Re: HELP: Howtwo create a passwd-suitable hash for usage with psswd -H 0?

On Thu, 2016-02-18 at 16:29 +0100, O. Hartmann wrote:
> On Thu, 18 Feb 2016 14:52:44 +0000
> RW <rwmaillists_at_googlemail.com> wrote:
> 
> > On Thu, 18 Feb 2016 14:16:24 +0100
> > O. Hartmann wrote:
> > 
> > > Hello out there,
> > > 
> > > I run into a problem and digging for a solution didn't work out.
> > > 
> > > Problem: I need a string that reflects the hashed password for the
> > > usage with 
> > > 
> > > passwd -H 0  
> > 
> > Did you mean -h?
> 
> no, I literally mean -H 0, I explain later ...
> 
> > 
> > > I think the procedure is using 
> > > 
> > > sha512 -s Password
> > > 
> > > and using this output for further processing, but how?  
> > 
> > It's not as simple as that, password  hashes are usually salted and
> > iterated. Salting means that the password is combined with a randomly
> > generated string stored in plaintext, which means that the password
> > doesn't hash to a fixed string.
> > 
> > I'm not sure exactly what you are trying to do, but crypt(3) may be of
> > help.
> 
> I'm now down to a small C routine utilizing crypt(3). But this is not what I
> intend to have, since I want to use tools from the FBSD base system.
> 
> I build images of a small appliance in a secure isolated environment via
> NanoBSD. I do not want to have passwords in the clear around here, but I also
> do not want to type in everytime an image is created, so the idea is to have
> passwords prepared as hashes in a local file/in variables. Therefore, I'm
> inclined to use the option "-H 0" of the pw(1) command to provide an already
> and clean hash (SHA512), which is then stored in /etc/master.passwd.
> 
> It is really funny: passwd or pw take passwords via stdin (-h 0 with pw) and
> they "generate" somehow the hashed password and store that in master.password
> - but I didn't find any way to pipe out the writing of the password to the
> standard output from that piece of software. Why? Security concerns I forgot to
> consider?
> 
> I found lots of articles and howtos to use pipes producing the required
> password hashes via passwd, chpasswd or pw, but they all have one problem: I
> have to provide somehow the cleartext password in an automated environment.
> 
> Maybe there is something missing ...
> 
> oh

We use something like this at work (which I don't fully understand, but
it works on freebsd 6.x through 10.x at least)...

 echo ${password} | openssl passwd -1 -stdin -salt VerySalty | \
   pw -V ${IMAGE_CHROOT_DIR}/etc useradd -n ${username} -H0 $*

I guess for your use you'd capture and save the output of openssl so
you could later feed it back to pw when making images.

-- Ian