I can do that : Encrypt on frontend (sodium-plus.js) with public-key from backend (PHP sodium)
But I want to do the contrary (encrypt with php, decrypt with javascript), and I have an issue.
I can get my private key from my html page (generated with php) as a hex string ( sodium_bin2hex(sodium_crypto_secretbox_keygen()) ), but I can't use it with sodium plus.
I know this code to get public key :
let key = X25519PublicKey.from('...', "hex");
but in my case that doesn't work and I have an error passing this variable in
await sodium.crypto_secretbox_open(text, nonce, key);
I've tried just with the hex string convert to bin ( await sodium.sodium_hex2bin(key) ) but it doesn't work too.
Here is my code :
define(function (require) {
const { SodiumPlus } = require("sodium-plus");
});
let sodium;
(async function () {
if (!sodium) sodium = await SodiumPlus.auto();
let text = "...";//my text + nonce (at the end) in hex
let nonce = text.substr(-48);
text = text.substr(0, text.length - 48);
let key = X25519PublicKey.from($("#key").text(), "hex");//get my private key in hex, on my html page
text = await sodium.sodium_hex2bin(text);
nonce = await sodium.sodium_hex2bin(nonce);
let output = await sodium.crypto_secretbox_open(text, nonce, key);
console.log(output.toString());
})();
thank you
Here is my solution with crypto_box and secret and public twice :
define(function (require) {
const { SodiumPlus } = require("sodium-plus");
});
let sodium;
(async function () {
if (!sodium) sodium = await SodiumPlus.auto();
let text = ""; //string in hex to be decrypted (see below for my php code server side)
let nonce = text.substring(text.length -48); //nonce at the end of the string
nonce = await sodium.sodium_hex2bin(nonce); //nonce hex to bin
text = text.substring(0, text.length - 48); //text without nonce
text = await sodium.sodium_hex2bin(text); //text hex to bin
let publicKey = $("#key").text(); //to get my key in hex from my html page (key = secret key + public key), see below my php code $decryption_key
let secretKey = publicKey.substring(0, 64);//to get the public key in hex
secretKey = X25519SecretKey.from(secretKey, "hex"); //public key hex to array bin
publicKey = publicKey.substring(publicKey.length -64); //same for public key
publicKey = X25519PublicKey.from(publicKey, "hex");
let output = await sodium.crypto_box_open(text, nonce, secretKey, publicKey);
output = output.toString(); // bin to string
console.log(output);
})();
Here is my php code to encrypt, for example :
$text = '...'; //text to encrypt
$key = sodium_hex2bin( '...' ); //key in hex (got from an other code, see below $encryption_key)
$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
$text_encrypt = sodium_crypto_box($text, $nonce, $key);
$text_encrypt = sodium_bin2hex($text_encrypt.$nonce);
return $text_encrypt;
My php code for encryption key in php, and decryption key on my html page (then got by javascript)
$keypair1 = sodium_crypto_box_keypair();
$keypair1_secret = sodium_crypto_box_secretkey($keypair1);
$keypair1_public = sodium_crypto_box_publickey($keypair1);
$keypair2 = sodium_crypto_box_keypair();
$keypair2_secret = sodium_crypto_box_secretkey($keypair2);
$keypair2_public = sodium_crypto_box_publickey($keypair2);
$encryption_key = sodium_crypto_box_keypair_from_secretkey_and_publickey($keypair1_secret, $keypair2_public);
$encryption_key = sodium_bin2hex( $encryption_key ); //for my php encrypt code
$decryption_key = sodium_crypto_box_keypair_from_secretkey_and_publickey($keypair2_secret, $keypair1_public);
$decryption_key = sodium_bin2hex( $decryption_key ); //for my html page, then got by javascript