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OpenVPN-NL v2.1.4-fox6 released
by Adriaan de Jong 14 Feb '12

14 Feb '12

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 A new version of OpenVPN-NL is available on the OpenVPN-NL site [1]. This version fixes a few small issues reported by the community, and includes support for the random number generator introduced in PolarSSL v1.1.0 [2]. Aside from these technical changes, the deployment advisory has been updated with a new section on virtual machines. Details of these changes will be given in the next few sections. Due to the improvements in the random number generator, we strongly recommend that you upgrade to the new version of OpenVPN-NL. New PolarSSL RNG - ---------------- In response to security concerns PolarSSL has introduced a new random number generator. It consists of two parts: an entropy gathering function, which allows the combination of a number of entropy sources, and a front-end deterministic random bit generator (DRBG), based on NIST-SP800-90 [3]. OpenVPN-NL uses a combination of the existing HAVEGE random number generator and the platform entropy device (e.g. /dev/random on Linux, CryptoAPI on Windows) as entropy sources. Two new OpenVPN-NL command line options have been introduced to allow users to tweak the new RNG: - min-platform-entropy: On Linux, sets the minimum number of bytes to read from /dev/random when reseeding. As /dev/random is blocking, setting this too high can cause OpenVPN-NL to block when not enough platform entropy is available. The deployment advisory recommends the use of at least 10 bytes. The default is 16 bytes. - use-prediction-resistance: Enables prediction resistance according to the NIST standard [3]. This should only be enabled if enough platform entropy is available. Enabling this option is recommended in the deployment advisory. The default is to disable prediction resistance. New deployment advisory - ----------------------- The deployment advisory has been updated to v1.2. This version adds a new paragraph on the use of OpenVPN-NL in virtual environments and on concentrators: "Users are advised to use hardware random number generators or entropy gathering daemons via the interfaces and conventions that the host offers. These feed into the system entropy pool. This is recommended on concentrators and systems that run in virtual environments. Enabling the use-prediction-resistance configuration option is recommended. Note that this may deplete kernel entropy sources more quickly. Users are advised not to adjust the configuration option min-platform-entropy below the value 10." Minor bug fixes - --------------- - Fixed bug in certificate serial number output to scripts. The last digit of the serial number was not output in some situations. - Disabled non-blocking connect on the Windows version, fixing the broken TCP behaviour. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQEcBAEBCAAGBQJPOiyPAAoJED0YDGtLy/yg4DwH/2SU8WKE1UuzFaMDquQPYGiJ 0HJXmnMXbpP4TTDTapmjObu0xcHpnG7r0tP9CcGA79LKjNEA35GMgThaWoeyHQDK 93+cCNYZHY+kKEWaMWKJ7O0sO0wsaQ8YpNTHMh07qqX5e7IwdpZBTYDW+hLVwi2z fmRQ9jszkHLgFjenOGIGIiHLBR+VQbljRx5iWMiIz4Dyd3YRsfoMObykWxdftQ8W w/TIQb4lW+mpOjLdSTwwrwBTNlwf7jK0CBTCEf0RvDER/9VXDzmcR5pvSsA1OzFe y/xxI/0ptvdtjaYlol3d682yPCar0UjKBidtWpqUR/zyq/dAujY6YDUI7ScNNlY= =qWLz -----END PGP SIGNATURE-----

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Deployment advisory update: use of OpenVPN-NL within virtualised environments
by Adriaan de Jong 01 Dec '11

01 Dec '11

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Feedback from the security community has triggered an investigation into the quality of PolarSSL's random number generation within virtualised environments. PolarSSL performs the random number generation and cryptographic functions required by OpenVPN-NL. To ensure that security is maintained while this investigation proceeds, the NLNCSA has added an extra restriction to its deployment advisory: - OpenVPN-NL should not be used in virtualised environments. This restriction might be lifted in the future, depending on the results of the investigation. We would like to thank Jacob Appelbaum, Marsh Ray, and Oscar Koeroo for starting the discussion on this matter. Details - ------- PolarSSL versions prior to v1.1 use only the HAVEGE random number generation algorithm. At its heart, this uses timing information based on the processor's high resolution timer (the RDTSC instruction). This instruction can be virtualised, and some virtual machine hosts have chosen to disable this instruction, returning 0s or predictable results. Currently, the problem appears to be limited to commercial cloud server providers. Solution - -------- A new version of PolarSSL, v1.1, will be released within a few days. This contains a new random number generator based on the CTR_DRBG algorithm specified in NIST SP-800-90. The entropy used by this algorithm is accumulated from multiple sources, including the existing Havege RNG, platform-specific entropy sources and timing sources. This increases the quality of the entropy pool, and makes it less vulnerable to problems within a single source. Once this new RNG has been succesfully evaluated, it will be included in future releases of OpenVPN-NL. Further research is also being done to determine the overall quality of random number generation within virtual machines. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQEcBAEBCAAGBQJO15v9AAoJED0YDGtLy/ygUnwIAIbFJ+tz/MKvv0VlSRq9ch53 J/4L57esdUKdjT7oy0E03dTU26LAteuMd/5YeEIGwegl9ImY0xvTReQhF4GZ7+oS O1zzsynH1B1bYY8l8ncIM19SW91T1MaKHpJsd5eVr8uKBPcsLAEKuXil0U7US11w mkMbdMIpzXU/b6SLMN1RrS3YU0kvkLBpDp0eOywl+QbHVf2ifiwXHw+6m7zHPXDC WsPnGLiEfDvVaWGvVfUC285zXuCQ+nnbrk2bCvFugAuKziSqt/x5W9LcmhICvKXg IQufGt9JEg3ADW7xn627RdMCDKy9emUo0peOWKYyTN56o3oMPVff9YsQaDlkr10= =mPMD -----END PGP SIGNATURE-----

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