使用多个密钥的 PHP 加密

Question

有没有办法以字符串格式生成两个相互依赖的键？

1. 主密钥（用于解密数据）
2. 从属密钥（依赖于主密钥，只能解密数据）

Answer 1

没有什么比代码故事更能解释这个概念了；p

这是一个示例，其中 alice 仅使用 bobs 公钥向 bob 发送加密消息，然后 bob 使用仅使用 alices 公钥的加密消息进行响应。

在这两种情况下，他们自己的私钥都用于解密消息。

<?php

// define an example, our people, messages and their keys
$people = [
    'alice' => [
        'keys' => gen_keys(),
        'msg' => 'Hi Bob, I\'m sending you a private message'
    ],    
    'bob' => [
        'keys' => gen_keys(),
        'msg' => 'Thanks Alice, message received'
    ]  
];

//
$encrypted = $decrypted = [
    'alice' => '',
    'bob'   => ''
];

// public keys get exchanged, not private

// alice encrypts her message to bob
$encrypted['bob'] = encrypt(
    $people['alice']['msg'],         // message to encrypt
    $people['bob']['keys']['public'] // bobs public key, which he sent to alice
);

// message sent to bob

// bob decrypts his message
$decrypted['bob'] = decrypt(
    $encrypted['bob'],                // message to decrypt
    $people['bob']['keys']['private'] // bob's private key, which he uses to decrypt the message
);

// bob now responds

// bob encrypts his message to alice
$encrypted['alice'] = encrypt(
    $people['bob']['msg'],             // message to encrypt
    $people['alice']['keys']['public'] // alice public key, which she sent to bob
);

// alice decrypts her message
$decrypted['alice'] = decrypt(
    $encrypted['alice'],                // message to decrypt
    $people['alice']['keys']['private'] // alice's private key, which she uses to decrypt the message
);

//
print_r($decrypted);

/*
Array
(
    [alice] => Thanks Alice, message received
    [bob] => Hi Bob, I'm sending you a private message
)
*/

/**
 * Functions - wraps for openssl operations
 */
// generate public and private key pair
function gen_keys() {
    $res = openssl_pkey_new(array('private_key_bits' => 2048));

    /* Extract the private key */
    openssl_pkey_export($res, $privateKey);

    /* Extract the public key */
    $publicKey = openssl_pkey_get_details($res);

    return ['public' => $publicKey["key"], 'private' => $privateKey];
}

// encrypt using public key
function encrypt($msg, $key) {
    $ret = '';
    openssl_public_encrypt(
        $msg, // message to encrypt
        $ret, // &encrypted message
        $key  // public key
    );
    return $ret;
}

// decrypts using private key
function decrypt($msg, $key) {
    $ret = '';
    openssl_private_decrypt(
        $msg, // message to decrypt
        $ret, // &decrypted message
        $key  // private key
    );
    return $ret;
}

Answer 2

是的，它被称为非对称加密。使用公钥对数据进行加密，然后使用私钥对数据进行解密。这用于许多地方，例如在区块链、支付门户等领域。

你可以在这里找到一些有用的算法和理论来帮助理解：https://www.tutorialspoint.com/cryptography/public_key_encryption.htm

在 PHP 中，您可以使用 - openssl_encrypt() 和 openssl_decrypt() - 来获得类似的结果，或者 - base64_encode() 和 base64_decode() 或者您可以将两者混合使用以获得更安全的解决方案。

一个简单的例子可以是：

function my_simple_crypt( $string, $action = 'e' ) {
    // you may change these values to your own
    $secret_key = 'my_simple_secret_key';
    $secret_iv = 'my_simple_secret_iv';

    $output = false;
    $encrypt_method = "AES-256-CBC";
    $key = hash( 'sha256', $secret_key );
    $iv = substr( hash( 'sha256', $secret_iv ), 0, 16 );

    if( $action == 'e' ) {
        $output = base64_encode( openssl_encrypt( $string, $encrypt_method, $key, 0, $iv ) );
    }
    else if( $action == 'd' ){
        $output = openssl_decrypt( base64_decode( $string ), $encrypt_method, $key, 0, $iv );
    }

    return $output;
}

加密：

$encrypted = my_simple_crypt( 'Hello World!', 'e' );

解密：

$decrypted = my_simple_crypt( 'Hello World!', 'd' );

来源：https://nazmulahsan.me/simple-two-way-function-encrypt-decrypt-string/