✅ Can't figure out a way to make TransformFinalBlock work

here's my code

public class IncrementalHasher
{
    private readonly SHA1 _sha1 = SHA1.Create();

    public void AddBlock(byte[] buffer, int bytesRead)
    {
        int writtenBytes = _sha1.TransformBlock(buffer, 0, bytesRead, null, 0);
        Debugger.SendInfo(writtenBytes + " hashed");
    }

    public string FinalizeHash()
    {
        byte[] hashBytes = _sha1.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
        return Convert.ToHexStringLower(hashBytes);
    }
}

public class IncrementalHasher
{
    private readonly SHA1 _sha1 = SHA1.Create();

    public void AddBlock(byte[] buffer, int bytesRead)
    {
        int writtenBytes = _sha1.TransformBlock(buffer, 0, bytesRead, null, 0);
        Debugger.SendInfo(writtenBytes + " hashed");
    }

    public string FinalizeHash()
    {
        byte[] hashBytes = _sha1.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
        return Convert.ToHexStringLower(hashBytes);
    }
}

how I use it is for a download function that needs to hash the data that is beeing downloaded in small packets, dynamically as the download goes on. I believe that is exactly what TransformBlock and TransformFinalBlock are made for.
The little debug thing works for the 1st method, it does display valus that seem coherents.
But the 2nd method is the issue, TransformFinalBlock returns an empty array, and that sucks. I don't set any paramaters since all of that is done with TransformBlock, and I believe TransformFinalBlock returns the hash resulting from all the blocks given to TransformBlock. So what is the issue here and how can I fix it ?

Thx for any help in advance.

C#•7mo ago•

20 replies

armoire

✅ Can't figure out a way to make TransformFinalBlock work

here's my code

public class IncrementalHasher
{
    private readonly SHA1 _sha1 = SHA1.Create();

    public void AddBlock(byte[] buffer, int bytesRead)
    {
        int writtenBytes = _sha1.TransformBlock(buffer, 0, bytesRead, null, 0);
        Debugger.SendInfo(writtenBytes + " hashed");
    }

    public string FinalizeHash()
    {
        byte[] hashBytes = _sha1.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
        return Convert.ToHexStringLower(hashBytes);
    }
}

public class IncrementalHasher
{
    private readonly SHA1 _sha1 = SHA1.Create();

    public void AddBlock(byte[] buffer, int bytesRead)
    {
        int writtenBytes = _sha1.TransformBlock(buffer, 0, bytesRead, null, 0);
        Debugger.SendInfo(writtenBytes + " hashed");
    }

    public string FinalizeHash()
    {
        byte[] hashBytes = _sha1.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
        return Convert.ToHexStringLower(hashBytes);
    }
}

✅ Can't figure out a way to make TransformFinalBlock work

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