关于nginx：使用OpenResty的resty.aes模块，Java Cipher.getInstance(” AES / CBC / NoPadding”)的解密结果失败

Decrypt result of Java Cipher.getInstance(“AES/CBC/NoPadding”) failed with OpenResty's resty.aes module

我正在开发nginx(openresty)Lua模块，其中一项要求是解密由旧版Java程序生成的加密字符串。但是我的Lua代码无法解密它，因此我在这里寻求帮助。

可以的Java加密和解密代码：

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public class AesCbc {
private static String PLAIN ="usr/passwd@bizdb:127.0.0.1:5432";

public static void main(String[] args) throws Exception {
Cipher aesCipher = Cipher.getInstance("AES/CBC/NoPadding");
SecretKeySpec keySpec = new SecretKeySpec("1234567890ABCDEF".getBytes(),"AES");
IvParameterSpec iv = new IvParameterSpec("fedcba0987654321".getBytes());

aesCipher.init(Cipher.ENCRYPT_MODE, keySpec, iv);
byte[] rawBytes = PLAIN.getBytes();
byte[] aligned;
int mod = rawBytes.length % 16; // prevent javax.crypto.IllegalBlockSizeException
if (mod == 0) {
aligned = new byte[rawBytes.length];
} else {
aligned = new byte[rawBytes.length + 16 - mod];
}
System.arraycopy(rawBytes, 0, aligned, 0, rawBytes.length);
byte[] cipherBytes = aesCipher.doFinal(aligned);
String base64Result = Base64.getEncoder().encodeToString(cipherBytes);
System.out.println("cipher:[" + base64Result +"], rawBytes.length=" + rawBytes.length +", mod=" + mod);

aesCipher.init(Cipher.DECRYPT_MODE, keySpec, iv);
cipherBytes = Base64.getDecoder().decode(base64Result);
aligned = aesCipher.doFinal(cipherBytes);
int posNil;
for (posNil = 0; posNil < aligned.length; posNil++) {
if (aligned[posNil] == 0x00)
break;
}
rawBytes = new byte[posNil];
System.arraycopy(aligned, 0, rawBytes, 0, posNil);
String plain = new String(rawBytes);
System.out.println("plain:[" + plain +"], posNil=" + posNil +", aligned.length=" + aligned.length);
}
}

Java代码的输出：

1 2	cipher:[l1buytGEL4RKa/RezInQ3dJxvMtL6nyE2wTi7VyoS4w=], rawBytes.length=31, mod=15 plain:[usr/passwd@bizdb:127.0.0.1:5432], posNil=31, aligned.length=32

我的Lua测试文件在nginx.conf-> http-> server部分中声明：

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location /aescbc {
content_by_lua_file conf/aescbc.lua;
}

conf / aescbc.lua的内容：

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-- aescbc.lua

local aes = require"resty.aes"
local str = require"resty.string"
local aes128Cbc = aes:new("1234567890ABCDEF", nil, aes.cipher(128,"cbc"), {iv="fedcba0987654321"})

-- result of AesCbc.java for my test
local BASE64CIPHER ="l1buytGEL4RKa/RezInQ3dJxvMtL6nyE2wTi7VyoS4w="

local cipherBytes = ngx.decode_base64(BASE64CIPHER)
if not cipherBytes then
ngx.log(ngx.WARN,"decode base64 [" .. BASE64CIPHER .."] failed")
return
end

local aligned = aes128Cbc:decrypt(cipherBytes)
if not aligned then
ngx.log(ngx.WARN,"decrypt cipherBytes [" .. str.to_hex(cipherBytes) .."] failed")
return
end

ngx.log(ngx.NOTICE,"aligned [" .. str.to_hex(aligned) .."]")
return

使用" curl http://127.0.0.1:8080/aescbc"进行测试时，nginx错误日志：

1	2017/08/03 11:28:26 [warn] 13799#0: *5 [lua] aescbc.lua:18: decrypt cipherBytes [9756eecad1842f844a6bf45ecc89d0ddd271bccb4bea7c84db04e2ed5ca84b8c] failed, client: 127.0.0.1, server: , request:"GET /aescbc HTTP/1.1", host:"127.0.0.1:8080"

我认为我使用resty.aes一定有问题，但是如何解决？

在网上搜索，阅读手册页并进行了几天的实验后，问题得以解决。所以我自己回答：

resty.aes模块使用OpenSSL的默认PKCS7填充算法，并且在当前版本的resty.aes中没有设置NoPadding选项的方法。所以我对此做了一个补丁：(添加填充参数并在aes：new中调用EVP_CIPHER_CTX_set_padding())

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$ diff ./lualib/resty/aes.lua.orig ./lualib/resty/aes.lua
79a80
> int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
128c129
< function _M.new(self, key, salt, _cipher, _hash, hash_rounds)
---
> function _M.new(self, key, salt, _cipher, _hash, hash_rounds, padding)
177a179,184
> end
>
> if padding then
> -- 0:NoPadding, 1:PKCS7(default), 2:ISO7816_4, 3:ANSI923, 4:ISO10126, 5:ZERO
> C.EVP_CIPHER_CTX_set_padding(encrypt_ctx, padding);
> C.EVP_CIPHER_CTX_set_padding(decrypt_ctx, padding);

并对lua测试代码做了一些小的修改：

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$ cat ./nginx/conf/aescbc.lua
-- aescbc.lua

local aes = require"resty.aes"
local str = require"resty.string"
local aes128Cbc = aes:new("1234567890ABCDEF", nil, aes.cipher(128,"cbc"), {iv="fedcba0987654321"}, nil, 0)

-- result of AesCbc.java for my test
local BASE64CIPHER ="l1buytGEL4RKa/RezInQ3dJxvMtL6nyE2wTi7VyoS4w="

local cipherBytes = ngx.decode_base64(BASE64CIPHER)
if not cipherBytes then
ngx.log(ngx.WARN,"decode base64 [" .. BASE64CIPHER .."] failed")
return
end

local aligned = aes128Cbc:decrypt(cipherBytes)
if not aligned then
ngx.log(ngx.WARN,"decrypt cipherBytes [" .. str.to_hex(cipherBytes) .."] failed")
return
end

ngx.log(ngx.NOTICE,"aligned [" .. str.to_hex(aligned) .."], len=" .. aligned:len())

local plain
local idx = aligned:find('\\0')
if idx then
plain = aligned:sub(1, idx - 1)
else
plain = aligned
end

ngx.log(ngx.NOTICE,"plain [" .. plain .."], len=" .. plain:len())

return

测试的nginx错误日志：

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2017/08/07 15:17:55 [notice] 34632#0: *21 [lua] aescbc.lua:22: aligned [7573722f7061737377644062697a64623a3132372e302e302e313a3534333200], len=32, client: 127.0.0.1, server: , request:"GET /aescbc HTTP/1.1", host:"127.0.0.1:8080"
2017/08/07 15:17:55 [notice] 34632#0: *21 [lua] aescbc.lua:32: plain [usr/passwd@bizdb:127.0.0.1:5432], len=31, client: 127.0.0.1, server: , request:"GET /aescbc HTTP/1.1", host:"127.0.0.1:8080"