Explore the critical role of entropy in modern cryptography and IT systems in this 56-minute Black Hat conference talk. Delve into the importance of cryptographically strong random numbers for key generation and nonce inclusion. Examine the challenges of Pseudo Random Number Generators (PRNGs) and their reliance on entropy sources. Discover the impact of Perfect Forward Secrecy on entropy usage in TLS. Analyze entropy requirements and utilization across various systems, including Linux, FreeBSD, OpenSSL, OpenSSH, and OpenVPN. Learn about entropy consumption in different TLS modes and the quality of entropy sources in common hardware. Gain insights into the newly released open-source software, libentropy, which provides a unified interface for OpenSSL to manage entropy sources and report usage statistics. Explore topics such as NIST guidelines, entropy pools, entropy estimation, and quantum random number generators.