Re: [PATCH 5/5] Add arc4random() etc. from OpenBSD 5.8

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

On 18/03/16 14:50, Corinna Vinschen wrote:
> On Mar 18 12:28, Corinna Vinschen wrote:
> > >On Mar 18 11:49, Sebastian Huber wrote:
> > > > >According to the OpenBSD man page, "A Replacement Call for Random".  It
> > > > >offers high quality random numbers derived from input data obtained by
> > > > >the OpenBSD specific getentropy() system call which is declared in
> > > > ><unistd.h> and must be implemented for each Newlib port externally.  The
> > > > >arc4random() functions are used for example in LibreSSL and OpenSSH.
> > > > >
> > > > >Cygwin provides currently its own implementation of the arc4random
> > > > >family.  Maybe it makes sense to use this getentropy() implementation:
> > > > >
> > > > >http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libcrypto/crypto/getentropy_win.c?rev=1.4&content-type=text/x-cvsweb-markup
> > >
> > >No, that pulls in a dependency to another DLL which we're trying to avoid.
> > >Using RtlGenRandom should work though.  I have to test this.
> All patches applied.  I immediately implemented the changes required for
> Cygwin.  In the first place that required to add two functions
> arc4random_stir and arc4random_addrandom to maintain backward
> compatibility since both OpenBSD functions were already exported by
> Cygwin.

My aim with the "newlib/libc/sys/*/include/machine/_arc4random.h" file 
was to avoid #ifdef SYS_XYZ cascades in the generic files. It seems that 
for Cygwin there is no "newlib/libc/sys/cygwin" directory. Would it be 
possible to add this and place a 
"newlib/libc/sys/cygwin/include/machine/_arc4random.h" in it?

I am not sure if we should add the arc4random_stir() and 
arc4random_addrandom() functions, since this may lead configure scripts 
to enable their use. With the getentropy() system call I am not sure if 
this is harmful.

--
Sebastian Huber, embedded brains GmbH

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