[Announce] Security fixes for Libgcrypt and GnuPG 1.4 [CVE-2016-6316]

Gerry Mander's Avatar

Gerry Mander

17 Aug, 2016 09:59 PM

[Announce] Security fixes for Libgcrypt and GnuPG 1.4 [CVE-2016-6316] Werner Koch wk at gnupg.org
Wed Aug 17 18:06:56 CEST 2016


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The GnuPG Project is pleased to announce the availability of new
Libgcrypt and GnuPG versions to fix a critical security problem.

Felix Dörre and Vladimir Klebanov from the Karlsruhe Institute of
Technology found a bug in the mixing functions of Libgcrypt's random
number generator: An attacker who obtains 4640 bits from the RNG can
trivially predict the next 160 bits of output. This bug exists since
1998 in all GnuPG and Libgcrypt versions.


All Libgcrypt and GnuPG versions released before 2016-08-17 are affected
on all platforms.

A first analysis on the impact of this bug in GnuPG shows that existing
RSA keys are not weakened. For DSA and Elgamal keys it is also unlikely
that the private key can be predicted from other public information.
This needs more research and I would suggest not to overhasty revoke


If you are using a vendor supplied version of GnuPG or Libgcrypt:

  • Wait for an update from your vendor.

If you are using a GnuPG-2 version (2.0.x or 2.1.x):

  • Update Libgcrypt. We have released these fixed versions of Libgcrypt: 1.7.3, 1.6.6, and 1.5.6. See below for download information.

If you are using GnuPG-1 version (1.4.x):

  • Update as soon as possible to GnuPG 1.4.21. See below for download information.


For help on developing with GnuPG or Libgcrypt you should read the
included manuals and ask on the appropriate mailing list [1,2]. A
listing with commercial support offers for GnuPG and Libgcrypt and
related software is available at the GnuPG web site [3].

Maintenance and development of GnuPG and Libgcrypt is mostly financed by
donations; see https://gnupg.org/donate/. We need your donations to
continue our work.


We like to thank all the people who helped with this release, be it
testing, coding, translating, suggesting, auditing, administering the
servers, spreading the word, and answering questions on the mailing
lists. Thanks to Felix Dörre and Vladimir Klebanov for sending us a
draft of their research paper and working with us on a solution. Also
many thanks to all our donors [4].


Source code is hosted at the GnuPG FTP server and its mirrors as listed
at https://gnupg.org/download/mirrors.html. On the primary server the
source tarballs and their digital signature are:

ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.7.3.tar.bz2 ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.7.3.tar.bz2.sig

ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.6.tar.bz2 ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.6.tar.bz2.sig

ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.5.6.tar.bz2 ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.5.6.tar.bz2.sig

ftp://ftp.gnupg.org/gcrypt/gnupg/gnupg-1.4.21.tar.bz2 ftp://ftp.gnupg.org/gcrypt/gnupg/gnupg-1.4.21.tar.bz2.sig

These files are also available via HTTP:

https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.3.tar.bz2 https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.3.tar.bz2.sig




Checking the Integrity

In order to check that the version you downloaded is an original
and unmodified file please follow the instructions found at
https://gnupg.org/download/integrity_check.html. In short, you may
use one of the following methods:

  • Check the supplied OpenPGP signature. For example to check the signature of the file libgcrypt-1.7.4.tar.bz2 you would use this command:

    gpg --verify libgcrypt-1.7.4.tar.bz2.sig libgcrypt-1.7.4.tar.bz2

    This checks whether the signature file matches the source file. You should see a message indicating that the signature is good and made by one or more of the release signing keys.

