Re: [hash2] Review of Hash2

From: Vinnie Falco (vinnie.falco_at_[hidden])
Date: 2024-12-13 17:51:39

On Fri, Dec 13, 2024 at 8:55 AM Peter Dimov via Boost <boost_at_[hidden]>
wrote:

> injecting nondeterminism in their default constructors seems user-hostile
> ...
> One might in principle make the case that a default constructor shouldn't
> be included
>

It is quite natural and expected that one can adapt an existing
cryptographic hash algorithm to work with types that are Hash2-enabled. The
default constructor has to exist, and should not have any additional
behavior beyond what is prescribed by the actual hash algorithm. For
example, a default constructed SHA256 hash algorithm should have the state
prescribed in rfc6234 for when the algorithm is initialized and before any
message data has been provided. Seeding or deleting the default constructor
works against this.

Thanks