return number of repaired errors

[ghost]

Hi,

Would it be possible to not only return the data but also the number of repaired errors?
That way, for example a communication-channel can switch to a lower bitrate if errors are detected.

[lrq3000]

Hello,

Normally you can know the number of errors by looking at the syndrome. I am not sure/can't remember if it is returned in the high level class, but if you manipulate the low-level functions manually (from the class it should be possible, just call the internal methods), and simply call the syndrome function, simply count the number of non-zero items and you'll have the number of errors/erasures corrected.

However, keep in mind that if the number of errors or erasures exceed the theoretical singleton bound, the syndrome can't be trusted and you can't know whether the decoder validly corrected the messages or not. That's an intrinsic limitation of all error correction codes. A workaround is to add a checksum in your message as an additional protection mechanism, that also is not guaranteed to always work (ie, risk of tampering by noise or attacker and then collision) but it significantly reduces the risks (ie, collision is highly unlikely if the tampering is caused by noise, but if there is an attacker scenario the likelihood is potentially higher).