feature: switch to json serialisation for language interoperability

Author: Greg Bowler

src/Authenticator.php

@@ -137,12 +137,12 @@ private function completeAuth():void {
 		$secretSessionIv = $token->getSecretIv();
 		$encrypted = new EncryptedMessage($queryData, $secretSessionIv);
 		$key = new Key($this->clientKey);
-		$decrypt = $encrypted->decrypt($key);
-		parse_str($decrypt, $data);
+		$decrypted = $encrypted->decrypt($key);
+		$data = json_decode($decrypted);
 		$userData = new UserResponseData(
-			$data["id"],
-			$data["email"],
-			$data["kvp"] ?? [],
+			$data->{"id"},
+			$data->{"email"},
+			$data->{"kvp"} ?? [],
 		);
 
 		$this->session->set(

test/phpunit/AuthenticatorTest.php

@@ -200,7 +200,7 @@ public function testCompleteAuthNotLoggedIn() {
 	public function testCompleteAuth() {
 		$keyBytes = str_repeat("0", SODIUM_CRYPTO_SECRETBOX_KEYBYTES);
 		$ivBytes = str_repeat("1", SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
-		$plainTextMessage = http_build_query([
+		$plainTextMessage = json_encode([
 			"id" => 123,
 			"email" => "[email protected]",
 		]);