(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
openssl_pkey_export — Gets an exportable representation of a key into a string
$key,&$output,$passphrase = null,$options = null
   openssl_pkey_export() exports
   key as a PEM encoded string and stores it into
   output (which is passed by reference).
  
Note: You need to have a valid openssl.cnf installed for this function to operate correctly. See the notes under the installation section for more information.
key
output
passphrase
       The key is optionally protected by passphrase.
      
options
       options can be used to fine-tune the export
       process by specifying and/or overriding options for the openssl
       configuration file.  See openssl_csr_new() for more
       information about options.
      
   Returns true on success or false on failure.
  
| Version | Description | 
|---|---|
| 8.0.0 | keyaccepts an OpenSSLAsymmetricKey
       or OpenSSLCertificate instance now;
       previously, a resource of typeOpenSSL keyorOpenSSL X.509was accepted. |