(PHP 5 >= 5.2.2)
openssl_pkcs12_export_to_file — Exports a PKCS#12 Compatible Certificate Store File
$x509
   , string $filename
   , mixed $priv_key
   , string $pass
   [, array $args
  ] )
   openssl_pkcs12_export_to_file() stores
   x509 into a file named by
   filename in a PKCS#12 file format.
  
x509See Key/Certificate parameters for a list of valid values.
filenamePath to the output file.
priv_keyPrivate key component of PKCS#12 file.
passEncryption password for unlocking the PKCS#12 file.
args
   Returns TRUE on success or FALSE on failure.