The blog of dlaa.me

While working on code for an upcoming blog post, I found myself dealing with the HashAlgorithm.HashSize property again and realized I'd made a silly mistake a few days ago... :(

I'm pretty sure I remember consulting the documentation when implementing this method for my free CRC-32 HashAlgorithm implementation, and I obviously believed the correct behavior was to return the size in bytes because that's what my comment says and that's what my code does. However, the documentation seems pretty clear on the matter: Gets the size, in bits, of the computed hash code." (emphasis mine). So my initial implementation of this property was wrong. Fortunately, none of the four implementations of ComputeFileHashes (command-line, WPF, ClickOnce, Silverlight) make use of HashSize, so they're not affected by this bug. Unfortunately, anyone who decided to use my CRC-32 implementation and referenced this property would see the wrong value. For their sake, I've just made the trivial fix to the code (multiplying the byte count by 8 to get bit count), updated the comment for that property, added a note about the update to the bottom of the original post, and republished it.

I'm very sorry for the error and any trouble this may have caused.

PS - The version of CRC32.cs in the ComputeFileHashes source code download has not been updated - but will be in a few days as part of an upcoming post.