php Encryption/Decryption

by Anish

Posted on Thursday December 13 , 2018

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openssl_encrypt/decrypt

openssl_encrypt: Encrypt the data
openssl_decrypt: Decrypt the data

• Supported PHP Versions (PHP 5 >= 5.3.0, PHP 7)

The Syntax

string openssl_encrypt ( string $data , string $method , string $key [, int $options = 0 [, string $iv = "" [, string $tag = NULL [, string $aad = "" [, int $tag_length = 16 ]]]]] )

string openssl_decrypt ( string $data , string $method , string $key [, int $options = 0 [, string $iv = "" [, string $tag = "" [, string $aad = "" ]]]] )

• data: The plaintext message data to be encrypted.
• method: The cipher method, see openssl_get_cipher_methods() for a list of potential values.
• key : User supplied key
• IV: The Initialization Vector
• AAD: For Authenticated encryption
• Returns: Returns the encrypted string on success or FALSE on failure.

Since block cipher modes of operation require an IV which is random and unpredictable, or at least unique for each message encrypted with a given key. Different block cipher modes have different IV length requirement for example

Cipher Mode	IV Length
aes-128-cbc	16
camellia-192-ofb	16
cast5-cbc	8
bf-cbc	8
aes-256-gcm	12

Examples

A Great Feedback by Michal Špaček

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aes-128-cbc encrypt/decrypt example

Note: AES-CBC mode vulnerable to padding oracle attacks, Kindly Don't use these

/**  
* Created by https://8gwifi.org  
* User: Anish Nath  
* Date: 2018-12-10  
* Time: 15:13  
*/  
  
<?php  
  
// php AES-128-CBC Encryption Example  
$plaintext = "Hello 8gwifi.org";  
$key = "myverystrongpasswordo32bitleng";  
  
$ivlen = openssl_cipher_iv_length($cipher="aes-128-cbc");  
  
//Generate Random IV  
$iv = openssl_random_pseudo_bytes($ivlen);  
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
$ciphertext = base64_encode( $iv.$ciphertext_raw );  
  
echo "Encrypted Text : $ciphertext \n";  
  
//php AES-128-CBC Dec Example  
$c = base64_decode("$ciphertext");  
$ivlen = openssl_cipher_iv_length($cipher="aes-128-cbc");  
$iv = substr($c, 0, $ivlen);  
$ciphertext_raw = substr($c, $ivlen);  
  
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
echo "Decrypted Text: $original_plaintext\n";  
  
?>

The above example will output something similar to:

$ /usr/bin/php aes-128-cbc.php
/**
* Created by https://8gwifi.org
* User: Anish Nath
* Date: 2018-12-10
* Time: 15:13
*/
Encrypted Text : CLBckQqECD15NoXSD3JZGknFlQtpGrYR7BFlUshUZ9t7pMdAz6FAR+dkym46+stX 
Decrypted Text: Hello 8gwifi.org

Process finished with exit code 0

aes-192-cfb encrypt/decrypt example

/**  
* Created by https://8gwifi.org  
* User: Anish Nath  
* Date: 2018-12-10  
* Time: 15:13  
*/  
  
  
<?php  
  
// php AES-192-CBC Encryption Example  
$plaintext = "Hello 8gwifi.org";  
$key = "myverystrongpasswordo32bitlength";  

$ivlen = openssl_cipher_iv_length($cipher="aes-192-cfb");    
//Generate Random IV  
$iv = openssl_random_pseudo_bytes($ivlen);  
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
$ciphertext = base64_encode( $iv.$ciphertext_raw );  
echo "Encrypted Text : $ciphertext \n";  
  
//php AES-192-CBC Dec Example  
$c = base64_decode($ciphertext);  
$ivlen = openssl_cipher_iv_length($cipher="aes-192-cfb");  
$iv = substr($c, 0, $ivlen);  
$ciphertext_raw = substr($c, $ivlen);  
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
echo "Decrypted Text: $original_plaintext\n";  
  
?>

The above example will output something similar to:

