[Cryptography] How should we encrypt external mail attachments

[John Levine]

It appears that Jon Callas <jon at callas.org> said:
>
>
>> On Aug 1, 2021, at 11:59, John Levine <johnl at iecc.com> wrote:
>> 
>> My question is what algorithms to use? The file can be anything up to
>> several gigabytes so they should be reasonably fast. It's OK if the hash
>> and key are fairly large, since a few hundred or even a few thousand
>> bytes in a mail message is not a big deal these days.
>
>Both Intel and ARM CPUs have AES and SHA-256 in hardware. (And SHA-1, for completeness.)
>
>Why not those? I don't see a reason to go to something else. 

Seems reasonable to me, but I figured it couldn't hurt to ask people with more crypto expertise
than I have.

R's,
John