Intel's Software Guard Extensions allows general-purpose computing platforms to run software in a trustworthy manner and securely handle encrypted data. To satisfy the technology's security goals, the external system memory must be cryptographically protected. A new hardware unit added to the processor's memory controller--the Memory Encryption Engine (MEE)--was recently developed to protect the confidentiality, integrity, and freshness of this external memory traffic, against eavesdropping and tampering. The MEE is a successful feat of real-world cryptographic engineering: it's the first time such cryptographic memory protection has been added to a widely deployed general-purpose processor.