openssl_private_decrypt

ittasks at gmail dot com (2013-04-03 22:17:46)

//if you want to encrypt data without knowing the password so it only be accessible to admin (like storing CC data) - here is one of the ways to do that.
$fnm="test";//path to the file name (.key and .pem)
echo "<form method=post action=".$_SERVER['PHP_SELF']."><table>";
$pass=$_REQUEST['pass'];
$msg=$_REQUEST['msg'];
$genkey=((isset($_REQUEST['go']))?intval("0".$_REQUEST['genkey']):1);
echo "<tr><td>Admin Password :</td><td><input type=text name=pass value=\"$pass\"></td></tr>\n";
echo "<tr><td>Generate New Keys?</td><td><input type=checkbox name=genkey value=1".($genkey?" checked":"")."> Yes</td></tr>\n";
echo "<tr><td colspan=2 align=left>Message:<br><textarea cols=50 name=msg>$msg</textarea></td></tr>\n";
echo "<tr><td colspan=2><input type=submit name='go' value='Go'></td></tr>";
echo "</table></form>";
if($_REQUEST['go']=='Go')
{
$pass=$_REQUEST['pass'];
$msg=$_REQUEST['msg'];
//this you have to only run once ...
if($genkey)
{
echo "<br>generating public/private keys using supplied password...";
exec("openssl req -x509 -passout pass:$pass -newkey rsa:1024 -keyout $fnm.key -out $fnm.pem -subj \"/C=US/ST=California/L=Remote/O=blabla/OU=blabla/CN=user/emailAddress=user@domain.com\"");
}
// or in case if you want to change admin password you need to generate new keys with new password
// and run a script that will take all encrypted data from database, decrypt with old private key and re-encrypt with new private key
echo "<br>Source file: $fnm.pem";
openssl_public_encrypt(urlencode($msg), $encbinary, "file://$fnm.pem"); //no password usage here
$encmsg=base64_encode($encbinary); //ready to be send or stored in DB
echo "<br><br>Encrypted message:<pre>$encmsg</pre>";
echo "<br><br>Decrypting using private key with password...<br>";
if(($prvkey = openssl_pkey_get_private("file://$fnm.key",$pass))===false)
echo "<br><b style='color:red'>Password is incorrect, aborting.</b>";
else
{
openssl_private_decrypt(base64_decode($encmsg),$decmsg,$prvkey);
echo "<br>Decrypted message:<br>".urldecode($decmsg);
}
}

sevaa at sprynet dot com (2009-10-02 19:08:15)

When used with RSA, this function only accepts a single block. Block size is equal to the RSA key size - i. e., with a 1024-bit key, block size should be 128 bytes. Depending on the padding scheme, the payload may be even smaller. The padding is removed, so you'll receive the ready to use plaintext. Blocking logic is up to the caller, though.
When passing Microsoft CryptoAPI-generated RSA cyphertext, revert the bytes in the block (you may use strrev()).

wfredkNOSPAM at L5DevelopmentNOSPAM dot com (2002-03-08 15:58:44)

Encrypt using public key, decrypt using private key.

Use this to store stuff in your database: Unless someone
has your private key, the database contents are useless.

Also, use this for sending to a specific individual:  Get
their public key, encrypt the message, only they can use
their private key to decode it.

<?php
echo "Source: $source";
$fp=fopen("/path/to/certificate.crt","r");
$pub_key=fread($fp,8192);
fclose($fp);
openssl_get_publickey($pub_key);
/*
 * NOTE:  Here you use the $pub_key value (converted, I guess)
 */
openssl_public_encrypt($source,$crypttext,$pub_key);
echo "String crypted: $crypttext";

$fp=fopen("/path/to/private.key","r");
$priv_key=fread($fp,8192);
fclose($fp);
// $passphrase is required if your key is encoded (suggested)
$res = openssl_get_privatekey($priv_key,$passphrase);
/*
 * NOTE:  Here you use the returned resource value
 */
openssl_private_decrypt($crypttext,$newsource,$res);
echo "String decrypt : $newsource";
?>