游戏文件：
https://tieba.baidu.com/f/good?cid=0&ie=utf-8&kw=霸王的大陆
我想刷一个组合出来，但是靠随机不太可能：
于是就想用修改存档的方式来改下技能。
直接覆盖
首先，刷新前保存一次存档，刷新后再保存一次存档，用 010 对比一下，发现有4处不同，猜想这4处就是储存技能的位置了。
先尝试直接替换第2处不同，看看能够修改第二个技能。记载替换后的存档，失败了，不仅第2个技能没替换，其他的技能也变化了。再重新加载一次，发现技能又不一样了，于是确定是技能数据修改有问题。
所以直接替换是不行的，应该是游戏对技能数据做了校验，发现被修改之后，就又重新随机了。
反编译游戏
该游戏作者在贴吧做了介绍，是使用 godot 做的，查一下官方文档：
https://docs.godotengine.org/en/stable/
看着非常像Unity，解压一下base.apk，看一下asset下的文件结构，发现有个 script 文件夹，里面有很多 .gdc 文件。
网上搜索一下 gdc decompiler：
https://github.com/bruvzg/gdsdecomp
按照项目的说明，直接使用命令反编译 base.apk，再用 code 打开：
非常的nice，gd 是 gdscript，还是能看懂的，与源码几乎没区别了。
查看 sav 存档
游戏的存档，使用 010 打开后，明显可以看出是一个 json 文件：
直接使用 code 打开，定位到之前对比过的有区别的位置：
diy_skills 是做了校验的。我们需要搞定它。
查找 diy_skills 逻辑
安装一下 gdscript 的插件，可以高亮代码。
一通搜索之后，找到如下逻辑：
var encrypted = PoolByteArray(Global.hex_decode(skills))
var sign_version = encrypted[encrypted.size() - 1]
var signed_len = encrypted[encrypted.size() - 2]
var signed = encrypted.subarray(encrypted.size() - signed_len - 2, encrypted.size() - 3)
encrypted = encrypted.subarray(0, encrypted.size() - signed_len - 3)
if not StaticManager.crypto_verify_short(encrypted, signed):
return {}
if sign_version == 1:
decrypted = clAes.ECB_Decrypted(encrypted)
priorVersion = true
elif sign_version == 2:
encrypted = Global.hex_decode(encrypted.get_string_from_ascii())
decrypted = clAes.ECB_Decrypted(encrypted)
else :
return {}
可以看到是使用了 AES 的 ECB 加密。
数据段的最后一个字节是 sign_version。
数据段的倒数第二个字节是 signed_len。
数据段的真实数据长度是 size - 2 - signed_len。
数据段校验逻辑：
func crypto_verify_short(data:PoolByteArray, signature:PoolByteArray)->bool:
crypto_init()
var hashed = data.get_string_from_utf8().md5_buffer()
return crypto.verify(HashingContext.HASH_MD5, hashed, signature, signer)
md5 校验，还加了私钥签名，非常的合理
编写解密脚本
一通搜索与实验，作者使用的 godot 是 3.x 的版本，4.0 api有些变化，找到了一个online playground（我最讨厌加密的地方就是每个平台算法都可能不一致，所以最好找一样的环境进行算法逆向）:
https://gdscript-online.github.io/
解密脚本如下：
extends Node
func _ready():
var data = "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"
var d = decrypt_skill_data(data)
print(d)
func decrypt_skill_data(skills:String) -> String :
var encrypted = PoolByteArray(hex_decode(skills))
var sign_version = encrypted[encrypted.size() - 1]
var signed_len = encrypted[encrypted.size() - 2]
var signed = encrypted.subarray(encrypted.size() - signed_len - 2, encrypted.size() - 3)
encrypted = encrypted.subarray(0, encrypted.size() - signed_len - 3)
encrypted = hex_decode(encrypted.get_string_from_ascii())
var decrypted = ECB_Decrypted(encrypted)
return decrypted.get_string_from_ascii()
func ECB_Decrypted(encrypted:PoolByteArray)->PoolByteArray:
if encrypted.empty():
return PoolByteArray([])
var aes = AESContext.new()
var key = "gd secret key!!!"
