171 lines
No EOL
4.6 KiB
Lua
171 lines
No EOL
4.6 KiB
Lua
-- 游戏专用解密模块（GB2312/ANSI兼容版）
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-- 适用于游戏Lua环境，精简且高效
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GameCrypto = {}
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-- Base64解码表
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local base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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local base64_lookup = {}
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for i = 1, 64 do
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base64_lookup[base64_chars:sub(i, i)] = i - 1
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end
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-- 兼容的位异或运算函数
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local function bit_xor(a, b)
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-- 确保参数为整数且在0-255范围内
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a = math.floor(a) % 256
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b = math.floor(b) % 256
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-- 如果有内置的位运算，优先使用
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if bit and bit.bxor then
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return bit.bxor(a, b)
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elseif bit32 and bit32.bxor then
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return bit32.bxor(a, b)
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else
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-- 手动实现位异或
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local result = 0
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local power = 1
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while a > 0 or b > 0 do
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local bit_a = a % 2
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local bit_b = b % 2
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if bit_a ~= bit_b then
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result = result + power
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end
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a = math.floor(a / 2)
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b = math.floor(b / 2)
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power = power * 2
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end
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return result
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end
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end
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-- Base64解码函数
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local function base64_decode(data)
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data = string.gsub(data, "[^A-Za-z0-9+/=]", "")
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local bytes = {}
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for i = 1, #data, 4 do
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local c1 = data:sub(i, i)
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local c2 = data:sub(i + 1, i + 1) or '='
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local c3 = data:sub(i + 2, i + 2) or '='
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local c4 = data:sub(i + 3, i + 3) or '='
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if not (base64_lookup[c1] and base64_lookup[c2]) then break end
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local chunk = base64_lookup[c1] * 262144 +
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base64_lookup[c2] * 4096 +
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(c3 ~= '=' and base64_lookup[c3] or 0) * 64 +
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(c4 ~= '=' and base64_lookup[c4] or 0)
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table.insert(bytes, math.floor(chunk / 65536) % 256)
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if c3 ~= '=' then
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table.insert(bytes, math.floor(chunk / 256) % 256)
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end
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if c4 ~= '=' then
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table.insert(bytes, chunk % 256)
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end
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end
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return bytes
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end
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-- 密钥扩展算法
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local function expand_key(key, text_len)
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local expanded = {}
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local key_len = #key
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for i = 1, text_len + 8 do
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local pos = (i - 1) % key_len + 1
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local k_byte = key:byte(pos)
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local p_byte = key:byte(((i - 1) * 167 + 113) % key_len + 1)
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-- 与Python完全一致的计算
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local mixed = (k_byte * 131 + p_byte * 241 + i * 97 + key_len * 47) % 256
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expanded[i] = mixed
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end
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return expanded
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end
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-- 解密单个字节
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local function mix_decrypt(enc_byte, key_byte, position)
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local original = enc_byte
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-- 严格按照加密的逆序操作，使用兼容的位运算
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-- 第4步逆操作：original ^ ((key_byte * 5 + position * 13) % 256)
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local xor_val = (key_byte * 5 + position * 13) % 256
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original = bit_xor(original, xor_val)
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-- 第3步逆操作：(original - position * 11 + 256) % 256
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original = (original - position * 11 + 256) % 256
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-- 第2步逆操作：original ^ ((key_byte + position * 7) % 256)
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xor_val = (key_byte + position * 7) % 256
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original = bit_xor(original, xor_val)
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-- 第1步逆操作：(original - key_byte * 3 - position * 5 + 256) % 256
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original = (original - key_byte * 3 - position * 5 + 256) % 256
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return original
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end
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-- 字节数组转字符串（通用版本）
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local function bytes_to_string(bytes_list)
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-- 直接将字节转换为字符串，不做特殊处理
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-- 让游戏端根据自己的字符集来正确显示
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local result = ""
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for _, b in ipairs(bytes_list) do
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if b >= 0 and b <= 255 then
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result = result .. string.char(b)
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end
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end
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return result
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end
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-- 主解密函数（游戏专用）
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function GameCrypto.decrypt(encrypted_base64, key)
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-- 参数验证
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if type(encrypted_base64) ~= "string" or #encrypted_base64 == 0 then
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return ""
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end
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if type(key) ~= "string" or #key == 0 then
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return ""
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end
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-- Base64解码
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local encrypted_bytes = base64_decode(encrypted_base64)
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if not encrypted_bytes or #encrypted_bytes < 8 then
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return ""
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end
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-- 提取数据部分（跳过前8字节前缀）
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local text_bytes = {}
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for i = 9, #encrypted_bytes do
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text_bytes[i - 8] = encrypted_bytes[i]
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end
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if #text_bytes == 0 then
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return ""
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end
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-- 扩展密钥
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local expanded_key = expand_key(key, #text_bytes)
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-- 解密处理（修正索引计算）
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local decrypted_bytes = {}
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for i = 1, #text_bytes do
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local key_idx = i % #expanded_key
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if key_idx == 0 then key_idx = #expanded_key end
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decrypted_bytes[i] = mix_decrypt(text_bytes[i], expanded_key[key_idx], i)
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end
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-- 转换为字符串（通用方式）
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return bytes_to_string(decrypted_bytes)
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end
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return GameCrypto |