he also has worked at Apple. When not up at 3:00am writing code, Harry occasionally sleeps.
submitted by hkalodner to ethereum [link] [comments]

Ethereum's Fork & Bitcoin's Block Size: Different Dramas ... EB82 – Mike Hearn - Blocksize Debate At The Breaking Point Bitcoin Q&A: Scaling and the block size debate - YouTube Cryptocurrency News - YouTube Riccardo Spagni talking the bitcoin blocksize @ On-chain scaling event

When Satoshi Nakamoto created Bitcoin in 2008, he didn’t introduce a block size limit. That didn’t happen until 2010, when he instituted a 1 MB limit. There was some mild debate around block sizes at that time, but the issue became increasingly pressing over the next five years as Bitcoin’s transaction volume began to climb. 10/10/2020 Trending Bitcoin News and Market Sentiment, Weekly Edition October 10th, 2020: Bitcoin Brushes Past $11,000 as Twitter CEO’s $50M Bitcoin Buy Follows Positive Comments on Blockchain; 02/10/2020 Trending Bitcoin News and Market Sentiment, Weekly Edition, 2nd October, 2020: US Regulators Win String of Victories, Bitcoin’s Longest Stay Above $10,000 If you're a miner, only mine at pools that support the block size limit and ask your pool to publicly say so. If you are a user, ignore anyone trying to change the bitcoin software you use to increase the one mega byte block size and tell people you transact with that you support keeping bitcoin decentralized and out of the hands of the existing corporate system. Remember, bitcoin is ... The fork of Bitcoin that wins mass adoption will be the one that recognizes that there is no ideal transaction fee and no ideal block size. There is only the market and economic actors in that ... Remove the block size limit completely. With the bitcoin industry poised to take off, the network is likely to find itself in this very similar situation much later on, even when the limit is increased to a certain level. There will be more and more transactions to process, weighing on the capacity of miners and reviving the need to make another cap adjustment. With that, some proposed that ...

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Ethereum's Fork & Bitcoin's Block Size: Different Dramas ...

New, updates, calculations, theories about Bitcoin and Alt Coins with open livestream discussions. Monero developer Riccardo Spagni (@fluffyponyza) at the on-chain scaling event talking about the Bitcoin blocksize limit and solutions (Flexible blocksize) - Recorded at 2016-06-24 with Snagit. In this talk in Berlin, Andreas looks at the inner structure of bitcoin and how high-level financial and trust applications are composed from smaller element... The highly-charged debates around both Ethereum's potential hardfork and Bitcoin's block size appear different on the surface, but are caused by the same des... Bitcoin rewards last fell on 9 July 2016 at the point of the second halving – an event which saw the Block reward fall from 25 new bitcoin per block to 12.5 bitcoin.

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