  • If you are not able to use GnuPG, you have to verify the SHA-1 checksum. For example:

    sha1sum libgcrypt-1.7.3.tar.bz2

    and check that the output matches the first line from the this list:

5a034291e7248592605db448481478e6c963aa9c libgcrypt-1.7.3.tar.bz2
a05cba7037e6cbc68dcf3ea5b45f703b79fa234f libgcrypt-1.7.3.tar.gz
ad79fd0b6963e1049612aa5d98e1a0b8eb775701 libgcrypt-1.6.6.tar.bz2
d11b6ca1d55eb12f5d3091a5169d874806007130 libgcrypt-1.6.6.tar.gz
62eade7cd3545efee1a87512d54f69151abbae47 libgcrypt-1.5.6.tar.bz2
8d3f55cce21e17f21d0c991cccf6bf52ec244353 libgcrypt-1.5.6.tar.gz
e3bdb585026f752ae91360f45c28e76e4a15d338 gnupg-1.4.21.tar.bz2
97bfba0e4db7cb1a3458f73240481767cb7fe90e gnupg-1.4.21.tar.gz

You should also verify that the checksums above are authentic by matching them with copies of this announcement. Those copies can be found at other mailing lists, web sites, and search engines.

Release Signing Keys

To guarantee that a downloaded GnuPG version has not been tampered by
malicious entities we provide signature files for all tarballs and
binary versions. The keys are also signed by the long term keys of
their respective owners. Current releases are signed by one or more
of these four keys:

2048R/4F25E3B6 2011-01-12 [expires: 2019-12-31] Key fingerprint = D869 2123 C406 5DEA 5E0F 3AB5 249B 39D2 4F25 E3B6 Werner Koch (dist sig)

rsa2048/E0856959 2014-10-29 [expires: 2019-12-31] Key fingerprint = 46CC 7308 65BB 5C78 EBAB ADCF 0437 6F3E E085 6959 David Shaw (GnuPG Release Signing Key)

rsa2048/33BD3F06 2014-10-29 [expires: 2016-10-28] Key fingerprint = 031E C253 6E58 0D8E A286 A9F2 2071 B08A 33BD 3F06 NIIBE Yutaka (GnuPG Release Key)

rsa2048/7EFD60D9 2014-10-19 [expires: 2020-12-31] Key fingerprint = D238 EA65 D64C 67ED 4C30 73F2 8A86 1B1C 7EFD 60D9 Werner Koch (Release Signing Key)

You may retrieve these keys from a keyserver using this command

gpg --keyserver hkp://keys.gnupg.net --recv-keys \ 249B39D24F25E3B6 04376F3EE0856959 \ 2071B08A33BD3F06 8A861B1C7EFD60D9

The keys are also available at https://gnupg.org/signature_key.html and
in any recently released GnuPG tarball in the file g10/distsigkey.gpg .
Note that this mail has been signed by a different key.

For the GnuPG hackers,


This is an announcement only mailing list. Please send replies only to
the gnupg-users 'at' gnupg.org mailing list.

[1] https://lists.gnupg.org/mailman/listinfo/gnupg-devel [2] https://lists.gnupg.org/mailman/listinfo/gcrypt-devel [3] https://www.gnupg.org/service.html [4] https://gnupg.org/donate/kudos.html

Die Gedanken sind frei. Ausnahmen regelt ein Bundesgesetz.
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  1. Support Staff 1 Posted by Steve on 18 Aug, 2016 11:38 AM

    Steve's Avatar

    Hey Gerry,

    welcome to the GPGTools community support platform.

    Thanks for the ping. We have a ticket for this problem. I connected this discussion with the existing ticket. That means, should this discussion get closed, it will be re-opened as soon as the ticket is closed. That way you'll stay in the loop and get notified as soon as we have news. Feel free to open a new discussions should you run into further problems or need assistance.

    All the best,

  2. Support Staff 2 Posted by Steve on 23 Aug, 2016 03:31 PM

    Steve's Avatar

    Hi Gerry,

    this issue has been fixed. If you want to test the fix, please download our latest nightly GPG Suite, 1696n or newer. That page also has sig and SHA1 to verify the download.

    Best, steve

    Disclaimer: This is a development version which has not been thoroughly tested yet, so bugs or crashes are to be expected. Thanks for helping us test this fix.

  3. Steve closed this discussion on 20 Apr, 2017 02:26 PM.

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