BlockRng64 doesn't implement CryptoRng

[Pr0methean]

Problem: Although rand has the declaration

impl<R: BlockRngCore + CryptoRng> CryptoRng for BlockRng<R> {}

there's no equivalent for BlockRng64<R>, so a BlockRng64 can't pass any compile-time check for a CryptoRng even when the core does.

[dhardy]

This was already changed in master: #1273

And, yes, that's not released yet; there's a tracking issue for version 0.9 if you're interested.

[conradludgate]

Any reason why

impl<R: BlockRngCore + CryptoRng> CryptoRng for BlockRng64<R> {}

cannot be backported to rand_core 0.6.X?

What's the ETA on rand 0.9 (I couldn't find a tracking issue)?

[dhardy]

It may be possible to backport, but we haven't usually bothered. If you need a backport, open a PR against the 0.8 branch (or a new issue if you can't find the appropriate branch).

Rand v0.9 should be released tomorrow. You can use the latest beta release for now.