├── tests
    ├── simplechain.php
    └── hackchain.php
├── README.md
├── block.php
└── blockchain.php


/tests/simplechain.php:
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 1 | <?php
 2 | require_once(__DIR__.'/../blockchain.php');
 3 | 
 4 | /*
 5 | Set up a simple chain and mine two blocks.
 6 | */
 7 | 
 8 | $testCoin = new BlockChain();
 9 | 
10 | echo "mining block 1...\n";
11 | $testCoin->push(new Block(1, strtotime("now"), "amount: 4"));
12 | 
13 | echo "mining block 2...\n";
14 | $testCoin->push(new Block(2, strtotime("now"), "amount: 10"));
15 | 
16 | echo json_encode($testCoin, JSON_PRETTY_PRINT);
17 | 


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/README.md:
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 1 | # PHP BlockChain
 2 | 
 3 | PHP Blockchain is a simple implementation of the blockchain data structure and proof-of-work using the PHP programming language. It is designed as an introduction to blockchain technology for PHP programmers.
 4 | 
 5 | To run, download the source code, and, from the command line, run:
 6 | 
 7 | php tests/simplechain.php
 8 | 
 9 | This will output a simple blockchain with 3 blocks.
10 | 
11 | php tests/hackchain.php
12 | 
13 | This will validate the chain before and after a block is changed and shows the immutability of blockchains.


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/block.php:
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 1 | <?php
 2 | class Block
 3 | {
 4 |     public $nonce;
 5 | 
 6 |     public function __construct($index, $timestamp, $data, $previousHash = null)
 7 |     {
 8 |         $this->index = $index;
 9 |         $this->timestamp = $timestamp;
10 |         $this->data = $data;
11 |         $this->previousHash = $previousHash;
12 |         $this->hash = $this->calculateHash();
13 |         $this->nonce = 0;
14 |     }
15 | 
16 |     public function calculateHash()
17 |     {
18 |         return hash("sha256", $this->index.$this->previousHash.$this->timestamp.((string)$this->data).$this->nonce);
19 |     }
20 | }
21 | 


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/tests/hackchain.php:
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 1 | <?php
 2 | require_once(__DIR__.'/../blockchain.php');
 3 | 
 4 | /*
 5 | Hack the chain, changing values in the first block.
 6 | */
 7 | 
 8 | $testCoin = new BlockChain();
 9 | 
10 | echo "mining block 1...\n";
11 | $testCoin->push(new Block(1, strtotime("now"), "amount: 4"));
12 | 
13 | echo "mining block 2...\n";
14 | $testCoin->push(new Block(2, strtotime("now"), "amount: 10"));
15 | 
16 | echo "Chain valid: ".($testCoin->isValid() ? "true" : "false")."\n";
17 | 
18 | echo "Changing second block...\n";
19 | $testCoin->chain[1]->data = "amount: 1000";
20 | $testCoin->chain[1]->hash = $testCoin->chain[1]->calculateHash();
21 | 
22 | echo "Chain valid: ".($testCoin->isValid() ? "true" : "false")."\n";
23 | 


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/blockchain.php:
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 1 | <?php
 2 | require_once("./block.php");
 3 | 
 4 | /**
 5 |  * A simple blockchain class with proof-of-work (mining).
 6 |  */
 7 | class BlockChain
 8 | {
 9 |     /**
10 |      * Instantiates a new Blockchain.
11 |      */
12 |     public function __construct()
13 |     {
14 |         $this->chain = [$this->createGenesisBlock()];
15 |         $this->difficulty = 4;
16 |     }
17 | 
18 |     /**
19 |      * Creates the genesis block.
20 |      */
21 |     private function createGenesisBlock()
22 |     {
23 |         return new Block(0, strtotime("2017-01-01"), "Genesis Block");
24 |     }
25 | 
26 |     /**
27 |      * Gets the last block of the chain.
28 |      */
29 |     public function getLastBlock()
30 |     {
31 |         return $this->chain[count($this->chain)-1];
32 |     }
33 | 
34 |     /**
35 |      * Pushes a new block onto the chain.
36 |      */
37 |     public function push($block)
38 |     {
39 |         $block->previousHash = $this->getLastBlock()->hash;
40 |         $this->mine($block);
41 |         array_push($this->chain, $block);
42 |     }
43 | 
44 |     /**
45 |      * Mines a block.
46 |      */
47 |     public function mine($block)
48 |     {
49 |         while (substr($block->hash, 0, $this->difficulty) !== str_repeat("0", $this->difficulty)) {
50 |             $block->nonce++;
51 |             $block->hash = $block->calculateHash();
52 |         }
53 | 
54 |         echo "Block mined: ".$block->hash."\n";
55 |     }
56 | 
57 |     /**
58 |      * Validates the blockchain's integrity. True if the blockchain is valid, false otherwise.
59 |      */
60 |     public function isValid()
61 |     {
62 |         for ($i = 1; $i < count($this->chain); $i++) {
63 |             $currentBlock = $this->chain[$i];
64 |             $previousBlock = $this->chain[$i-1];
65 | 
66 |             if ($currentBlock->hash != $currentBlock->calculateHash()) {
67 |                 return false;
68 |             }
69 | 
70 |             if ($currentBlock->previousHash != $previousBlock->hash) {
71 |                 return false;
72 |             }
73 |         }
74 | 
75 |         return true;
76 |     }
77 | }
78 | 


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