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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Gentoo Linux Security Advisory GLSA 201612-01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - https://security.gentoo.org/ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Severity: Normal Title: GnuPG: RNG output is predictable Date: December 02, 2016 Bugs: #591536 ID: 201612-01
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Synopsis ========
Due to a design flaw, the output of GnuPG's Random Number Generator (RNG) is predictable.
Background ==========
The GNU Privacy Guard, GnuPG, is a free replacement for the PGP suite of cryptographic software.
Affected packages =================
------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 app-crypt/gnupg < 1.4.21 >= 1.4.21
Description ===========
A long standing bug (since 1998) in Libgcrypt (see "GLSA 201610-04" below) and GnuPG allows an attacker to predict the output from the standard RNG. Please review the "Entropy Loss and Output Predictability in the Libgcrypt PRNG" paper below for a deep technical analysis.
Impact ======
An attacker who obtains 580 bytes of the random number from the standard RNG can trivially predict the next 20 bytes of output.
This flaw does not affect the default generation of keys, because running gpg for key creation creates at most 2 keys from the pool. For a single 4096 bit RSA key, 512 bytes of random are required and thus for the second key (encryption subkey), 20 bytes could be predicted from the the first key.
However, the security of an OpenPGP key depends on the primary key (which was generated first) and thus the 20 predictable bytes should not be a problem. For the default key length of 2048 bit nothing will be predictable.
Workaround ==========
There is no known workaround at this time.
Resolution ==========
All GnuPG 1 users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=app-crypt/gnupg-1.4.21"
References ==========
[ 1 ] CVE-2016-6313 http://nvd.nist.gov/nvd.cfm?cvename=CVE-2016-6313 [ 2 ] Entropy Loss and Output Predictability in the Libgcrypt PRNG http://formal.iti.kit.edu/~klebanov/pubs/libgcrypt-cve-2016-6313.pdf [ 3 ] GLSA 201610-04 http://security.gentoo.org/glsa/201610-04
Availability ============
This GLSA and any updates to it are available for viewing at the Gentoo Security Website:
https://security.gentoo.org/glsa/201612-01
Concerns? =========
Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users' machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.
License =======
Copyright 2016 Gentoo Foundation, Inc; referenced text belongs to its owner(s).
The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.
http://creativecommons.org/licenses/by-sa/2.5
--------------22695FC59F4E082732B6D7E1 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
<html> <head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dutf= -8"> </head> <body bgcolor=3D"#FFFFFF" text=3D"#000000"> <p> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Du= tf-8"> </p> <pre style=3D"color: rgb(0, 0, 0); font-style: normal; font-variant-l= igatures: normal; font-variant-caps: normal; font-weight: normal; letter-= spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-tr= ansform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0= px; word-wrap: break-word; white-space: pre-wrap;">- - - - - - - - - - - = - - - - - - - - - - - - - - - - - - - - - - - - - Gentoo Linux Security Advisory GLSA 201612-01 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - <a class=3D"moz-txt-link-freet= ext" href=3D"https://security.gentoo.org/">https://security.gentoo.org/</= a> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Severity: Normal Title: GnuPG: RNG output is predictable Date: December 02, 2016 Bugs: #591536 ID: 201612-01
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Synopsis =3D=3D=3D=3D=3D=3D=3D=3D
Due to a design flaw, the output of GnuPG's Random Number Generator (RNG) is predictable.
Background =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
The GNU Privacy Guard, GnuPG, is a free replacement for the PGP suite of cryptographic software.
Affected packages =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 app-crypt/gnupg < 1.4.21 >=3D 1.= 4.21=20
Description =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
A long standing bug (since 1998) in Libgcrypt (see "GLSA 201610-04" below) and GnuPG allows an attacker to predict the output from the standard RNG. Please review the "Entropy Loss and Output Predictability in the Libgcrypt PRNG" paper below for a deep technical analysis.
Impact =3D=3D=3D=3D=3D=3D
An attacker who obtains 580 bytes of the random number from the standard RNG can trivially predict the next 20 bytes of output.
This flaw does not affect the default generation of keys, because running gpg for key creation creates at most 2 keys from the pool. For a single 4096 bit RSA key, 512 bytes of random are required and thus for the second key (encryption subkey), 20 bytes could be predicted from the the first key.
However, the security of an OpenPGP key depends on the primary key (which was generated first) and thus the 20 predictable bytes should not be a problem. For the default key length of 2048 bit nothing will be predictable.
Workaround =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
There is no known workaround at this time.
Resolution =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
All GnuPG 1 users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=3Dapp-crypt/gnupg-1.4.21"
References =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
[ 1 ] CVE-2016-6313 <a class=3D"moz-txt-link-freetext" href=3D"http://nvd.nist.gov/nvd.= cfm?cvename=3DCVE-2016-6313">http://nvd.nist.gov/nvd.cfm?cvename=3DCVE-20= 16-6313</a> [ 2 ] Entropy Loss and Output Predictability in the Libgcrypt PRNG <a class=3D"moz-txt-link-freetext" href=3D"http://formal.iti.kit.ed= u/~klebanov/pubs/libgcrypt-cve-2016-6313.pdf">http://formal.iti.kit.edu/~= klebanov/pubs/libgcrypt-cve-2016-6313.pdf</a> [ 3 ] GLSA 201610-04 <a class=3D"moz-txt-link-freetext" href=3D"http://security.gentoo.o= rg/glsa/201610-04">http://security.gentoo.org/glsa/201610-04</a>
Availability =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
This GLSA and any updates to it are available for viewing at the Gentoo Security Website:
<a class=3D"moz-txt-link-freetext" href=3D"https://security.gentoo.org/g= lsa/201612-01">https://security.gentoo.org/glsa/201612-01</a>
Concerns? =3D=3D=3D=3D=3D=3D=3D=3D=3D
Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users' machines is of utmost importance to us. Any security concerns should be addressed to <a class=3D"moz-txt-link-abbreviated" href=3D"mailto:security@gentoo.org"= >security@gentoo.org</a> or alternatively, you may file a bug at <a class=3D"moz-txt-link-freetext" href=3D"https://bugs.gentoo.org">https= ://bugs.gentoo.org</a>.
License =3D=3D=3D=3D=3D=3D=3D
Copyright 2016 Gentoo Foundation, Inc; referenced text belongs to its owner(s).
The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.
<a class=3D"moz-txt-link-freetext" href=3D"http://creativecommons.org/lic= enses/by-sa/2.5">http://creativecommons.org/licenses/by-sa/2.5</a></pre> </body> </html>
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