[CentOS] Asymmetric encryption for very large tar file [NOW: Uselsss Use of CAT award!!]

[Fred Smith]

On Wed, Dec 17, 2014 at 06:58:40PM +0100, Markus wrote:
> On 17/12/14 18:54, Leon Fauster wrote:
> > Am 17.12.2014 um 18:42 schrieb Les Mikesell <lesmikesell at gmail.com>:
> >> On Wed, Dec 17, 2014 at 11:14 AM, Xinhuan Zheng
> >> <xzheng at christianbook.com> wrote:
> >>> I have a requirement that I need to use encryption technology to encrypt
> >>> very large tar file on a daily basis. The tar file is over 250G size and
> >>> those are data backup. Every night the server generated a 250G data backup
> >>> and it¹s tar¹ed into one tarball file. I want to encrypt this big tarball
> >>> file. So far I have tried two technologies with no success.
> >>> 1) generating RSA 2048 public/private key pair via ³openssl req -x509
> >>> -nodes -newkey rsa:2048 -keyout private.pem -out public.pem² command and
> >>> uses the public key to encrypt the big tar file. The encryption command I
> >>> used is "openssl smime -encrypt -aes256 -in  backup.tar -binary -outform
> >>> DEM -out backup.tar.ssl  public.pem². The resulting backup.tar.ssl file is
> >>> only 2G then encryption process stops there and refuse to do more. Cannot
> >>> get around 2G.
> >>
> >> What happens if you use a pipeline or redirection instead of the -in
> >> and -out files?   I regularly write large tapes with something like:
> >> openssl aes-256-cbc -salt -k password <input.tar.gz  |dd bs=10240
> >> obs=10240 of=/dev/nst0
> >> Not quite the same, but there does not seem to be an inherent size
> >> limit in openssl as long as it is not handling files and it happens at
> >> a reasonable speed so it must be using the intel hardware support.
> > 
> > 
> > 
> > Furthermore - is there the need to use "one" big tar file? Despite 
> > having a capable workstation/server handling such big files, it has 
> > also advantages splitting such backups (e.g. man split) ...
> > LF
<snip>
> 
> Is it possible for you to use gpg? You could do something like:
> tar zcf /something - | gpg -e -r otherkey | cat - > backup.tgz
> 
> Regards

or better yet:
tar zcf /something - | gpg -e -r otherkey > backup.tgz

If gpg can write to stdout, then it can write to a redirected stdout.
no need to use a superfluous cat in there.

and (without checking the man page) I'm not sure about the 'f' in the
tar commandline... I thought the 'f' referred to the output file???

-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us ----------------------------
                    Do you not know? Have you not heard? 
    The LORD is the everlasting God, the Creator of the ends of the earth. 
  He will not grow tired or weary, and his understanding no one can fathom.
----------------------------- Isaiah 40:28 (niv) -----------------------------