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This article mainly explains "how to expand encryption algorithm support for skynet's crypt library", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "how to expand encryption algorithm support for skynet's crypt library"!

Cause of transformation

In the last article, I described the beginning of adding stable websocket support to skynet and explained why.

During testing these days, I found that when using skynet's built-in httpc library, crypt lacked some algorithms I needed (for example, crc, sha256, hmac_sha256, etc.).

It is entirely possible to assume that developers do not find this problem in framework selection, which may not be found until the middle of development when third-party platforms need to connect to or extend different architectures.

Obviously, this will intangibly introduce unpredictable stability factors into a project. In order to avoid this factor as much as possible, it is necessary to extend some common encryption (summary) algorithm support.

The preferred solution must use a mature library. Unfortunately, lua5.3 does not have a more reliable and ready-made implementation library that can be used directly after fork.

And the only libraries that can be used for reference are the libraries implemented by luajit using ffi and the implementation of OpenSSL. However, these cannot be directly or indirectly transplanted to lua 5.3. 3.

This is the worst situation we have ever encountered. Finally, we can only use C API of Lua to glue the Crypt implementation of C language to complete the transformation of Crypt extension library of Lua version.

Transformation begins

I found a good Lua sha implementation after searching for a period of time on the Internet.

This code contains the C implementation of md5, sha128, sha384 and sha512, which uses a large number of macros to complete Lua injection actions. So the first thing we need to do is to get rid of these difficult-to-read macro definitions.

We know that a sha1 implementation already exists in skynet's luaclib-src/lsha1.c file. Then we can keep the sha1 and extract only the sha256 and sha512 implementation of the sha2 part.

The maintainability of sha2 has been greatly improved after it has been transformed into a standard Lua Model implementation, and it is obviously better to name it lsha2.c and lsha2.h. At this point, we can already use these algorithms for testing.

We all know that HMAC is a hash algorithm. At present, the hmac_256 and hmac_512 implementation of this hash algorithm has been widely used in many cloud platforms. A more obvious example is Tencent Cloud.

There is already a HMAC implementation code in the lsha1.c file, and we copy the xor_str algorithm to the lsha2 file. You can simply complete the expansion.

What you need to know here is that both sha128 and sha256 Block can use 64, but the block length of hmac_sha512 is 128. 5%. So we wrote a separate internal code for it to facilitate maintenance.

It is very easy to extend hmac_256 and hmac_512 with reference to lsha1.c 's hmac_sha128 implementation. Basically, it is written by block and Lua Model. It will be finished soon.

Md5. Skynet is already supported under the 3rd directory of md5. Although I don't know how to use it, I feel very inconvenient to use it. And hmac64_md5 supported by crypt library is currently inconvenient to interface with other languages.

Finally, we simply create the lmd5.c file mentioned above to implement a md5 algorithm, and then refer to the above hmac algorithm to implement a hmac_md5. This allows all algorithms to coexist within the crypt library.

When you see this! You must think that our work is done! However, this is not enough, now that we have started to do it. Then some common algorithms must be included.

Finally, we try to get the source code of crc32 and crc64 from the source file of redis, then directly extract it and transform it into a separate lcrc.c file and inject Lua C API into it.

Above, the basic transformation of crypt has been completed.

Transformation result

At present, the test results are consistent in other language sets. Because the implementation uses the C language, the performance is naturally better than some lua implementations. So you don't have to think too much about performance.

Now that you have an open source Websocket implementation, you might as well open source this code as well. As for naming, it continues the previous naming: skynet-lua-crypt.

Installation method

Since the modification involves the modification of files in the luaclib-src of skynet, the compilation method can not be compiled in the ordinary 3rd mode.

And some skynet files also use this library internally, we need to directly modify the skynet Makefile file to complete this replacement action. This can ensure that the fruit weaving is more smooth.

In order to follow up the version. I pulled the 1.2 version of skynet code for testing, after my MacBook Pro compilation and skynet/test/testsha.lua file test passed and no side effects.

Thank you for your reading, the above is the content of "how to extend encryption algorithm support for skynet's crypt library". After the study of this article, I believe you have a deeper understanding of how to expand encryption algorithm support for skynet's crypt library. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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