回目录 《区块链：深度解析》
# 1. 区块链深度基础
# 1.1 Mining AND Consensus Algorithm 挖矿与共识
详解在另一篇 《区块链基础：解密挖矿与共识的误解》
Consensus is a form of automated governance that populates and publishes ledger entries every x period. The “blockchain” is proof that this automated governance structure actually works as designed, providing near ABSOLUTE assurance over the integrity of the ledger data.
- https://blog.goodaudience.com/1-assurances-in-crypto-14c55a1fd616
POW POS DAG are not consensus protocol, they are “mining mechanism” or “sybil control mechanisms” specifically https://twitter.com/el33th4xor/status/1006931658338177024 Consensus Protocol is the process of accepting transactions(validate transactions on receive) and blocks(validate pow/pos[block headers] and actual payloads[block transactions] on receive) PoW, PoS and DAGs are NOT consensus protocols https://medium.com/coinmonks/a-primer-on-blockchain-design-89605b287a5a
# 1.1.1 Mining mechanism
Lottery game, find solve for puzzle Proof of Work vs. Proof of Stake – What’s the Difference, and Which is Better? www.livebitcoinnews.com/proof-work-vs-proof-stake-whats-difference-better/ https://ethereum.stackexchange.com/questions/15176/logic-of-ethereum-consensus-part-1 https://ethereum.stackexchange.com/questions/15177/logic-of-ethereum-consensus-part-2 https://medium.com/@robertgreenfieldiv/explaining-proof-of-stake-f1eae6feb26f https://blockgeeks.com/guides/proof-of-work-vs-proof-of-stake/ Understanding Blockchain Fundamentals, Part 2: Proof of Work & Proof of Stake https://medium.com/loom-network/understanding-blockchain-fundamentals-part-2-proof-of-work-proof-of-stake-b6ae907c7edb https://medium.com/@simoncheong/how-it-works-high-speed-super-large-ledger-technology-83b4d9a7e114
# 1.1.1.1 POW
Find nonce for block (block level) https://en.wikipedia.org/wiki/Proof-of-work_system
# 1.1.1.2 POS
Find utxo for coinstake transaction (transaction level) Coinstake transactions Staking transactions
Eth casper https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ
POS V1 Peercoin https://peercoin.net/whitepapers/peercoin-paper.pdf https://github.com/peercoin/rfcs
The proof-of-stake in the new type of blocks is a special transaction called coinstake (named after Bitcoin’s special transaction coinbase). In the coinstake transaction block owner pays himself thereby consuming his coin age, while gaining the privilege of generating a block for the network and minting for proof-of-stake. The first input of coinstake is called kernel and is required to meet certain hash target protocol, thus making the generation of proof-of-stake blocks a stochastic process similar to proof-ofwork blocks. However an important difference is that the hashing operation is done over a limited search space (more specifically one hash per unspent wallet-output per second) instead of an unlimited search space as in proof-of-work, thus no significant consumption of energy is involved. POS V3 The missing explanation of Proof of Stake Version 3 http://earlz.net/view/2017/07/27/1904/the-missing-explanation-of-proof-of-stake-version Qtum https://blog.qtum.org/qtums-proof-of-stake-consensus-at-a-high-level-ea53e051ac66
Implementation:
Stake(stay online, hold UTXOs of himself) => try every time interval, with ‘next block timestamp’, find “coinbase kernel”/”staking transaction”/coinstake transaction, that meets the target difficulty (calculated by utxo value) // Hash256("Stake Modifier V2" + "UTXO Transaction Timestamp" + "UTXO Transaction Hash" + "UTXO Output Number" + "Coinstake Transaction Time") < Target * Weight https://bitcoin.stackexchange.com/questions/52321/how-is-a-proof-of-stake-block-mined-at-the-block-level-and-how-does-it-accompli Proof-of-Stake (PoS) implementation https://academy.stratisplatform.com/FullNode/PoS/PoS-introduction.html
https://academy.stratisplatform.com/FullNode/ProvenHeaders/proven-headers-introduction.html
