[2] The audio_entropyd project,[3] which is included in some operating systems such as Fedora, allows audio data to be used as an entropy source.
[8] OpenBSD has integrated cryptography as one of its main goals and has always worked on increasing its entropy for encryption but also for randomising many parts of the OS, including various internal operations of its kernel.
[clarification needed] This made depletion of random data by userland programs impossible on OpenBSD once enough entropy has initially been gathered.
[14] Because CryptoAPI is closed-source, some free and open source software applications running on the Windows platform use other measures to get randomness.
It was thought that the number of weak keys found would have been far higher if simple and often attacker determinable one-time unique identifiers had not been incorporated into the entropy of some of these systems.
[22] Modern CPUs and hardware often feature integrated generators that can provide high-quality and high-speed entropy to operating systems.
[26][27] On Linux system, one can install the rng-tools package[28] that supports the true random number generators (TRNGs) found in CPUs supporting the RDRAND instruction, Trusted Platform Modules and in some Intel, AMD, or VIA chipsets,[29] effectively increasing the entropy collected into /dev/random and potentially improving the cryptographic potential.
Administrators responsible for systems that have low or zero entropy should not attempt to use /dev/urandom as a substitute for /dev/random as this may cause SSL/TLS connections to have lower-grade encryption.
[32] Some software systems change their Diffie-Hellman keys often, and this may in some cases help a server to continue functioning normally even with an entropy bottleneck.
[33] On servers with low entropy, a process can appear hung when it is waiting for random characters to appear in /dev/random (on Linux-based systems).
For example, one could collect entropy from the computer's microphone, or by building a sensor to measure the air turbulence inside a disk drive.