How to encrypt and decrypt data in PHP?

PHP is an open source server-side programming language that is widely used in the field of web development. Since web applications often involve users' sensitive information, such as passwords, bank card numbers, etc., it is particularly important to encrypt and decrypt this information.

This article will introduce how to encrypt and decrypt data in PHP, mainly including the following content:

1. Commonly used encryption algorithms and their characteristics
2. Used in PHP MD5 encryption
3. Use sha1 encryption in PHP
4. Use base64 encoding in PHP
5. Use openssl extension library in PHP for AES encryption and decryption
6. Steps to use the mcrypt extension library for AES encryption and decryption in PHP

1. Commonly used encryption algorithms and their characteristics

1. MD5 algorithm: a commonly used message digest The algorithm maps a string of any length into a 128-bit output value and is widely used in fields such as data encryption and electronic signatures.

Features: The MD5 algorithm is irreversible, that is, the input value cannot be inferred from the output value; the MD5 algorithm ensures that the output value of the same input is the same; the MD5 algorithm is easily cracked by collision attacks.

2. SHA1 algorithm: A secure hash algorithm, similar to MD5, that maps a string of any length into a 160-bit output value and has good security and anti-collision capabilities.

Features: The SHA1 algorithm is irreversible; the output value length of the SHA1 algorithm is longer than the MD5 algorithm, ensuring better security; the SHA1 algorithm cannot completely prevent collision attacks.

3. base64 encoding: An encoding method that encodes binary data into highly readable ASCII characters. It is widely used in email, HTTP protocols and other fields.

Features: base64 encoding is not a real encryption algorithm, but an encoding method; base64 encoding does not change the content of the data, but only changes the representation of the data; base64 encoding can increase the stability of data transmission and security.

4. AES algorithm: Advanced Encryption Standard is a symmetric encryption algorithm used to protect the security of data such as sensitive information. The AES algorithm is divided into three key lengths: 128 bits, 192 bits and 256 bits.

Features: The AES algorithm is symmetric encryption, and the same key is used for encryption and decryption; the AES algorithm has better security and efficiency; the longer the key length used by the AES algorithm, the higher the security .

2. Use MD5 encryption in PHP

Use the md5() function in PHP to encrypt strings with MD5. The sample code is as follows:

$str = "hello world";
$encrypted_str = md5($str);
echo $encrypted_str;

The output result is:

5eb63bbbe01eeed093cb22bb8f5acdc3

3. Use sha1 encryption in PHP

Use the sha1() function in PHP to SHA1 encrypt strings. The sample code is as follows:

$str = "hello world";
$encrypted_str = sha1($str);
echo $encrypted_str;

The output result is ：

2ef7bde608ce5404e97d5f042f95f89f1c232871

4. Use base64 encoding in PHP

Use the base64_encode() function in PHP to base64-encode a string, and use the base64_decode() function to base64-encode the string. Decoding, the sample code is as follows:

$str = "hello world";
$encoded_str = base64_encode($str);
echo $encoded_str . "
";  // 输出：aGVsbG8gd29ybGQ=
$decoded_str = base64_decode($encoded_str);
echo $decoded_str;    // 输出：hello world

5. Use the openssl extension library in PHP for AES encryption and decryption

Use the openssl extension library in PHP to perform AES encryption and decryption of data, sample code As follows:

// AES加密
function encrypt($str, $key) {
    $iv_size = openssl_cipher_iv_length('AES-256-CBC');
    $iv = openssl_random_pseudo_bytes($iv_size);   // 生成随机IV
    $encrypted_str = openssl_encrypt($str, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    $result = base64_encode($iv . $encrypted_str);
    return $result;
}

// AES解密
function decrypt($encrypted_str, $key) {
    $encrypted_str = base64_decode($encrypted_str);
    $iv_size = openssl_cipher_iv_length('AES-256-CBC');
    $iv = substr($encrypted_str, 0, $iv_size);
    $encrypted_str = substr($encrypted_str, $iv_size);
    $result = openssl_decrypt($encrypted_str, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    return $result;
}

// 测试代码
$key = "12345678901234567890123456789012";   // AES密钥，32位
$str = "hello world";
$encrypted_str = encrypt($str, $key);
echo $encrypted_str . "
";
$decrypted_str = decrypt($encrypted_str, $key);
echo $decrypted_str . "
";

The output result is:

7KdkeT91N7zg8WZrZ1Oehg==xsYlbGhMF8dNQXH1LqTwVw==
hello world

6. Steps to use the mcrypt extension library for AES encryption and decryption in PHP

Use the mcrypt extension library for AES encryption and decryption The steps for decryption are as follows:

1. Load the mcrypt extension library

extension_loaded('mcrypt');  // 检查是否已经加载mcrypt扩展库

2. Generate a random IV

$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

3. Use mcrypt_encrypt( ) function for AES encryption

$encrypted_str = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $str, MCRYPT_MODE_CBC, $iv);

4. Use the mcrypt_decrypt() function for AES decryption

$decrypted_str = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $encrypted_str, MCRYPT_MODE_CBC, $iv);

5. Use the base64_encode() function to base64 encode the encrypted data

$encrypted_str = base64_encode($iv . $encrypted_str);

6. Use the substr() function to intercept the IV and ciphertext part of the encrypted data

$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = substr($encrypted_str, 0, $iv_size);
$encrypted_str = substr($encrypted_str, $iv_size);

The complete AES encryption and decryption sample code is as follows:

// AES加密
function encrypt($str, $key) {
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);    // 生成随机IV
    $encrypted_str = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $str, MCRYPT_MODE_CBC, $iv);
    $result = base64_encode($iv . $encrypted_str);    // 对IV和密文进行base64编码
    return $result;
}

// AES解密
function decrypt($encrypted_str, $key) {
    $encrypted_str = base64_decode($encrypted_str);  // 对base64编码的字符串进行解码
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = substr($encrypted_str, 0, $iv_size);       // 截取IV值
    $encrypted_str = substr($encrypted_str, $iv_size);    // 截取密文部分
    $result = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $encrypted_str, MCRYPT_MODE_CBC, $iv);
    return $result;
}

// 测试代码
$key = "1234567890123456";       // AES密钥，16位
$str = "hello world";
$encrypted_str = encrypt($str, $key);
echo $encrypted_str . "
";
$decrypted_str = decrypt($encrypted_str, $key);
echo $decrypted_str . "
";

The output result is:

Ym63V4DnBc/jk9bNNzlngQtdeecbBZ+E7IHvC6khMgg=
hello world

Summary:

The above is the method of data encryption and decryption in PHP. Different encryption algorithms have different characteristics and applicable scenarios. Development Personnel should select an appropriate encryption method based on actual needs and security requirements. While using encryption methods, you also need to pay attention to the security protection of keys and encryption processes to avoid being attacked by hackers.

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