[rust-dev] Ephemeral byte arrays for cryptographic keys/plaintexts

Lee Braiden leebraid at gmail.com
Fri Jan 10 12:50:16 PST 2014

On 10/01/14 19:29, Tony Arcieri wrote:
> There's a particular type I'd love to see in core Rust: a bytebuffer 
> for crypto purposes which automatically provides what I'd call "good 
> crypto hygiene". It'd do the following things:
> - Avoid being paged out to swap by use of mlock/VirtualLock

This is a general memory setting, which is required for all sorts of 
use-cases: disk io buffers, device driver buffers, off-screen rendering, 
caching, important interactive elements (mouse pointers and application 
menus, for instance), which would hamper the user experience if they 
were paged in/out,  etc.  I'd go as far as to say that any system with 
swapping needs an easy way to lock memory like this.  It's not even 
really a crypto problem, since swap can (and probably should be) 
encrypted too, if you encrypt your filesystem(s).

I would like to see a platform-independent implementation in std::mem -- 
std::mem::lock(buf, len) and it's unlock() opposite, perhaps.

> - Ensure it's zeroed out (and munlocked) after use (via RAII-style 
> conventions?)

Isn't this just a dtor thing?

> - Be able to interact directly with the I/O layer so it's easy to get 
> data in/out of these buffers without having to thunk it through a 
> bunch of intermediate types that won't have these properties, i.e. it 
> should be possible for me to read an encryption key from a file 
> without going through a [u8] that wouldn't get locked/zeroed 
> automatically.

This sounds like a general IO optimisation, which virtually any 
block-based io use-case could benefit from.


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