openssl_seal

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

openssl_seal — Seal (encrypt) data

说明

int openssl_seal ( string $data , string &$sealed_data , array &$env_keys , array $pub_key_ids [, string $method = "RC4" [, string &$iv ]] )

openssl_seal() seals (encrypts) data by using the given method with a randomly generated secret key. The key is encrypted with each of the public keys associated with the identifiers in pub_key_ids and each encrypted key is returned in env_keys. This means that one can send sealed data to multiple recipients (provided one has obtained their public keys). Each recipient must receive both the sealed data and the envelope key that was encrypted with the recipient's public key.

参数

data: The data to seal.
sealed_data: The sealed data.
env_keys: Array of encrypted keys.
pub_key_ids: Array of public key resource identifiers.
method: The cipher method.
iv: The initialization vector.

返回值

Returns the length of the sealed data on success, or FALSE on error. If successful the sealed data is returned in sealed_data, and the envelope keys in env_keys.

更新日志

版本	说明
7.0.0	The `iv` has been added.
5.3.0	The `method` has been added.

范例

Example #1 openssl_seal() example


<?php
// $data is assumed to contain the data to be sealed

// fetch public keys for our recipients, and ready them
$fp = fopen("/src/openssl-0.9.6/demos/maurice/cert.pem", "r");
$cert = fread($fp, 8192);
fclose($fp);
$pk1 = openssl_get_publickey($cert);
// Repeat for second recipient
$fp = fopen("/src/openssl-0.9.6/demos/sign/cert.pem", "r");
$cert = fread($fp, 8192);
fclose($fp);
$pk2 = openssl_get_publickey($cert);

// seal message, only owners of $pk1 and $pk2 can decrypt $sealed with keys
// $ekeys[0] and $ekeys[1] respectively.
openssl_seal($data, $sealed, $ekeys, array($pk1, $pk2));

// free the keys from memory
openssl_free_key($pk1);
openssl_free_key($pk2);
?>

更新日志

版本	说明
5.3.0	The `method` parameter was added.

参见

openssl_open() - Open sealed data

User Contributed Notes

amer.alhabsi AT gmail DOT com 28-May-2016 04:58


while the default is using RC4, it is possible to use other more secure algorithms. These are specified as the fifth parameter. Also, one needs to add an initialization vector (random bytes). Eg.



<?php

    $data = "This is top secret.";

    // fetch public keys for our recipients, and ready them

    $cert = file_get_contents('./cert.pem');



    $pk1 = openssl_get_publickey($cert);

    $iv = openssl_random_pseudo_bytes(32);

    openssl_seal($data, $sealed, $ekeys, array($pk1), "AES256", $iv);



    // free the keys from memory

    openssl_free_key($pk1);

    echo base64_encode($sealed);

?>

bowfingermail at gmx dot net 24-Oct-2015 11:52


According to several sources (e.g. crypto101.io or Wikipedia) RC4 is not safe and not supposed to be used anymore.

So, shouldn't openssl_seal use another stream cipher in place of RC4?

hfuecks at nospam dot org 29-Oct-2007 04:44


openssl_seal() can work well when you need to pass data securely to other platforms / languages. What openssl_seal() does is;



1. Generate a random key

2. Encrypt the data symmetrically with RC4 using the random key

3. Encrypt the random key itself with RSA using the public key / certificate

4. Returns the encrypted data and the encrypted key



So to decrypt the steps are simply;



1. Decrypt the key using RSA and your private key

2. Decrypt the data using RC4 and the decrypted key



The trickiest part may be figuring out how handle the private key - BouncyCastle ( http://www.bouncycastle.org/ ) provides a PEMReader for Java and C# while Not Yet commons-ssl ( http://juliusdavies.ca/commons-ssl/ ) has a KeyStoreBuilder to build Java keystores out of a PEM certificate.



A complete example in Java is described at http://blog.local.ch/archive/2007/10/29/openssl-php-to-java.html

devel@no-spam 15-Jun-2005 03:20


"seals (encrypts) data by using RC4 with a randomly generated secret key"

It should be noted that the randomly generated secret key is 128 bits long (openssl: EVP_rc4(void):  RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.)