ScotlandPHP

openssl_decrypt

(PHP 5 >= 5.3.0, PHP 7)

openssl_decryptDécrypte les données

Description

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

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

Avertissement

Cette fonction n'est pas documentée et seule la liste des arguments est disponible.

Liste de paramètres

data

Les données.

method

La méthode de cipher.

password

Le password.

options

Le paramètre options peut prendre comme valeur OPENSSL_RAW_DATA ou OPENSSL_ZERO_PADDING.

iv

Un vecteur d'initialisation non-nul.

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 method.

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

Historique

Version Description
5.3.3 Le paramètre iv a été ajouté.
5.4.0 Le paramètre raw_output a été changé en options.

Voir aussi

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User Contributed Notes 6 notes

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12
Hernanibus
1 year 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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1
lucianonapoli at yahoo dot it
7 months 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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2
ittasks at gmail dot com
4 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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0
markagius dot co dot uk
6 months 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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-3
Bitbang3r
6 months ago
openssl_decrypt assumes that $data is base64-encoded by default, but $key and $iv (when using AES) must be "raw" byte values.

In other words, assume that $data, $key, and $iv are all base64-encoded strings. Both $key and $iv must be base64-decoded before openssl_decrypt can use them.

Example code:

$ciphertext64 = "gfcC6t1BarndpzMuvYj2JFpWHqlWSJMhTtxPN7QjyEg=";
$key64 = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8=";
$iv64="AAECAwQFBgcICQoLDA0ODw==";

$key = base64_decode($key64, true);
$iv = base64_decode($iv64, true);

$decrypted = openssl_decrypt($ciphertext64, 'aes-256-cbc', $key, 0, $iv);

Other 'gotchas' to keep in mind when cipher is 'aes-256-cbc':

*  strlen($key) SHOULD be 32. PHP will apparently pad the key if necessary, with potentially unpredictable interoperability with other libraries and platforms, and almost certain reduction in cipher strength. Save yourself the headache, and make sure it's EXACTLY 32.

* strlen($iv) MUST be 16. By definition, AES uses 128-bit blocks, regardless of whether the key length is 128, 192, or 256... and iv's length must be precisely equal to that block length.

* Remember... $iv doesn't necessarily have to be SECRET (it's just a salt), but it MUST be cryptographically random AND different EACH TIME you begin a new round of AES encryption ("round" == "one call to openssl_encrypt or equivalent").

* Don't assume that your random numbers are cryptographically secure unless the function guarantees it. In general, PHP's random numbers AREN'T cryptographically secure (at least, not by default, and not unless the server's admin has gone out of his way to try). There's a HUGE difference between numbers that "look random", and numbers that genuinely ARE random, and it can make the difference between robust long-term encryption and mere obfuscation. See openssl_random_pseudo_bytes.

Finally, if you're attempting to use 'aes-256-gcm' (AEAD), search Google for "67304 gcm" to confirm that it's both supported AND known to work in whatever version of PHP you have available.
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-48
Anonymous
3 years ago
If your using windows os, do not use the text inside the "file previewer" pane, as this is a truncated version of the actual encrypted string.

Instead, you need to open the file directly and use the contents there.

The error message I had been getting was:
"error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length"
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