# 1.1.1.3 DPOS
DPOS共识算法—缺失的白皮书 https://lilymoana.github.io/DPOS.html
缺失的白皮书：DPOS共识算法工作原理及鲁棒性根源分析 https://www.leiphone.com/news/201706/JfsBmaf6Y0ZtV11R.html
DPOS Consensus Algorithm - The Missing White Paper https://steemit.com/dpos/@dantheman/dpos-consensus-algorithm-this-missing-white-paper
# 1.1.2 共识算法 Consensus Protocol
拜占庭将军问题具体参考《从故障容错分布式系统到拜占庭容错分布式账本》
Nakamoto consensus
https://github.com/bitcoinbook/bitcoinbook/blob/develop/ch10.asciidoc#decentralized-consensus Check pow (target difficulty) Check timestamp(between last 11 median and future 2 hours) Check transactions
https://www.youtube.com/watch?v=fw3WkySh_Ho Consensus Algorithms, Blockchain Technology and Bitcoin UCL - by Andreas M. Antonopoulos
PBFT
PBFT PracticalByzantineFaultTolerance http://pmg.csail.mit.edu/papers/osdi99.pdf 区块链共识算法 PBFT（拜占庭容错）、PAXOS、RAFT简述 https://blog.csdn.net/jerry81333/article/details/74303194 从Paxos到区块链 http://catkang.github.io/2018/03/24/paxos-pbft-pow.html [区块链] 共识算法之争（PBFT，Raft，PoW，PoS，DPoS，Ripple） https://www.cnblogs.com/X-knight/p/9157814.html
DPOS+PBFT https://bbs.asch.io/topic/1883/阿希的dpos-pbft共识机制是如何运作的
# 1.2 Permission design
whether permission is needed to access the blockchain;
# 1.3 cryptocurrency & smart contract
都是在矿工节点上验证执行，储存位置
# 1.4 安全问题-共识算法和智能合约
# 1.4.1 Consensus attack 共识漏洞
重放攻击 replay attack Dos denial-of-service Double spend Sybil attacks: Protected by mining mechanism (pow/pos)
opportunistic attacks Nothing-At-Stake problem https://www.youtube.com/watch?v=-XXV2q6206Q https://ethereum.stackexchange.com/questions/2402/what-exactly-is-the-nothing-at-stake-problem https://medium.com/coinmonks/understanding-proof-of-stake-the-nothing-at-stake-theory-1f0d71bc027 Long range attack https://www.youtube.com/watch?v=cct-YpOqOpA
Resource exhaustion attack(on pos) https://medium.com/@dsl_uiuc/fake-stake-attacks-on-chain-based-proof-of-stake-cryptocurrencies-b8b05723f806 http://fc19.ifca.ai/preproceedings/180-preproceedings.pdf https://github.com/initc3/i-cant-believe-its-not-stake
Time warp attack The Bitcoin Protocol (consensus rules) has two relevant rules for the timestamps in block headers: 1. A node will not accept a block whose timestamp is more than two hours in the future. 2. A node will not accept a block unless it has a timestamp greater than the median of the previous 11 blocks. In Bitcoin, we call this Median-Time-Past (MTP).
Blocks are considered valid if their time is greater than the median of the last 11 blocks and less than currentTime + 2 hours, so it's legal for an attacker to create a new version of an old block with a time far in the future. If this is the first block in a retarget period, then the difficulty will quadruple after that period. If it's the last block, then the difficulty will be divided by four. (Difficulty adjustments are limited to *4 or /4.) https://bitcoin.stackexchange.com/questions/75831/what-is-time-warp-attack-and-how-does-it-work-in-general https://blog.theabacus.io/the-verge-hack-explained-7942f63a3017 https://bitcoin.stackexchange.com/questions/1511/gaming-the-off-by-one-bug-difficulty-re-target-based-on-2015-instead-of-2016 https://bitcoin.stackexchange.com/questions/20597/where-exactly-is-the-off-by-one-difficulty-bug https://bitcointalk.org/index.php?topic=43692.msg521772#msg521772 https://bitcointalk.org/index.php?topic=43692.msg521772#msg521772 https://bitcointalk.org/index.php?topic=3256693.0
What prevents similar time-warp attacks in Bitcoin as happened to Verge? https://bitcoin.stackexchange.com/questions/75438/what-prevents-similar-time-warp-attacks-in-bitcoin-as-happened-to-verge https://forum.zcashcommunity.com/t/how-does-someone-find-a-17-blocks-in-4-seconds-time-warp-attack/1583/17
# 1.4.2 Contract attack 合约漏洞
DAO攻击 SmartMesh Announcement on Ethereum Smart Contract Overflow Vulnerability https://medium.com/@smartmesh/smartmesh-announcement-on-ethereum-smart-contract-overflow-vulnerability-f1ded8777720
