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

Am Thu, 18 Feb 2016 09:29:26 -0700
Ian Lepore <ian_at_freebsd.org> schrieb:

> 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

The "openssl passwd -1" refers to MD5 hashes, as I understand the manpage, but I require
at least sha256. With this solution suggested, I'd have the password still stored
in cleartext somewhere - if not read -in via read or similar.

If you snip off the openssl portion and substitute "-H0" with "-h0", then this is the way
I did before - as defined/configured in login.conf (usually in
${IMAGE_CHROOT_DIR}/etc) SHA512 will be used as digest algorithm and the password seems
"salted", prepended by the $6$ characters.

I'd like to have something like

echo ${password} | openssl passwd -sha512 -stdin -salt VerySalty

and store the result in a variable somewhere for use with

echo ${password_salted_sha512_hash} | pw -V ${IMAGE_CHROOT_DIR}/etc usermod -n\
${username} -H 0

Thanks,

oh