Binaries are not always strings
The door access project moves a lot a binaries data about. A short while ago after the project had been in the wild for 16 months an odd error appeared.
Cards that should have been valid were being rejected.
After an investigation I tracked it down to a
Data from the locks need to be reversed before doing any access checking. All worked fine until one day card data like the following turned up:
<<221, 152, 120, 6>>
Now string reverse on this does what it should and returns
<<6, 120, 221, 152>>
You can see that the first two bytes are copied and not reversed. Welcome to the world of UTF chars.
If you have binary data don’t treat it like a string, even though strings are binaries!