as per the FreeBSD announcement[0] and others[1][2] direct use of RDRAND as sole entropy source is not recommended. from Westmere onward you could use AES-NI to make crypto fast in OpenSSL. a common theme is to initialize OpenSSL via ENGINE_load_builtin_engines() which lets OpenSSL take advantage of this acceleration. with Sandy Bridge you also got RDRAND. now load_builtin_engines results in the application using RDRAND directly for all entropy, in addition to accelerating AES. if you are using an application linked with openssl-1.0.1-beta1 through openssl-1.0.1e you should do one of the following: a.) rebuild your OpenSSL with OPENSSL_NO_RDRAND defined. b.) call RAND_set_rand_engine(NULL) after ENGINE_load_builtin_engines(). c.) git pull latest openssl with commit: "Don't use rdrand engine as default unless explicitly requested." - Dr. Stephen Henson the OPENSSL_NO_RDRAND option is recommended; an inadvertent call to load engines elsewhere could re-enable this bad rng behavior. best regards, 0. "FreeBSD Developer Summit: Security Working Group, /dev/random" https://wiki.freebsd.org/201309DevSummit/Security 1. "Surreptitiously Tampering with Computer Chips" https://www.schneier.com/blog/archives/2013/09/surreptitiously.html 2. "How does the NSA break SSL? ... Weak random number generators" http://blog.cryptographyengineering.com/2013/12/how-does-nsa-break-ssl.html