Design of PHP asymmetric encryption algorithm (RSA) encryption mechanism

explain

Asymmetric encryption algorithm You need two keys ： Public key （publickey） And a private key （privatekey）.

• Public key and private key are a pair , If you encrypt data with a public key , Only the corresponding private key can be used to decrypt ;
• If you encrypt data with a private key , Then only the corresponding public key can be decrypted .
• Because encryption and decryption use two different keys , So this algorithm is called asymmetric encryption algorithm .

Use scenarios

PHP For the client To write API, Add... To the data / Decrypt .

Create private key 、 Public key

// Generate original  RSA Private key file 

openssl genrsa -out rsa_private_key.pem 1024

// The original  RSA Private key to  pkcs8 Format 

openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out private_key.pem

// Generate RSA Public key 

openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

// We will rsa_private_key.pem Used on the server side , Public key issued to android Follow ios Equal front end .

The private key here can use the original or pkcs8 Format , We send the public key to each other for decryption .

Server class library

<?php
/**
 * Created by PhpStorm.
 * Desc: Rsa class 
 * Coder: Wanzhou Chen
 * Date: 2022-06-24
 * Time: 14:46
 */

class Rsa
{

    private static $PRIVATE_KEY = '-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----';

    private static $PUBLIC_KEY = '-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDD6hyZeZ96wkr9CV7Qk3Xjaw/1
xvuxqCT7BmL4ytZ+ysSTI153LJa1qVbSql+H6sW0uxK73fdwGebBtcc8fAjWaFI5
eD2/KCS0YKBAODSLM6bbnLF3JMxndM5AtryE2Cdb2UwobkZMorNiow2hk37xT5Ie
4vMkzd9DORq2abS99QIDAQAB
-----END PUBLIC KEY-----';


    /**
     *  Get private key 
     * @return bool|resource
     */

    private static function getPrivateKey()

    {

        $privKey = self::$PRIVATE_KEY;

        return openssl_pkey_get_private($privKey);

    }


    /**
     *  To obtain the public key 
     * @return bool|resource
     */

    private static function getPublicKey()

    {

        $publicKey = self::$PUBLIC_KEY;

        return openssl_pkey_get_public($publicKey);

    }


    /**
     *  Private key encryption 
     * @param string $data
     * @return null|string
     */

    public static function privateEncrypt($data = '')

    {

        if (!is_string($data)) {

            return null;

        }

        return openssl_private_encrypt($data, $encrypted, self::getPrivateKey()) ? base64_encode($encrypted) : null;

    }


    /**
     *  Public key encryption 
     * @param string $data
     * @return null|string
     */

    public static function publicEncrypt($data = '')

    {

        if (!is_string($data)) {

            return null;

        }

        return openssl_public_encrypt($data, $encrypted, self::getPublicKey()) ? base64_encode($encrypted) : null;

    }


    /**
     *  Private key decryption 
     * @param string $encrypted
     * @return null
     */

    public static function privateDecrypt($encrypted = '')

    {

        if (!is_string($encrypted)) {

            return null;

        }

        return (openssl_private_decrypt(base64_decode($encrypted), $decrypted, self::getPrivateKey())) ? $decrypted : null;

    }


    /**
     *  Public key decryption 
     * @param string $encrypted
     * @return null
     */

    public static function publicDecrypt($encrypted = '')

    {

        if (!is_string($encrypted)) {

            return null;

        }

        return (openssl_public_decrypt(base64_decode($encrypted), $decrypted, self::getPublicKey())) ? $decrypted : null;

    }

}

Class call cases

$rsa = new Rsa();
$data['name'] = 'Tom';
$data['age'] = '20';
$privateEncrypt = $rsa->privateEncrypt(json_encode($data));
echo ' After private key encryption :'.$privateEncrypt.'<br>';
$publicDecrypt = $rsa->publicDecrypt($privateEncrypt);
echo ' After public key decryption :'.$publicDecrypt.'<br>';


$publicEncrypt = $rsa->publicEncrypt(json_encode($data));
echo ' After public key encryption :'.$publicEncrypt.'<br>';
$privateDecrypt = $rsa->privateDecrypt($publicEncrypt);
echo ' After decrypting the private key :'.$privateDecrypt;