aes.start(AESContext.MODE_ECB_DECRYPT, key.to_utf8())
var decrypted:PoolByteArray = aes.update(encrypted)
aes.finish()
return decrypted
func hex_decode(data:String)->PoolByteArray:
var ret = []
var b:int = 0
var odd = true
for c in data.to_lower():
if c in "abcdef":
b += ord(c) - ord("a") + 10
else :
b += int(c)
if odd:
b *= 16
odd = false
else :
ret.append(b)
odd = true
b = 0
return ret
神奇的事情出现了，发现 diy_skils 里面解出来的全部是同一个字符串：
{"LV1":"","LV2":"","LV3":"","LV4":"","LV5":"","LV6":"","LV7":"","LV8":""}
有点不对劲，打印hex数据出来看看，果然有区别，这个在线编辑器真辣鸡：
[123, 34, 76, 86, 49, 34, 58, 34, 229, 190, 183, 229, 138, 169, 34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34, 233, 149, 191, 229, 133, 181, 34, 44, 34, 76, 86, 52, 34, 58, 34, 34, 44, 34, 76, 86, 53, 34, 58, 34, 230, 153, 186, 232, 191, 159, 34, 44, 34, 76, 86, 54, 34, 58, 34, 34, 44, 34, 76, 86, 55, 34, 58, 34, 230, 188, 171, 229, 176, 132, 34, 44, 34, 76, 86, 56, 34, 58, 34, 34, 125, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[123, 34, 76, 86, 49, 34, 58, 34, 230, 128, 165, 230, 148, 187, 34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34, 229, 136, 154, 231, 155, 180, 34, 44, 34, 76, 86, 52, 34, 58, 34, 34, 44, 34, 76, 86, 53, 34, 58, 34, 229, 164, 135, 230, 136, 152, 34, 44, 34, 76, 86, 54, 34, 58, 34, 34, 44, 34, 76, 86, 55, 34, 58, 34, 231, 153, 189, 230, 175, 166, 34, 44, 34, 76, 86, 56, 34, 58, 34, 34, 125, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
{ " L V 1 " : " x x x x x x " ,
使用 java 打印数组：
{"LV1":"�攻","LV2":"","LV3":"刚直","LV4":"","LV5":"备战","LV6":"","LV7":"白毦","LV8":""}
可以看到上面标记 x 的地方应该就是技能的 id 之类的了，所以我们需要替换这个id，再加密后覆盖应该就可以。
找两个有同样技能的存档验证一下，解密出来比较一下数组，发现技能相同的数组值确实是一样的，这样就确定可以直接替换了。
先尝试搜索一下这些技能数组，看看源码里面有没有，尝试无果。只能自己手动刷技能，然后填进去了。
替换数据
首先，拿到存档里面的技能数据，然后拼接成字节数组：
[123, 34, 76, 86, 49, 34, 58, 34]
// 智迟
skill1 = [230, 153, 186, 232, 191, 159]
[34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34]
// 藤甲
skill2 = [232, 151, 164, 231, 148, 178]
[34, 44, 34, 76, 86, 52, 34, 58, 34, 34, 44, 34, 76, 86, 53, 34, 58, 34]
// 白毦
skill3 = [231, 153, 189, 230, 175, 166]
[34, 44, 34, 76, 86, 52, 34, 58, 34, 34, 44, 34, 76, 86, 53, 34, 58, 34]
// 玄阵
skill4 = [231, 142, 132, 233, 152, 181]
[34, 44, 34, 76, 86, 56, 34, 58, 34, 34, 125, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
编写加密逻辑：
func ECB_Encrypted(data:PoolByteArray)->PoolByteArray:
var aes = AESContext.new()
var key = "gd secret key!!!"
