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openssl_sealSeal (encrypt) data


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

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.



The data to seal.


The sealed data.


Array of encrypted keys.


Array of public key resource identifiers.


The cipher method.

Valorile întoarse

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.


Example #1 openssl_seal() example

// $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");
$cert fread($fp8192);
$pk1 openssl_get_publickey($cert);
// Repeat for second recipient
$fp fopen("/src/openssl-0.9.6/demos/sign/cert.pem""r");
$cert fread($fp8192);
$pk2 openssl_get_publickey($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

Istoricul schimbărilor

Versiune Descriere
5.3.0 The method parameter was added.

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User Contributed Notes 4 notes

amer.alhabsi AT gmail DOT com
8 months ago
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.

= "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
bowfingermail at gmx dot net
1 year ago
According to several sources (e.g. 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?
11 years ago
"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.)
hfuecks at nospam dot org
9 years ago
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 ( ) provides a PEMReader for Java and C# while Not Yet commons-ssl ( ) has a KeyStoreBuilder to build Java keystores out of a PEM certificate.

A complete example in Java is described at
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