RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v6]

[Andrew Haley]

On Wed, 15 Jan 2025 18:28:55 GMT, Andrew Haley <aph at openjdk.org> wrote:

> The main problem is, though, that there is little commentary in the code which explains how things are encoded. ...

I now see what's going on,

I suggest you add a comment, something like "The polynomials are processed in bit-reflected order for efficiency reasons. For an explanation of how this works, see Vinodh Gopal, Erdinc Ozturk, Wajdi Feghali, Jim Guilford, Gil Wolrich,
Martin Dixon. Optimized Galois-Counter-Mode Implementation on Intel®
Architecture Processor
http://web.archive.org/web/20130609111954/http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/communications-ia-galois-counter-mode-paper.pdf"

That satisfies all of the requirements for documenting the algorithm, which is substantially different from the one in the AES/GCM specification.

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PR Comment: https://git.openjdk.org/jdk/pull/20235#issuecomment-2595294015