adds .local/share/millennium and easyeffects

.local/share/millennium/plugins/extendium/backend/install_extension/hmac.lua

@@ -0,0 +1,67 @@
+-- HMAC Context for computing MACs on Chrome preferences
+
+local logger = require("logger")
+local json_helpers = require("install_extension.json_helpers")
+local sha2 = require("install_extension.sha2")
+
+---@class HmacContext
+---@field sid string
+---@field seed_hex string
+---@field seed_bytes string
+local HmacContext = {}
+HmacContext.__index = HmacContext
+
+---@param sid string
+---@param seed_hex string
+---@return HmacContext
+function HmacContext.new(sid, seed_hex)
+    local self = setmetatable({}, HmacContext)
+    self.sid = sid or ""
+    self.seed_hex = seed_hex or "" -- Empty for Steam CEF
+    self.seed_bytes = sha2.hex_to_bin(seed_hex or "")
+    return self
+end
+
+---@param json_path string
+---@param value any
+---@return string|nil
+function HmacContext:compute_mac(json_path, value)
+    local cleaned = json_helpers.remove_empty_children(value)
+    -- Use sorted JSON for consistent key ordering (must match JS JSON.stringify)
+    local json_value = json_helpers.encode_sorted(cleaned)
+    json_value = json_helpers.escape_for_hmac(json_value)
+
+    local message = self.sid .. json_path .. json_value
+    logger:info("[install] Computing MAC for path: " .. json_path)
+    logger:info("[install] Message length: " .. #message)
+    logger:info("[install] JSON preview: " .. json_value:sub(1, 100) .. "...")
+
+    local mac = string.upper(sha2.hmac(sha2.sha256, self.seed_bytes, message))
+    if mac then
+        logger:info("[install] MAC: " .. mac:sub(1, 16) .. "...")
+    else
+        logger:error("[install] MAC computation returned nil!")
+    end
+    return mac
+end
+
+---@param macs table
+---@return string|nil
+function HmacContext:compute_super_mac(macs)
+    -- Use sorted JSON for consistent key ordering
+    local macs_json = json_helpers.encode_sorted(macs)
+    local message = self.sid .. macs_json
+
+    logger:info("[install] Computing super MAC...")
+    logger:info("[install] MACs JSON: " .. macs_json:sub(1, 100) .. "...")
+
+    local mac = string.upper(sha2.hmac(sha2.sha256, self.seed_bytes, message))
+    if mac then
+        logger:info("[install] Super MAC: " .. mac:sub(1, 16) .. "...")
+    else
+        logger:error("[install] Super MAC computation returned nil!")
+    end
+    return mac
+end
+
+return HmacContext