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Reversing the AMD Secure Processor (PSP) – Part 2: Cryptographic Co-Processor
Part one: https://dayzerosec.com/blog/2023/04/17/reversing-the-amd-secure-processor-psp.html This is a follow-up part 2 to my previous post on the AMD Secure Processor (formerly known as the Platform Security Processor or "PSP"). In that post, I mentioned that the Cryptographic Co-Processor (CCP) is an essential component of how the PSP functions. It's primarily responsible for hardware-accelerated cryptography, but it's also used as a Direct Memory Access (DMA) copy engine for doing mass copy
Descriptors are fairly straightforward, consisting mainly of a control word, length, and three pointers with encoded memory types for source, destination, and key information respectively. The "One Glitch to Rule Them All" paper [2] describes this at a high level, but let's go down the rabbit hole on the code responsible for retrieving and decrypting this component key and the firmware. Most of these CCP handlers look fairly similar, utilizing their respective macros to initialize the control bits and set up the request descriptor, so I won't do a deep dive on all of them.
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