Re: [boost] Boost.Uuid and header-only support

Subject: Re: [boost] Boost.Uuid and header-only support
From: Peter Dimov (lists_at_[hidden])
Date: 2017-11-04 15:40:02

Andrey Semashev wrote:

> The proposal to make Boost.Random header-only was rejected by Steven.
>
> https://github.com/boostorg/random/pull/29

This sounds like essential context that might have been worth mentioning. 
:-)

Steven is right that we're still dependent on Boost.System, this needs to be 
solved somehow.

To get back to Uuid. The whole seed_rng file needs to be retired. It's only 
an implementation detail of a primitive operation that returns N random 
bytes. At the time seed_rng was written, there was no good way of obtaining 
high quality randomness from the OS, but this is not the case today.

What the Uuid library needs, when generating a random UUID, is just an array 
of random bytes; there's no need to create a random number generator, then 
seed it. None at all. This is historical baggage.

And in my opinion, all the conceptification and templatization in James's PR 
is completely unnecessary and just adds complexity. What we need is this:

namespace boost
{
    int get_random_bytes( void * buffer, size_t size ); // returns errno
}

This happens to match the Linux function with the same name but this is 
coincidental.

The implementation of this function needs to

- read from /dev/urandom on POSIX
- use RtlGenRandom on Windows desktop
- use Bcrypt on Windows non-desktop

We have to decide where to put it though. Utility springs to mind as a first 
candidate.

Switching topics back to Boost.Random, I consider the use of the token to 
select a cryptographic provider a bad practice. Even the POSIX path should 
ignore the token. get_random_bytes is the way to go. But that's a separate 
story.