refactor: harden client runtime and exports

_Core/security/SecureSessionStore.gd

@@ -0,0 +1,130 @@
+extends RefCounted
+
+const STORAGE_VERSION: int = 2
+const BLOCK_SIZE: int = 16
+const KEY_CONTEXT: String = "WhaleTown-V2/session-store/v1"
+
+func save_refresh_token(path: String, refresh_token: String) -> bool:
+	if refresh_token.is_empty():
+		clear(path)
+		return true
+	var keys := _derive_keys()
+	if keys.is_empty():
+		return false
+	var iv := Crypto.new().generate_random_bytes(BLOCK_SIZE)
+	var encryption_key: PackedByteArray = keys.get("encryption", PackedByteArray())
+	var authentication_key: PackedByteArray = keys.get("authentication", PackedByteArray())
+	var encrypted := _encrypt(refresh_token.to_utf8_buffer(), encryption_key, iv)
+	if encrypted.is_empty():
+		return false
+	var authenticated_data := iv.duplicate()
+	authenticated_data.append_array(encrypted)
+	var mac := Crypto.new().hmac_digest(HashingContext.HASH_SHA256, authentication_key, authenticated_data)
+	var payload := {
+		"version": STORAGE_VERSION,
+		"iv": Marshalls.raw_to_base64(iv),
+		"ciphertext": Marshalls.raw_to_base64(encrypted),
+		"mac": Marshalls.raw_to_base64(mac),
+		"saved_at": Time.get_unix_time_from_system(),
+	}
+	var file := FileAccess.open(path, FileAccess.WRITE)
+	if file == null:
+		return false
+	file.store_string(JSON.stringify(payload))
+	file.close()
+	return true
+
+func load_refresh_token(path: String) -> String:
+	if not FileAccess.file_exists(path):
+		return ""
+	var keys := _derive_keys()
+	if keys.is_empty():
+		clear(path)
+		return ""
+	var json := JSON.new()
+	if json.parse(FileAccess.get_file_as_string(path)) != OK or not (json.data is Dictionary):
+		clear(path)
+		return ""
+	var payload: Dictionary = json.data
+	if int(payload.get("version", 0)) != STORAGE_VERSION:
+		clear(path)
+		return ""
+	var iv := Marshalls.base64_to_raw(str(payload.get("iv", "")))
+	var encrypted := Marshalls.base64_to_raw(str(payload.get("ciphertext", "")))
+	var expected_mac := Marshalls.base64_to_raw(str(payload.get("mac", "")))
+	if iv.size() != BLOCK_SIZE or encrypted.is_empty() or expected_mac.is_empty():
+		clear(path)
+		return ""
+	var authenticated_data := iv.duplicate()
+	authenticated_data.append_array(encrypted)
+	var encryption_key: PackedByteArray = keys.get("encryption", PackedByteArray())
+	var authentication_key: PackedByteArray = keys.get("authentication", PackedByteArray())
+	var actual_mac := Crypto.new().hmac_digest(HashingContext.HASH_SHA256, authentication_key, authenticated_data)
+	if not _constant_time_equals(actual_mac, expected_mac):
+		clear(path)
+		return ""
+	var decrypted := _decrypt(encrypted, encryption_key, iv)
+	return decrypted.get_string_from_utf8().strip_edges()
+
+func clear(path: String) -> void:
+	if FileAccess.file_exists(path):
+		DirAccess.remove_absolute(ProjectSettings.globalize_path(path))
+
+func _derive_keys() -> Dictionary:
+	if OS.get_name() == "Web":
+		return {}
+	var device_id := OS.get_unique_id().strip_edges()
+	if device_id.is_empty():
+		return {}
+	var root_key := _sha256((KEY_CONTEXT + ":" + device_id).to_utf8_buffer())
+	if root_key.is_empty():
+		return {}
+	return {
+		"encryption": _sha256(root_key + ":encryption".to_utf8_buffer()),
+		"authentication": _sha256(root_key + ":authentication".to_utf8_buffer()),
+	}
+
+func _sha256(bytes: PackedByteArray) -> PackedByteArray:
+	var hash_context := HashingContext.new()
+	if hash_context.start(HashingContext.HASH_SHA256) != OK:
+		return PackedByteArray()
+	if hash_context.update(bytes) != OK:
+		return PackedByteArray()
+	return hash_context.finish()
+
+func _encrypt(plain_text: PackedByteArray, key: PackedByteArray, iv: PackedByteArray) -> PackedByteArray:
+	var padded := plain_text.duplicate()
+	var padding_size := BLOCK_SIZE - (padded.size() % BLOCK_SIZE)
+	for _index in range(padding_size):
+		padded.append(padding_size)
+	var aes := AESContext.new()
+	if aes.start(AESContext.MODE_CBC_ENCRYPT, key, iv) != OK:
+		return PackedByteArray()
+	var encrypted := aes.update(padded)
+	aes.finish()
+	return encrypted
+
+func _decrypt(encrypted: PackedByteArray, key: PackedByteArray, iv: PackedByteArray) -> PackedByteArray:
+	var aes := AESContext.new()
+	if aes.start(AESContext.MODE_CBC_DECRYPT, key, iv) != OK:
+		return PackedByteArray()
+	var padded := aes.update(encrypted)
+	aes.finish()
+	if padded.is_empty():
+		return PackedByteArray()
+	var padding_size := int(padded[padded.size() - 1])
+	if padding_size < 1 or padding_size > BLOCK_SIZE or padding_size > padded.size():
+		return PackedByteArray()
+	for index in range(padded.size() - padding_size, padded.size()):
+		if int(padded[index]) != padding_size:
+			return PackedByteArray()
+	padded.resize(padded.size() - padding_size)
+	return padded
+
+func _constant_time_equals(left: PackedByteArray, right: PackedByteArray) -> bool:
+	if left.size() != right.size():
+		return false
+	var difference := 0
+	for index in range(left.size()):
+		difference |= int(left[index]) ^ int(right[index])
+	return difference == 0

_Core/security/SecureSessionStore.gd.uid

@@ -0,0 +1 @@
+uid://bqd3tfgvlhj8r