Month: February 2013

Here`s another good article on the Lucky Thirteen breach quoting SSL researcher Ivan Ristic:  http://www.computerworlduk.com/news/security/3424689/new-attack-techniques-against-ssl-revealed/

Researchers have found a new a new attack vector for TLS 1.1 and 1.2 protocol implementations, which wolfSSL has promptly fixed in its leading embedded TLS product.

In the paper “Lucky Thirteen: Breaking the TLS and DTLS Record Protocols” authors Nadhem AlFardan and Kenneth Paterson present a family of attacks that apply to CBC-mode for TLS (1.1 and 1.2) and DTLS (1.0 and 1.2). All of the attacks are based on a delicate timing analysis of the decryption processing needed in block mode. The various attacks are distinguishing, partial plaintext recovery, and full plaintext recovery in nature. All the attacks exploit the protocol when badly formatted padding is handled during processing. A MAC verification must still be performed on something to prevent existing timing attacks. The RFCs suggest using a zero-length pad which was thought to be safe, but these attacks show that it can be exploited.

There are a few ways to avoid the attack. Using stream ciphers is the simplest. Stream ciphers like ARC4, HC- 128, and RABBIT are not vulnerable because they don`t use block mode and padding. HC-128 and RABBIT are unique to wolfSSL and also have the benefit of being extremely fast. Another way is to use Authenticated Encryption like AES-GCM and AES-CCM instead of block mode with CBC. wolfSSL includes several cipher suites utilizing Authenticated Encryption algorithms. Lastly, wolfSSL implemented the countermeasures suggested in the paper in version 2.5.0 to avoid timing attacks.

Founded in 2004, wolfSSL offers open-source, embedded security solutions that are fast, small, portable and standard compliant including CyaSSL, the C-language SSL library for embedded and RTOS environments; yaSSL, the embedded C++ SSL library; and yaSSL Embedded Web Server, a fast, embeddable, secure web server. Dual licensed, wolfSSL caters to the security applications in industrial automation, smart energy, surveillance, medical, military, telecommunications markets and the open-source community. Distributed worldwide, wolfSSL is headquartered in Bozeman, Montana.

Release 2.5.0 of the wolfSSL lightweight SSL/TLS library has been released and is now available for download. This release has bug fixes and new features including:

– Fix for TLS CBC padding timing attack identified by Nadhem Alfardan and Kenny Paterson: http://www.isg.rhul.ac.uk/tls/
– Microchip PIC32 (MIPS16, MIPS32) support
– Microchip MPLAB X example projects for PIC32 Ethernet Starter Kit
– Updated CTaoCrypt benchmark app for embedded systems
– 1024-bit test certs/keys and cert/key buffers
– AES-CCM-8 crypto and cipher suites
– Camellia crypto and cipher suites
– Bumped minimum autoconf version to 2.65, automake version to 1.12
– Addition of OCSP callbacks
– STM32F2 support with hardware crypto and RNG
– Cavium NITROX support

CTaoCrypt now has support for the Microchip PIC32 and has been tested with the Microchip PIC32 Ethernet Starter Kit, the XC32 compiler and MPLAB X IDE in both MIPS16 and MIPS32 instruction set modes. See the README located under the /mplabx directory for more details.

To add Cavium NITROX support do:

./configure –with-cavium=/home/user/cavium/software

pointing to your licensed cavium/software directory. Since Cavium doesn`t build a library we pull in the cavium_common.o file which gives a libtool warning about the portability of this. Also, if you`re using the github source tree you`ll need to remove the -Wredundant-decls warning from the generated Makefile because the cavium headers don`t conform to this warning. Currently wolfSSL supports Cavium RNG, AES, 3DES, RC4, HMAC, and RSA directly at the crypto layer. Support at the SSL level is parital and currently just does AES, 3DES, and RC4. RSA and HMAC are slower until the Cavium calls can be utilized in non blocking mode. The example client turns on cavium support as does the crypto test and benchmark. Please see the HAVE_CAVIUM define.

wolfSSL is able to use the STM32F2 or STM32F4 hardware-based cryptography and random number generator through the STM32F2 Standard Peripheral Library. For necessary defines, see the CYASSL_STM32F2 define in settings.h. Documentation for the STM32F2 Standard Peripheral Library can be found in the following document:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/USER_MANUAL/DM00023896.pdf

The wolfSSL manual is available online or in PDF format. For build instructions and comments about the new features please check the manual. If you have any question, please contact us at info@yassl.com.