PHP RSA Encryption Logic - php

Question

I need to send a password that's RSA encrypted with a public key (along with some other data). Here are the exact instructions from the documentation for the password:
Encode password in Base64 and ensure UTF-8 encoding
Encrypt password with RSA with provided public key, no block mode, and PKCS1Padding
Encode resulting encryption in Base64 with ensured UTF-8 encoding
Here's the code I'm using that to me seems correct:
function encryptPassword($pass) {
$pass = base64_encode($pass);
$fp = fopen("./cert.crt", "r");
$publicKey = fread($fp, 8192);
fclose($fp);
openssl_get_publickey($publicKey);
openssl_public_encrypt($pass, $cryptedText, $publicKey, OPENSSL_PKCS1_PADDING);
return base64_encode(utf8_encode($cryptedText));
}
I'm getting an error on the other side saying the password can't be decoded. Support from them is basically non-existent other than the error message, and them saying everything is correct on their side. My question is, am I sending what they're asking for according to the documentation?
Thanks in advance!

Answer 1

No, you've taken Base64 with ensured UTF-8 encoding too literally. utf8_encode transforms one textual encoding into another, but $cryptedText is not textual. It is a binary string, so you lose some characters during encoding. Simply remove it, because Base64 gives you already a textual representation of the binary data:
return base64_encode($cryptedText);
Additionally, you probably wanted to pass the public key resource into the encryption function:
$key_resource = openssl_get_publickey($publicKey);
openssl_public_encrypt($pass, $cryptedText, $key_resource, OPENSSL_PKCS1_PADDING);