Support Ed25519 and Ed25519ph

[zamicol]

Paul currently supports Ed25519. We're hoping Paul will implement Ed25519ph soon: paulmillr/noble-ed25519#63

The W3C Web Cryptography API recommendation also omits Ed25519, so an external package that implements the Ed25519 primitive is used. The upcoming update FIPS 186-5 specifies Ed25519 support. (https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5-draft.pdf, section 7.8) Hopefully this will motivate Javascript to include Ed25519.

See also the Ed25519 Tool

• Support Ed25519ph Ed25519Tool#1
• https://cyphr.me/ed25519_tool/ed.html
• https://github.com/Cyphrme/ed25519_tool

[zamicol]

Also consider https://stackoverflow.com/questions/75008138/can-subtlecrypto-verify-use-a-digest-instead-of-the-original-message/75008139#75008139

May be reason enough to move to noble-curves fully after release.

We may have multiple "back end" support as well, but SubtleCrypto will be limited in capability.

[zamicol]

Also, we'll preserve the current style somewhere so that we have a SubtleCrypto backend that can be used.

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More detail:
It's bonkers that the Web Crypto API (Subtle Crypto) doesn't support digests.

Something along the lines of the following needs to be included in the README:

https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/verify

Algorithms like ES224, ES256, ES384, and ES512 are designed for use with digests, however, Javascript does not support the explicit design requirement and instead requires the full original message. Existing applications may require this feature and idiomatically use these algorithms as intentionally permitted by design.

Also, this is a problem for performance. For example, a digest may represent a 1 GB file and verifying a 256 bit digest is better for performance than re-hashing a 1 GB file. Go and other languages use digests for verification. This expectation is not outside of industry norms.

Is there a work around the SubtleCrypto restriction of requiring the full original message, without resorting to an external library like noble-curves?