$ php aes-192-cfb.php
Encrypted Text : /72Gdi7jAqKVJ7APgtWXPKB+9s3+iS7/vwgOaO5/LEc= 
Decrypted Text: Hello 8gwifi.org

aes-256-ofb encrypt/decrypt example

<?php    
// php AES-256-OFB Dec Example 
$plaintext = "Hello 8gwifi.org";  
$key = "myverystrongpasswordo32bitlength";  
  
$ivlen = openssl_cipher_iv_length($cipher="aes-256-ofb");  
//Generate Random IV  
$iv = openssl_random_pseudo_bytes($ivlen);  
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
$ciphertext = base64_encode( $iv.$ciphertext_raw );  
  
echo "Encrypted Text : $ciphertext \n";  
  
//php AES-256-OFB Dec Example  
$c = base64_decode($ciphertext);  
$ivlen = openssl_cipher_iv_length($cipher="aes-256-ofb");  
$iv = substr($c, 0, $ivlen);  
$ciphertext_raw = substr($c, $ivlen);  
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
echo "Decrypted Text: $original_plaintext\n";  
  
?>

The above example will output something similar to:

$/usr/bin/php aes-256-ofb.php
Encrypted Text : FtsxVyVc5zi/x/1oEpEoaVzNJKw6bYkgDH2kST2PLug= 
Decrypted Text: Hello 8gwifi.org

aes-256-gcm encrypt/decrypt example

Note: AEAD is not supported for all version prior to the PHP 7.1, This example utilizes php 7.1

/**  
* Created by https://8gwifi.org  
* User: Anish Nath  
* Date: 2018-12-10  
* Time: 15:13  
*/  
  
<?php  
  
// php aes-256-gcm Encryption Example  
$plaintext = "Hello 8gwifi.org";  
$key = "myverystrongpasswordo32bitlength";  
$aad = "not secret";  
  
$ivlen = openssl_cipher_iv_length($cipher="aes-256-gcm");  
  
//Generate Random IV  
$iv = openssl_random_pseudo_bytes($ivlen);  
  
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv,$aad);  
  
  
$ciphertext = base64_encode( $iv.$ciphertext_raw );  
  
echo "Encrypted Text : $ciphertext \n";  
  
//php aes-256-gcm Dec Example  
$c = base64_decode($ciphertext);  
$ivlen = openssl_cipher_iv_length($cipher="aes-256-gcm");  
$iv = substr($c, 0, $ivlen);  
$ciphertext_raw = substr($c, $ivlen);  
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv,$aad);  
echo "Decrypted Text: $original_plaintext\n";  
?>

The above example will output something similar to:

$ /bin/php-7.1.19 aes-256-gcm.php 
/**
* Created by https://8gwifi.org
* User: Anish Nath
* Date: 2018-12-10
* Time: 15:13
*/
Encrypted Text : p3pzMb42n03a9GZTwLHHVf2EPT8OcKrbAg/CVQ== 
Decrypted Text: Hello 8gwifi.org

camellia-256-ofb encrypt/decrypt example

/**  
* Created by https://8gwifi.org  
* User: Anish Nath  
* Date: 2018-12-10  
* Time: 15:13  
*/  
  
  
<?php  
  
// php camellia-256-ofb Encryption Example  
$plaintext = "Hello 8gwifi.org";  
$key = "myverystrongpasswordo32bitlength";  
$ivlen = openssl_cipher_iv_length($cipher="camellia-256-ofb");  
  
//Generate Random IV  
$iv = openssl_random_pseudo_bytes($ivlen);  
  
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
$ciphertext = base64_encode( $iv.$ciphertext_raw );  
  
echo "Encrypted Text : $ciphertext \n";  
  
//php camellia-256-ofb Dec Example  
$c = base64_decode($ciphertext);  
$ivlen = openssl_cipher_iv_length($cipher="camellia-256-ofb");  
$iv = substr($c, 0, $ivlen);  
$ciphertext_raw = substr($c, $ivlen);  
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);  
  
echo "Decrypted Text: $original_plaintext\n";  
  
?>

The above example will output something similar to:

/usr/bin/php camellia-256-ofb.php
Encrypted Text : AgSQP79ml7W/sTBWdtmzkQRgMc8R2L2Nm3LnrOC2+xc= 
Decrypted Text: Hello 8gwifi.org

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