干货分享：Qtum量子链开发者公开经典PoS协议的一个DoS攻击向量 www.8btc.com/qtum-pos-dos
# 1.4.3 交易漏洞
比如使用第三方的库要小心，可能会有坑
# 1.4.3 案例分析 attack analysis
https://en.bitcoin.it/wiki/Weaknesses https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures
** CVE-2018-17144: DOS & Double spend**
BitcoinCore CVE-2018-17144 漏洞研究与分析 https://paper.seebug.org/742/ https://hackernoon.com/bitcoin-core-bug-cve-2018-17144-an-analysis-f80d9d373362 https://bitcoin.stackexchange.com/questions/84026/reproduce-cve-2018-17144-inflation-bug-on-regtest-for-learning/86101#86101 Validation.cpp UpdateCoins CCoinsViewCache::SpendCoin() CCoinsViewCache::FetchCoin() CCoinsViewCache::AddCoin() Coin Flag 0 from parent(前驱区块） Dirty | FRESH （普通交易）
DIRTY 1<<0 = 1 （普通交易）
FRESH 1<<1 = 2
header first - fill-disk attack
https://bitcoin.stackexchange.com/questions/76018/how-does-headers-first-prevent-fill-disk-attack checkpoints https://en.bitcoin.it/wiki/Bitcoin_Core_0.11_(ch_5):_Initial_Block_Download#Checkpoints
Compact block https://bitcoincore.org/en/2016/06/07/compact-blocks-faq/
**deep reorg - network disruption **
On the new deep reorg protection https://www.reddit.com/r/btc/comments/9z1gjo/on_the_new_deep_reorg_protection/
Other
Pywallet安全事件https://www.chaindd.com/3125336.html
# 2. 張韡武学长讲座总结 Overview From zhang weiwu’s view
normal search - > binary search -> hastable -> collision (chain, prob)
Hash=>Digital Signature=>Blockchain
# 2.1 Hash
Non encrypted hasdh
Encrypted hash
Hmac Length extension attack
Encrypted hash -- along with other information, such as the hashing algorithm
Digital signature
# 2.2 Digital signature
Integrity Information not tampered Although encryption hides the contents of a message, it may be possible to change an encrypted message without understanding it. (Some encryption algorithms, known as nonmalleable ones, prevent this, but others do not.) However, if a message is digitally signed, any change in the message after signature invalidates the signature Authenticity Message is sent by the user Non-repudiation an entity that has signed some information cannot at a later time deny having signed it. Similarly, access to the public key only does not enable a fraudulent party to fake a valid signature
PKI based digital signature schema：
Dsa Rsa ecc
Blockchain based digital signature schema：
why? Example: I love you to someone face in face, that’s not unique, can be ‘double spend’ by saying I love you to someone else. I love you to someone broadcast to blockchain
Blockchain-Powered Digital Signatures https://sphereon.com/why-blockchain-powered-digital-signatures-are-better/ block chain, e-signature, and PKI/EIDAS https://www.quora.com/What-is-the-difference-between-block-chain-e-signature-and-PKI-EIDAS Blockchain and Digital Signatures https://medium.com/@lyaffe/blockchain-and-digital-signatures-376954738b4a Digital signatures and the blockchain https://www.linkedin.com/pulse/digital-signatures-blockchain-sean-au/ Using blockchains as an alternative to PKIs for digital signatures http://blog.pdf-tools.com/2016/10/using-blockchains-as-alternative-to.html
Transaction hash and Ecrecover Blockchain Transaction Authentication and Security www.ascdi.com/blockchain-transaction-authentication-and-security/
# 2.3 Merkle
1.someone hold private key sign the merke tree, like traditional ca sign it, or the gov will sign it 2.no central authority sign it, but it will be ‘signed’ by POW, by adding a nonuce or anymore values, to create a new hash preceding with enough 0s
the block in blockchain explained (merkle trees) http://haroldcarr.com/posts/2017-07-31-the-block-in-blockchain-merkle-trees.html
