├── blockchain-aymen .jpg
├── tsconfig.json
├── main.ts
├── package.json
├── BlockChain.ts
├── Block.ts
└── README.md


/blockchain-aymen .jpg:
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https://raw.githubusercontent.com/aymen94/simple-Blockchain/HEAD/blockchain-aymen .jpg


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/tsconfig.json:
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1 | {
2 |     "compilerOptions": {
3 |         "target": "es5",
4 |         "sourceMap": true
5 |     }
6 | }


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/main.ts:
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 1 | import { BlockChain } from './BlockChain';
 2 | import { Block } from './block';
 3 | 
 4 | 
 5 | var AyCoin = new BlockChain(3);
 6 | 
 7 | AyCoin.addBlock(new Block(1,{user:"Aymen Naghmouchi",Amount:100}));
 8 | AyCoin.addBlock(new Block(2,{user:"Aymen Naghmouchi",Amount:2500}));
 9 | AyCoin.addBlock(new Block(3,{user:"Aymen Naghmouchi",Amount:50}));
10 | 
11 | 
12 | 
13 | console.log(JSON.stringify(AyCoin,null,2));
14 | 
15 | console.log("all blocks are linked? "+AyCoin.checkBlockChain());
16 | 


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/package.json:
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 1 | {
 2 |   "name": "blockchain",
 3 |   "version": "1.0.0",
 4 |   "description": "blockchai tutorial",
 5 |   "main": "main.js",
 6 |   "dependencies": {
 7 |     "crypto-js": "^3.1.9-1"
 8 |   },
 9 |   "devDependencies": {},
10 |   "scripts": {
11 |     "test": "tsc main.ts",
12 |     "start": "node main.js"
13 |   },
14 |   "keywords": [
15 |     "blockchain",
16 |     "javascript",
17 |     "typescript",
18 |     "learn",
19 |     "structure"
20 |   ],
21 |   "author": "Aymen Naghmouchi",
22 |   "license": "ISC"
23 | }
24 | 


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/BlockChain.ts:
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 1 | import { Block } from './Block';
 2 | 
 3 | export class BlockChain{
 4 |  private chain:Array<Block>;
 5 |  private miningDifficulty:number;
 6 | 
 7 |  constructor(miningD:number){
 8 |    this.chain=new Array<Block>(new Block(0,{ firstBlock:"Created By Aymen Naghmouchi"}));
 9 |    this.miningDifficulty=miningD;
10 |  }
11 | 
12 |  public getLastBlock():Block{
13 |   return this.chain[this.chain.length-1];
14 |  }
15 | 
16 |  public addBlock(newBlock:Block){
17 |    newBlock.setPrecedentHash(this.getLastBlock().getHashBlock());
18 |    newBlock.mineBlock(this.miningDifficulty);
19 |    this.chain.push(newBlock);
20 |   }
21 | 
22 |  
23 | 
24 |   public checkBlockChain():boolean{
25 |     for(let i:number=1;i<this.chain.length;i++){
26 |       let actualblock:Block=this.chain[i];
27 |       let precedentblock:Block=this.chain[i-1];
28 |       if(actualblock.getPrecedentHash()!==precedentblock.getHashBlock())
29 |         return false;
30 |     }
31 |     return true;
32 |   }
33 | }
34 | 
35 | 


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/Block.ts:
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 1 | import  SHA256 =require('crypto-js/sha256');
 2 | 
 3 | export class Block{
 4 |  private index:number;
 5 |  private timestamp:Date;
 6 |  private data:any;
 7 |  private precedentHash:any;
 8 |  private hashBlock:any;
 9 |  private nonce:number;
10 | 
11 |  public constructor(index,data){
12 |   this.index=index;
13 |   this.timestamp=new Date();
14 |   this.data=data;
15 |   this.generateHash();
16 |   this.nonce=0;
17 |  }
18 | 
19 |  public getHashBlock(){
20 |   return this.hashBlock;
21 |  }
22 | 
23 |  public getPrecedentHash(){
24 |   return this.precedentHash;
25 |  }
26 |  public setPrecedentHash(hash:any){
27 |    this.precedentHash=hash;
28 |  }
29 |  public  generateHash(){
30 |  this.hashBlock=SHA256(this.index+this.precedentHash+this.timestamp+this.data+this.nonce).toString();
31 |   }
32 | 
33 |   public mineBlock(miningDifficulty:number){
34 |     while(this.hashBlock.substring(0,miningDifficulty)!=Array(miningDifficulty+1).join('0')){
35 |       this.nonce++;
36 |       this.generateHash();
37 |     }
38 |   }
39 | }
40 | 