while data.size() % 16 != 0:
data.append(0)
aes.start(AESContext.MODE_ECB_ENCRYPT, key.to_utf8())
var encrypted:PoolByteArray = aes.update(data)
aes.finish()
return encrypted
编写签名逻辑：
func crypto_sign_short(data:PoolByteArray)->PoolByteArray:
var crypto = Crypto.new()
var signer = CryptoKey.new()
signer.load_from_string("""
-----BEGIN RSA PRIVATE KEY-----
MIIBOwIBAAJBAOTW56JN2BCV/G//PQn4/Kz06h92jmdbUIM+KmzQrbvNVwiobwEd
3VvEsmDa6pQ0JFgVY8dr66Hc18HLShwJEq8CAwEAAQJADMHUQO6RBH+wBnhWqUcp
ouS2ZpGf57AmAWMGT3GktcrmOR+W4vjS9B2iFH/JhJDBMkQ+5py9+fMCE5gc0gMS
RQIhAPZUCEJAAl6y1FggoiVpaSUT9g9TdBYJfr/6wOPfqXebAiEA7dMVioDfqQ5t
zH2KySLtEVe2ANWroJLwL8Ts3vUVxH0CIQC7hlWTOe+T8Eg/nvhRyuHE3GFiYYHq
lOftdxQJZmg5KQIgWg+fjq2zBSAzsEaycezJ/dFLWRGRRuOeFVjropsJPTkCIQDt
p9I6LkIJqfid8y4YC1mSFF0g4ClEoAIv918R47hAEA==
-----END RSA PRIVATE KEY-----
""", false)
var hashed = data.get_string_from_utf8().md5_buffer()
return crypto.sign(HashingContext.HASH_MD5, hashed, signer)
测试签名逻辑是否正确：
func test():
var skills_data = "6336336237386135643733383165303730626537356434643035633430373237363734393235333431626362646562323732656234313732316562613862613134333632323035333335646265613765303838336432303637643639623239363633356637653430313730346238616462643564623530383764326261383138333834363638376239393533346133386630316437363638633362623932616233626634623139663539613231316664366663356166306635303232393735326163633233336436363836653839636563326336626338393662306563333630"
skills_data = hex_decode(skills_data)
var sign_data = "ba172a595d70137e650f34567238b2c6112bf15a8f1a238d4c0f9502a5b4bc5366235529243de0cb3e5cd797b9d85f5b36b7be899cda27065b0a505b722e9ddc"
var my_sign_data = crypto_sign_short(skills_data)
print(my_sign_data.hex_encode())
运行是匹配的，完美。
最后，生成技能代码：
func generate_skills_data():
var result_data = PoolByteArray([])
var skills_data = get_skills();
skills_data = ECB_Encrypted(skills_data).hex_encode().to_ascii()
result_data.append_array(skills_data)
var sign_data = crypto_sign_short(skills_data)
result_data.append_array(sign_data)
result_data.append(64)
result_data.append(2)
print(result_data)
var hex_string = result_data.hex_encode()
print(hex_string)
替换存档数据，查看：
嗯？？？有bug，再重新读档一下，发现技能没变，说明签名逻辑没问题，数据也没问题。看来是技能id还有些东西没搞出来，需要再研究研究。
技能修正
突然想到游戏逻辑的一段代码，猜测技能代码里面的那6个字节数组其实是汉字：
var skillsData = JSON.print(skills).to_utf8()
测试一下，那个 godot 在线编辑器居然不能输出汉字，辣鸡。
使用 js 测试一下看看：
果然如此，那我们就可以重构代码了，在 4.x 版本的编辑器（https://gd.tumeo.space/#）里输出数组对比一下：
extends Node
func _ready():
# var data = "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"
# var d = decrypt_skill_data(data)
# print(d)
var skills = {
"LV1":"智迟",
"LV2":"",
"LV3":"藤甲",
"LV4":"",
"LV5":"白毦",
"LV6":"",
"LV7":"玄阵",
"LV8":""
};
var skillsData = JSON.stringify(skills).to_utf8_buffer()
print(PackedByteArray(skillsData))
与我们自己拼接的是一样的，看来我们的数据是没错。
补充
后来将技能调整了下顺序就可以了，有点奇怪，懒得调试了，查了下神武是默认值。使用字符串来生成数组的方式没有出过错了。上面代码可用。
完整代码
extends Node
func _ready():
# var data = "6336336237386135643733383165303730626537356434643035633430373237363734393235333431626362646562323732656234313732316562613862613134333632323035333335646265613765303838336432303637643639623239363633356637653430313730346238616462643564623530383764326261383138333834363638376239393533346133386630316437363638633362623932616233626634623139663539613231316664366663356166306635303232393735326163633233336436363836653839636563326336626338393662306563333630ba172a595d70137e650f34567238b2c6112bf15a8f1a238d4c0f9502a5b4bc5366235529243de0cb3e5cd797b9d85f5b36b7be899cda27065b0a505b722e9ddc4002"
# var d = decrypt_skill_data(data)
# print(d)
test()
generate_skills_data()
func test():
var skills_data = "6336336237386135643733383165303730626537356434643035633430373237363734393235333431626362646562323732656234313732316562613862613134333632323035333335646265613765303838336432303637643639623239363633356637653430313730346238616462643564623530383764326261383138333834363638376239393533346133386630316437363638633362623932616233626634623139663539613231316664366663356166306635303232393735326163633233336436363836653839636563326336626338393662306563333630"
skills_data = hex_decode(skills_data)
var sign_data = "ba172a595d70137e650f34567238b2c6112bf15a8f1a238d4c0f9502a5b4bc5366235529243de0cb3e5cd797b9d85f5b36b7be899cda27065b0a505b722e9ddc"
var my_sign_data = crypto_sign_short(skills_data)
print(my_sign_data.hex_encode())
func decrypt_skill_data(skills:String) -> String :
var encrypted = PoolByteArray(hex_decode(skills))
var sign_version = encrypted[encrypted.size() - 1]
var signed_len = encrypted[encrypted.size() - 2]
var signed = encrypted.subarray(encrypted.size() - signed_len - 2, encrypted.size() - 3)
encrypted = encrypted.subarray(0, encrypted.size() - signed_len - 3)
encrypted = hex_decode(encrypted.get_string_from_ascii())
var decrypted = ECB_Decrypted(encrypted)
print(decrypted)
return decrypted.get_string_from_ascii()
func ECB_Encrypted(data:PoolByteArray)->PoolByteArray:
var aes = AESContext.new()
var key = "gd secret key!!!"