ETH Patricia Tries: Merkle Trees and Patricia Tries - Blockchain for Developers [Lab 7] https://www.youtube.com/watch?v=wwrf87bq6jo EOS Merkle tree - LCV: https://github.com/EOSIO/Documentation/blob/master/TechnicalWhitePaper.md 通过EOS.IO的默克尔证明实现区块链间通信 https://www.weibo.com/ttarticle/p/show?id=2309404181938423384064 > EOS 的 Block 上只存了 Merkle root，并没有存整个 tree。这个问题 Vitalik Buterin 和 Dan 辩论过一次，V 认为 EOS 这是投机取巧，Dan 认为 Merkle tree 的存在是为了校验状态（交易是否存在），而状态应该是区块链上的记录回放的结果，不应该属于共识的一部分，也不用记录在区块上，并且 EOS 也是支持利用 Merkle 做轻客户端证明的。但具体 EOS 怎么存这个，我自己还没看太明白。 > https://zhuanlan.zhihu.com/p/34046714
Merkle in time
Bitmap , bloom filter
聊聊数字签名(Digital Signature) https://alphawallet.com/%E8%81%8A%E8%81%8A%E6%95%B0%E5%AD%97%E7%AD%BE%E5%90%8Ddigital-signature/
Blockchain will simplify business processes and ensure transparency and immutability while eliminating intermediaries in logistics and supply chains. Courses https://github.com/tari-labs
A step by step guide to operate and tokenise your car ownership using Ethereum and IoT https://link.medium.com/iCTVkYyW94 How to empower small business with Tokenisation, the true killer app for ethereum by https://link.medium.com/zestYsbR84 Elizabeth Warren wants to break down Amazon — then what? https://link.medium.com/FQvCCv06h5 What is a token? Token-economy 101 https://link.medium.com/HMF3gyd6h5 What is Trust? A preparation for thinking in blockchain. https://link.medium.com/cZIMc9ZZh5 The way we treat data on the blockchain is wrong — this is how it’s supposed to work https://link.medium.com/zOb2EJZ6h5 I failed to purchase $70,000 crypto from CoinTree — that’s good news for you! https://link.medium.com/dIHcbqe6h5 People fear cryptocurrency… and that’s good news for YOU! https://link.medium.com/Q5UcyDb6h5 Defying the banks with DeFi & AlphaWallet by https://link.medium.com/dc1t4906h5
How does consensus protect from lying about transactions? https://bitcoin.stackexchange.com/questions/64605/how-does-consensus-protect-from-lying-about-transactions NO： Nakamoto consensus Miners have two separate functions in the consensus computer: checking that blocks are correctly constructed, or proof-of-work, and checking the validity of transactions in each block. While verifying correct block construction requires a relatively small amount of work (two SHA256 calculations), checking the validity of transactions contained in a block can take much more time for two reasons. First, the number of transactions per block may be large (≈ 800 in Bitcoin at the time of writing, and its capacity may soon be extended to support high transaction rates [6, 7]). Second, expressive transaction scripts in emerging cryptocurrencies such as Ethereum can require significant computational work to verify. These expressions create a new dilemma for miners — whether the miners should verify the validity of scripted transactions or accept them without verification. Miners are incentivized to verify all scripted transactions for the “common good” of the cryptocurrency so to speak. However, verifying scripts consumes computation resources and therefore delays honest miners in the race to mine the next block. We argue that this dilemma leaves open the possibility of attacks which result in unverified transactions on the blockchain. This means that some computation tasks outsourced to cryptocurrenncy-based consensus computers may not execute correctly.
Surviving Crypto Winter — Part One: Mattereum and the Internet of Agreements https://hackernoon.com/surviving-crypto-winter-part-one-mattereum-and-the-internet-of-agreements-19c99453060
作为一名区块链架构师，需要从哪几个纬度去做技术选型？ http://www.infoq.com/cn/articles/technology-selection-as-blockchain-architector
stratum协议原理 https://www.8btc.com/article/54210
全球交易所区块链最新发展及相关思考 https://mp.weixin.qq.com/s/MEN19UIawjjOb6OxqLyL9w
Alternatives to Blockchain https://medium.com/@jimmysong/alternatives-to-blockchain-9f858c0a1f2d https://weibo.com/ttarticle/p/show?id=2309404248299317160730
Drupal meet Blockchain, Blockchain meet Drupal. https://medium.com/@chainfrog/drupal-meet-blockchain-blockchain-meet-drupal-fe2e4b7b9f47