Alt Coins for Bitcoin

Block verification time Does block verification time (by all nodes in the network) takes up a large portion of the total block propagation time? What is the percentage, on average? http://bit.ly/2RoNOru

Coding challenge: finding nonce to mine this block On a coding challenge for a job at Celo: Find the nonce that mines this block, then enter it above to submit your resume. You can use the following available functions: sha1(str: string): string JSON.stringify(object: Object): string checkHash(hash: string, difficulty: number): bool const block = { blockNumber: 104413, parentHash: '0x4b1d39aedc8a83b5d87a84a915f66b9cb14e9e36', difficulty: 65536, resumeHash: 'fba689efd74ce23aa105384e720db42b59f1fecb', position: 'Software Engineer', name: 'John Smith', minedBy: 'john@microsoft.com', nonce: 0, } and i thought the following would work, target = 0x00ffff0000000000000000000000000000000000000000000000000000 / 65536 hash = sha1(JSON.stringify(block)) while (hash>target){ hash = sha1(JSON.stringify(block)) block.nonce++ } console.log(block.nonce-1) But how would the target work in this case? the target that i get would be 64 digit hex while sha1 ...

If the program is open source, how can I view "Transaction Create a new transaction" and "Sign Transaction"? Not long ago I saw on the site github.com the very first Nakamoto code: https://github.com/livegnik/BitCoin-v0.01-ALPHA Running bitcoin.exe, I did not find the console. If the program is open source, how can I view "Transaction Create a new transaction" and "Sign Transaction"? I know that the program is written in C++ I would love to see the "Transaction" processes as on https://coinb.in Coinbin source code is written in javascript. Can I view in C++? http://bit.ly/2FTuj97

What's the segwit transaction serialization "flag" field for? According to bip 141 , the segwit transaction serialization format (used to compute the wtxid) is: [nVersion][marker][flag][txins][txouts][witness][nLockTime] The bip mentions that the flag field MUST currently be 0x01. What's the purpose of this field? Is it some kind of upgrading mechanism of the serialization format? http://bit.ly/2S9BAal

Where is it safest to buy bitcoins in US What is the safest place to buy bitcoins in the US? I am looking for the sites that accept debt cards. Are all sites compatible with the Copay wallet? http://bit.ly/2S3fzKz

Do you really need more than 50% mining power in order to attack Bitcoin blockchain? My question is about concept, so code is not related, however, do you really need 51% of the mining power in order to attack/replace the real bitcoin Blockchain? For example, a blockchain has a length of 8, A, B, C, D, E each represent a individual with 20% of the total mining power, let's say person A and B decide to work together, but that's only 40% of the total mining power (less than 51%), for illustration purpose, miner C, D, E will always mine alone, so by the time miner C, D, E each finished mining the 9th block, A and B have already mined the 11th block (assuming they mine faster, since they work together and have a total mining power of 40%), so longest chain wins right? and now the 9th block that miner C, D, E just mined becomes invalid and their chain will be replaced to the longer blockchain, does this mean A and B might have the power to control and manipulate the entire bitcoin ...

Italy: Blockchain Opportunities, Market, Limitations & Broadcast – IDC Research Research conducted by IDC last year shows that 75.5% of companies worldwide believe blockchain technology will facilitate their Digital Transformation initiatives for the next half a decade. In Europe, however, uptake is still very low, the percentage of firms which are conducting pilot projects in blockchain makes around 9% of the total number interviewed, according to a report by Tech Economy. http://bit.ly/2DC61y3