while data.size() % 16 != 0:
data.append(0)
aes.start(AESContext.MODE_ECB_ENCRYPT, key.to_utf8())
var encrypted:PoolByteArray = aes.update(data)
aes.finish()
return encrypted
func ECB_Decrypted(encrypted:PoolByteArray)->PoolByteArray:
if encrypted.empty():
return PoolByteArray([])
var aes = AESContext.new()
var key = "gd secret key!!!"
aes.start(AESContext.MODE_ECB_DECRYPT, key.to_utf8())
var decrypted:PoolByteArray = aes.update(encrypted)
aes.finish()
return decrypted
func hex_decode(data:String)->PoolByteArray:
var ret = []
var b:int = 0
var odd = true
for c in data.to_lower():
if c in "abcdef":
b += ord(c) - ord("a") + 10
else :
b += int(c)
if odd:
b *= 16
odd = false
else :
ret.append(b)
odd = true
b = 0
return ret
func generate_skills_data():
var result_data = PoolByteArray([])
var skills_data = get_skills();
skills_data = ECB_Encrypted(skills_data).hex_encode().to_ascii()
result_data.append_array(skills_data)
var sign_data = crypto_sign_short(skills_data)
result_data.append_array(sign_data)
result_data.append(64)
result_data.append(2)
print(result_data)
var hex_string = result_data.hex_encode()
print(hex_string)
func get_skills()->PoolByteArray:
var skill1 = [230, 153, 186, 232, 191, 159]
var skill2 = [232, 151, 164, 231, 148, 178]
var skill3 = [231, 153, 189, 230, 175, 166]
var skill4 = [231, 142, 132, 233, 152, 181]
var skills = [123, 34, 76, 86, 49, 34, 58, 34]
skills.append_array(skill1)
skills.append_array([34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34])
skills.append_array(skill2)
skills.append_array([34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34])
skills.append_array(skill3)
skills.append_array([34, 44, 34, 76, 86, 50, 34, 58, 34, 34, 44, 34, 76, 86, 51, 34, 58, 34])
skills.append_array(skill4)
skills.append_array([34, 44, 34, 76, 86, 56, 34, 58, 34, 34, 125, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
return PoolByteArray(skills)
func crypto_sign_short(data:PoolByteArray)->PoolByteArray:
var crypto = Crypto.new()
var signer = CryptoKey.new()
signer.load_from_string("""
-----BEGIN RSA PRIVATE KEY-----
MIIBOwIBAAJBAOTW56JN2BCV/G//PQn4/Kz06h92jmdbUIM+KmzQrbvNVwiobwEd
3VvEsmDa6pQ0JFgVY8dr66Hc18HLShwJEq8CAwEAAQJADMHUQO6RBH+wBnhWqUcp
ouS2ZpGf57AmAWMGT3GktcrmOR+W4vjS9B2iFH/JhJDBMkQ+5py9+fMCE5gc0gMS
RQIhAPZUCEJAAl6y1FggoiVpaSUT9g9TdBYJfr/6wOPfqXebAiEA7dMVioDfqQ5t
zH2KySLtEVe2ANWroJLwL8Ts3vUVxH0CIQC7hlWTOe+T8Eg/nvhRyuHE3GFiYYHq
lOftdxQJZmg5KQIgWg+fjq2zBSAzsEaycezJ/dFLWRGRRuOeFVjropsJPTkCIQDt
p9I6LkIJqfid8y4YC1mSFF0g4ClEoAIv918R47hAEA==
-----END RSA PRIVATE KEY-----
""", false)
var hashed = data.get_string_from_utf8().md5_buffer()
return crypto.sign(HashingContext.HASH_MD5, hashed, signer)
Android 版技能修改器
后来，在Android 里面测试了一下算法，是通用的，所以就写了一个Android版的修改器，再也不用开网页修改了。
https://github.com/aprz512/sgz-gd-save-editor
