BitCoin Tutorial

初学者入门

http://www.coindesk.com/information/

bitcoin是什么？

1：与传统货币的重要区别：bitcoin is decentrallized.

2:bitcoin is not unlimited, only 21 million bitcoins can ever be created by miners.

3:a bitcoin can be divided into smalller parts,1 BitCoin = 1 Mil Satoshi.

4:bitcoin is based on mathematics,and the mathematical formula is open source. 

5:bitcoin adreess is not linked to personal info.

6:bitcoin stores ledger in the block chain,it's transparent ,anyone call tell the bitcoin numbers through a bitcoin address.

7:transaction fees are miniscule.

8:transaction is non-repudiable.

谁是中本聪？

1:the inventor of bitcoin protocol.

2:Satoshi is still not confirmed.

为什么要用bitcoin？

1:transactions are fast.

2:transaction fees are cheap

3:no central authority has control.

4:there're no chargebacks.

5:more safe,bitcoin address is the public key,before send a bitcoin you has to create a certificate combined by the public and private key.

6:it isn't inflationary(通货膨胀) cause  the number of the bitcoins is limited.

     convential currency will cause the dollar's value decrease if the Federal Reserve(美联储) prints  more money. 

7:it's private. 

     a bitcoin address is like a transparent wallet without visiable owners.but using the same address consistently will increase the risk.

8:you need not to trust anyone(like banks,merchants),it's open source system.

9:you own it. private key is in your own hands,no one can freeze your money.

10:create your own money if you have enough computing power.

如何购买bitcoin？

1:from? regular exchanges,other people.  impossible to buy bitcoins by credit card(avoid chargeback)

2:get a bitcoin wallet.

     2 kinds:A-wallet stored on hard drive B-online web based service

     缺陷:local-u have to backup regualarly in case of corruption;online-varity degrees of security against hackers.

     popular online wallet:CoinBase,Blockchain.info.

     exchange options depends on your location(Law) fiat currency:法币

      link a bank account to the exchange account(delays and fees)

     

3:warning:no insurance of your account(exchanges out of business or hackers)

4:face-to-face or over-the-counter trades.

about Mining

as time goes increasing the difficulity and energy of mining,individual is not cost effective. most is guilds or compay managed mine.

pay for cloud mining.

Bitcoin Investment Trust:currently exclusively for the rich.

Bitcoin ATMs: very few exists,but easy to use and more popular.

总结:bitcoin 购买目前门槛还是较高.number of options is increasing.

how-to-store-your-bitcoins

bitcoin wallet 的几种类型:

     Desktop wallets:original bitcoin client-BitCoin-Qt;Multibit;Hive;secure wallet:Armory;anonymous:DarkWallet;

     Mobile wallets:feature:convenient,not full bitcoin clients(bitcoin block chain too large:GB); Mycelium; Blockchain; Kipochi;Apple off-shelf Blockchain.info.

     Online wallets: Coinbase; Blockchain; Strongcoin;not safe;

     Hardware wallets:limited in number;

are wallets 安全? on condition

are wallets 隐蔽? bitcoin is transparent and trackable,ideas:   Merge Avoidance ,  Stealth Addresses , and Coin Mixing .currently: Dark Wallet

如何让wallet更安全？

     encrypt it;

     back up wallet;

     take it offline：cold storage wallets;paper bitcoin 

paper-wallet-tutorial

为什么要选paper wallet？  protect u from hard-drive-crash or hackers.

paper-wallet是什么?copies of public and private keys.一般都印有QR-code(二维码)

创建paper-wallet步骤：

 在 BitAddress.org或 LiteAddress.org生成private and public key的QR-code后打印并保存。 

what-can-you-buy-with-bitcoins

用比特币购买实物:接受bitcoin支付的 online merchants，但有商品种类限制、区域限制。 Overstock， Shopify  

比特币gift-card:

接受比特币的消费场所：

bitcoin赌博网站：

黄金交易：

bitcoin拍卖场：

online-service:

is-bitcoin-legal

how-bitcoin-mining-works

block=transactions data of specified period.

miner's job? confirm transactions and write ledgers.

block chain = general ledger = a list of blocks

miners 提取block中的信息，通过一个数学算法，生成一个hash，这个hash和block一同放在chain的末尾。

hash的属性：1:生成的hash看不出它对应的原数据.2:hash是唯一的，对block中数据的任一改动，它对应的hash都会变化.

生成hash所使用的元数据包括1：block中的transaction data 2：上一个block的hash。

这就像蜡封一样，这就保证了任一block和其后的的block都是合法的。

如果你想通过修改某个block中的数据来伪造transaction,那这样做肯定会改变block的hash。如果有人核实block，很容易发现被修改后的block的hash和原hash不同，

篡改某个block会导致其后连续的block的hash错误，因此会抛弃所有不正常block。

miners seal off blocks,成功生成一个hash会得到25bitcoins 的reward,这就是mining的动机.

为了增加hash的难度，bitcoin协议引入了proof of work的的东西。bitcoin协议的hash和以往概念的hash略有不同，它要求hash值的开头前要有一定数量的0。

as soon as you include new data into the mix,the hash will be totally changed.

nonce = a random piece of data.使用nonce和transaction data生成hash的要符合指定的format,所以找到合适的nonce非常困难，这就是miner在做的工作。

视频教程：

需要了解的概念：

bitcoin{decentralized(P2P),Crypto.currency}

Double spending

POW(proof of work)

Cryptographic hash function

SHA-256(proceed SHA-1) MD5  for digital signature

message ->hash function->digest(fixed length)

computationally efficient.

Collision Resistant

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