Question

Long time listener/first time caller

I have set up a test page as follows

<form action="" method="post">
<input type="text" name="value" width="20" max="30" value=""/>
<input type="submit" value="go"/>
</form>

with some PHP to encrypt the post data “value” and store it in a variable like so

$pubKey = openssl_pkey_get_public(".../public.pem");
openssl_public_encrypt($_POST["value"], $var, $pubKey);

echo $var;

also have tried

$publicKey = ".../public.pem";
$plaintext = $_POST['value'];

openssl_public_encrypt($plaintext, $encrypted, $publicKey);

echo $encrypted;

Keep getting the error

Warning: openssl_public_encrypt() [function.openssl-public-encrypt]: key parameter is not a valid public key

I created the keys with openssl using:

# generate a 1024 bit rsa private key, ask for a passphrase to encrypt it and save to file
openssl genrsa -des3 -out /path/to/privatekey 1024

# generate the public key for the private key and save to file

openssl rsa -in /path/to/privatekey -pubout -out /path/to/publickey

from this website http://andytson.com/blog/2009/07/php-public-key-cryptography-using-openssl/

also tried creating a key with this method:

openssl req \
  -x509 -nodes -days 365 \
  -newkey rsa:1024 -keyout mycert.pem -out mycert.pem

still same error. Sorry but the whole encryption this is cryptic to me. also not very familiar with openssl so code examples would be great.

Answer 1

Your paths appear to be incorrect:

$pubKey = openssl_pkey_get_public(".../public.pem");

and

$publicKey = ".../public.pem";

Should be

$publicKey = "../public.pem";
$pubKey = openssl_pkey_get_public("../public.pem");

If the .pem file is in the parent directory, or:

$publicKey = "./public.pem";
$pubKey = openssl_pkey_get_public("./public.pem");

if the .pem file is in the current working directory. Alternately, you can use absolute paths to be sure you are grabbing the correct file.