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openssl_decrypt

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

openssl_decryptDéchiffrer les données

Description

openssl_decrypt(
    string $data,
    string $cipher_algo,
    string $passphrase,
    int $options = 0,
    string $iv = "",
    ?string $tag = null,
    string $aad = ""
): string|false

Prend une chaine brute ou base64 encodée et la déchiffre en utilisant la méthode et la clé passées.

Liste de paramètres

data

Le message chiffré à déchiffrer.

cipher_algo

L'algorithme de chiffrement. Pour la liste des algorithmes de chiffrement disponible, utiliser openssl_get_cipher_methods().

passphrase

La clé.

options

Le paramètre options peut prendre comme valeur OPENSSL_RAW_DATA ou OPENSSL_ZERO_PADDING.

iv

Un vecteur d'initialisation non-nul.

tag

La balise d'authentification en mode de chiffrement AEAD. Si elle est incorrecte, l'authentification échoue et la fonction retourne false.

Attention

La longueur de tag n'est pas vérifié par la fonction. C'est la responsabilité de l'appeleur de s'assurer que la longueur du tag correspond à la longueur du tag reçu quand openssl_encrypt() a été appelée. Sinon, le déchiffrement peut réussir si le début du tag donné correspond au début du vrai tag.

aad

Données supplémentaires authentifiées.

Valeurs de retour

La chaine décryptée en cas de succès ou false si une erreur survient.

Erreurs / Exceptions

Émets une erreur de niveau E_WARNING si un algorithme cipher inconnu est passé via cipher_algo.

Émets une erreur de niveau E_WARNING si une valeur vide est passée comme paramètre iv.

Historique

Version Description
8.1.0 tag est désormais nullable.
7.1.0 Les paramètres tag et aad ont été ajoutée.

Voir aussi

add a note

User Contributed Notes 4 notes

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23
Hernanibus
7 years ago
Parameters may seem obvius to some but not for everyone so:

- $data can be as the description says raw or base64. If no $option is set (this is, if value of 0 is passed in this parameter), data will be assumed to be base64 encoded. If parameter OPENSSL_RAW_DATA is set, it will be understood as row data.

- $password (key) is a String of [pseudo] bytes as those generated by the function openssl_random_pseudo_bytes().

- $options as (as for 2016) two possible values OPENSSL_RAW_DATA and OPENSSL_ZERO_PADDING. Setting both can be done by OPENSSL_RAW_DATA|OPENSSL_ZERO_PADDING. If no OPENSSL_ZERO_PADDING is specify, default pading of PKCS#7 will be done as it's been observe by [openssl at mailismagic dot com]'s coment in openssl_encrypt()

- $iv is as in the case of $password, a String of bytes. Its length depends on the algorithm used. May be the best way to generate an $iv is by:

<?php
$iv
= openssl_random_pseudo_bytes(openssl_cipher_iv_length('your algorithm'));// for example you algorithm = 'AES-256-CTR'
?>
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5
lucianonapoli at yahoo dot it
7 years ago
The parameter string $password must be in binary form and is derived from the exadecimal key value.

Example:

encrypting in command line console with openssl
openssl AES-256-CBC -K 5ae1b8a17bad4da4fdac796f64c16ecd -iv 34857d973953e44afb49ea9d61104d8c -in doc.txt -out doc.enc.txt

decripting in php
$key = hex2bin('5ae1b8a17bad4da4fdac796f64c16ecd');
$iv = hex2bin('34857d973953e44afb49ea9d61104d8c');

$output = openssl_decrypt($encstr, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
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1
markagius dot co dot uk
6 years ago
openssl_decrypt(..) works with most but not all method types.
This list can vary, depending on the data (Message) and key (Password) used.

See the following code and edit the $text and $password values.
Code checks if text is the same after encrypting then decrypting it.

Note:
You can still use openssl_encrypt(..) with;
User enters 'Log-in password'
(Encrypted and stored using openssl_encrypt)
Next time.
User logs-in with 'Log-in password'
(Check that encrypted 'Log-in password' = stored data)

<CODE>
// Please edit $password=... and $text=...

$password = "This is a journey into sound";

$text = "";
for($charNo=0; $charNo<=255; $charNo=$charNo+1){
// if($charNo==127) {$charNo=$charNo+1;}
if(!$charNo<127){
// $text = $text."&#x".strtoupper(dechex($charNo)).";";
$text = $text.chr($charNo);
} else {
$text = $text.chr($charNo);
}
}

$text = "This is a test message.";

print "<TABLE BORDER=\"1\">\n";
print "<TR><TD><B>Encryption type:</B></TD><TD><B>String after converting back:</B></TD></TR>\n";
$ciphers = openssl_get_cipher_methods();
for($pointer=0; $pointer<count($ciphers); $pointer=$pointer+1){
$edit = EncryptDecrypt($text, true, $password, $ciphers[$pointer]);
$check = EncryptDecrypt($edit, false, $password, $ciphers[$pointer]);
if($text!=$check){
$info = $check;
print "<TR><TD>".$ciphers[$pointer]."</TD><TD>".$info."</TD></TR>\n";
}
}
print "</TABLE>\n";

function EncryptDecrypt($oldText, $encryptIt=true, $password="PASSWORD", $encryptType=""){
$ciphers = openssl_get_cipher_methods();
$foundEncType = false;
for($pointer=0; $pointer<count($ciphers); $pointer=$pointer+1){
if($ciphers[$pointer]==$encryptType){$foundEncType=true;}
}
if(!$foundEncType){
$encryptType = "RC2-64-CBC"; // Default value used if not set or listed.
}
if($encryptIt){
$newText = openssl_encrypt($oldText,$encryptType,$password);
} else {
$newText = openssl_decrypt($oldText,$encryptType,$password);
}
return $newText;
}
</CODE>
The following (sometimes) don't work:
DES-EDE3-CFB1 (sometimes)
aes-128-gcm
aes-192-gcm
aes-256-gcm
des-ede3-cfb1 (sometimes)
id-aes128-GCM
id-aes192-GCM
id-aes256-GCM
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2
ittasks at gmail dot com
10 years ago
in case that hosting do not provide openssl_encrypt decrypt functions - it could be mimiced via commad prompt executions
this functions will check is if openssl is installed and try to use it by default

function sslPrm()
{
return array("your_password","IV (optional)","aes-128-cbc");
}
function sslEnc($msg)
{
list ($pass, $iv, $method)=sslPrm();
if(function_exists('openssl_encrypt'))
return urlencode(openssl_encrypt(urlencode($msg), $method, $pass, false, $iv));
else
return urlencode(exec("echo \"".urlencode($msg)."\" | openssl enc -".urlencode($method)." -base64 -nosalt -K ".bin2hex($pass)." -iv ".bin2hex($iv)));
}
function sslDec($msg)
{
list ($pass, $iv, $method)=sslPrm();
if(function_exists('openssl_decrypt'))
return trim(urldecode(openssl_decrypt(urldecode($msg), $method, $pass, false, $iv)));
else
return trim(urldecode(exec("echo \"".urldecode($msg)."\" | openssl enc -".$method." -d -base64 -nosalt -K ".bin2hex($pass)." -iv ".bin2hex($iv))));
}

//example of usage:
$r= sslEnc("This is encryption/decryption test!");
echo "<br>\n".$r.":".sslDec($r);
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