aeldidi / encoding

A library for encoding and decoding data in various binary formats.

aeldidi/encoding

aeldidi/encoding is a library for encoding and decoding binary data in various formats. It's written in C but doesn't make use of the C runtime except for assert, meaning it should be usable in any situation. It's also been tested to build using C++ compilers.

Status

The following operations are supported:

• encoding, decoding, and validating UTF-8
• encoding, decoding, and validating UTF-16
• encoding, decoding, and validating base16 (hex.c/hex.h), base32, and base64
• encoding and decoding binary data in big or little endian byte order

Documentation

Each interface is documented in its respective header file. For example, the documentation for base64_encode is in a comment above the function prototype in base64.h.

Using aeldidi/encoding

Go to the releases page and download the latest release, which contains self-contained .c and .h files which you can compile and use.

Note that binary.h only contains static functions, and you include it directly.

Security Model

The lengths of all arrays and strings are passed explicitly to avoid buffer overruns.

When developing the library I considered embedding correctness checks in each encoding and decoding function which would then stop the operation and zero out any partially encoded/decoded memory. As a result of this performance suffered significantly, making the library unnecessarily slower when processing trusted input. As such, I refactored the library in the following way:

1. All input is assumed to be trusted, and encoding/decoding routines are optimized taking this into account.
2. Functions are provided to test the validity of any untrusted input.

For example, any buffer which utf8_valid returns true for is safe to decode using the utf8_decode function. This keeps the library fast when operating on trusted input, while also causing untrusted input to fail early.

License

aeldidi/encoding is licensed under the 0BSD License, which allows you to do whatever you want without restriction. See the included LICENSE file more details.