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/README.md:
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  1 | # How to Work BlockChain  
  2 | how to work blockchain, this is only example structure. :smiley:
  3 | 
  4 | small tutorial with code to try to create your blockchain.
  5 | 
  6 | I used typescript because is very easy to read/understand.
  7 | 
  8 | -----------------------------------------------------------------------------------------------------
  9 | 
 10 | ## Block.ts
 11 | 
 12 | ### Instance variable
 13 | - index ===> index block.
 14 | 
 15 | - timestamp ===> date of block instance.
 16 | 
 17 | - data ===> any type of  data to save in block
 18 | 
 19 | - precedentHash ===>hash of the last block (lock added before this block).
 20 | 
 21 | - hashBlock ===> hash of this block.
 22 | 
 23 | - nonce ===>it has nothing to do with blocking, change to something random (example random number).
 24 | 
 25 | 
 26 | #### constructor block
 27 | ```
 28 | public constructor(index,data)
 29 | ```
 30 | 
 31 | #### methods of the block.
 32 | ```
 33 |  public getHashBlock();
 34 |  
 35 |  public getprecedentHash();
 36 | 
 37 |  public setPrecedentHash(hash);
 38 |  
 39 |  public  generateHash();
 40 |  
 41 | ```
 42 | 
 43 | > Proof-of-work  is used to  make secure the blockchain(similar bitcoin Hashcash)
 44 | 
 45 | > more info https://en.wikipedia.org/wiki/Proof-of-work_system
 46 | ```
 47 | public mineBlock(miningDifficulty:number){
 48 |     while(this.hashBlock.substring(0,miningDifficulty)!=Array(miningDifficulty+1).join('0')){
 49 |       this.nonce++;
 50 |       this.generateHash();
 51 |   }
 52 | ```
 53 | 
 54 | -----------------------------------------------------------------------------------------------------------
 55 | ## BlockChain.ts
 56 | ### Instance variable
 57 | - chain:Array<Block> ===>  array of block,(better chained list).
 58 | - miningDifficulty ===> the difficulty of mining expressed in numbers(the more the number is high the more the difficulty increases).
 59 |  
 60 |  #### constructor BlockChain
 61 |  > as a parameter it takes the difficulty of mining. 
 62 |  > when to start the blockchain, add the first block (this block is without the previous hash block because is the first block)
 63 |   ```
 64 |  constructor(miningD){
 65 |    this.chain=new Array<Block>(new Block(0,{ firstBlock:"Created By Aymen Naghmouchi"}));
 66 |    this.miningDifficulty=miningD;
 67 |  }
 68 |  ```
 69 |  
 70 |  #### methods of the BlockChain.
 71 | ```
 72 |   public getLastBlock();
 73 |   
 74 |   public checkBlockChain();
 75 |   
 76 | ```
 77 | 
 78 | > set the precedent block hash in the last added and regenerate her hash
 79 | ```
 80 |  public addBlock(newBlock){
 81 |    newBlock.setPrecedentHash(this.getLastBlock().getHashBlock());
 82 |    newBlock.mineBlock(this.miningDifficulty);
 83 |    this.chain.push(newBlock);
 84 |   }
 85 | ```
 86 | ![Alt text](https://raw.githubusercontent.com/aymen94/simple-Blockchain/master/blockchain-aymen%20.jpg?raw=true "Blockchain")
 87 | 
 88 | 
 89 | > check all blocks are linked among them.
 90 | ```
 91 | 
 92 |   public checkBlockChain():boolean{
 93 |     for(let i:number=1;i<this.chain.length;i++){
 94 |       let actualblock:Block=this.chain[i];
 95 |       let precedentblock:Block=this.chain[i-1];
 96 |       if(actualblock.getPrecedentHash()!==precedentblock.getHashBlock())
 97 |         return false;
 98 |     }
 99 |     return true;
100 |   }
101 | ```
102 | 
103 | # OUTPUT
104 | ```
105 | {
106 |   "chain": [
107 |     {
108 |       "index": 0,
109 |       "timestamp": "2018-01-21T14:23:12.424Z",
110 |       "data": {
111 |         "firstBlock": "Created By Aymen Naghmouchi"
112 |       },
113 |       "hashBlock": "47234aa1697b3fd20bc5db17b899ac0d1d6adc7608cbca7fbdcd515d89c81954",
114 |       "nonce": 0
115 |     },
116 |     {
117 |       "index": 1,
118 |       "timestamp": "2018-01-21T14:23:12.428Z",
119 |       "data": {
120 |         "user": "Aymen Naghmouchi",
121 |         "Amount": 100
122 |       },
123 |       "hashBlock": "0008d50dfd76575392335a0df6b82d52826c75ee827b0c639c77405dc40b22cc",
124 |       "nonce": 4636,
125 |       "precedentHash": "47234aa1697b3fd20bc5db17b899ac0d1d6adc7608cbca7fbdcd515d89c81954"
126 |     },
127 |     {
128 |       "index": 2,
129 |       "timestamp": "2018-01-21T14:23:12.515Z",
130 |       "data": {
131 |         "user": "Aymen Naghmouchi",
132 |         "Amount": 2500
133 |       },
134 |       "hashBlock": "0000c505fb52117656109daff8c9d18325b782b9674eb6f0d64840de43f0f0cc",
135 |       "nonce": 4302,
136 |       "precedentHash": "0008d50dfd76575392335a0df6b82d52826c75ee827b0c639c77405dc40b22cc"
137 |     },
138 |     {
139 |       "index": 3,
140 |       "timestamp": "2018-01-21T14:23:12.566Z",
141 |       "data": {
142 |         "user": "Aymen Naghmouchi",
143 |         "Amount": 50
144 |       },
145 |       "hashBlock": "000fd901ae1c2622cb9b48a801099d8f5c884d73b86402078cdf9eea78c787eb",
146 |       "nonce": 1479,
147 |       "precedentHash": "0000c505fb52117656109daff8c9d18325b782b9674eb6f0d64840de43f0f0cc"
148 |     }
149 |   ],
150 |   "miningDifficulty": 3
151 | }
152 | all blocks are linked? true
153 | ```
154 | 
155 | 
156 | 
157 | ## How to use
158 | * git clone or fork it
159 | * npm install
160 | * npm start
161 | 
162 | ### compile
163 | ```
164 | tsc main.ts
165 | ```
166 | ### execute
167 | ```
168 | node main.js
169 | ```
170 | 


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