Crypto has served an important role in securing sensitive data throughout the years, but ransomware has flipped this script on its head by leveraging crypto as a means to instead prevent users from accessing their own data. The crypto seen in ransomware covers a wide range of complexity of symmetric and asymmetric algorithms, but flaws in their implementation and key storage / transmission routines have left the door open for users to retrieve their data in certain cases. In this talk, I'll provide a glimpse into some of the more notable ransomware crypto implementations that have surfaced over the past few years and how their weaknesses were exploited by security researchers through reverse engineering and cryptanalysis.