feat(key-protocol/nssa)!: PQ resistance primitives for vsk/vpk for shared key agreement

[jonesmarvin8]

🎯 Purpose

Shifts LEE to a PQ secure scheme, Kyber-768, for the key agreement. This requires changing the viewing keys from secp256k1 related data structures to byte arrays that can be used to produce ML-KEM-768 encapsulation and decapsulation keys. Updated key protocol for viewing key changes.

⚙️ Approach

• Update key protocol to change vsk and vpk generation.
• Update shared key generation logic to use Kyber-768.
• Update specs.md portions related to key agreement (only these sections are included).

🧪 How to Test

Refactored to replace ECIES with Kyber. As such, all pre-existing tests should still work. Additionally, added kem_to_chacha20_round_trip to demonstrate encapsulation and decapsulation does not distort account data.

🔗 Dependencies

None.

🔜 Future Work

None.

📋 PR Completion Checklist

• Complete PR description
• Implement the core functionality
• Add/update tests
• Add/update documentation and inline comments

[Pravdyvy]

I see, that some keys grow in magnitude. It will be very interesting to look at performance.
Unfortunately still not in CI, but can be called easily with just bench after merging main.

[jonesmarvin8]

I see, that some keys grow in magnitude. It will be very interesting to look at performance. Unfortunately still not in CI, but can be called easily with just bench after merging main.

What do you mean they grow in magnitude?
vsk, vpk should be fixed sizes. And the resulting ephemeral public key from a key agreement should be fixed size as well.

vsk is 64-bytes
vpk is 1kb
ephemeral public key is 1kb.

[Pravdyvy]

I see, that some keys grow in magnitude. It will be very interesting to look at performance. Unfortunately still not in CI, but can be called easily with just bench after merging main.

What do you mean they grow in magnitude? vsk, vpk should be fixed sizes. And the resulting ephemeral public key from a key agreement should be fixed size as well.

vsk is 64-bytes vpk is 1kb ephemeral public key is 1kb.

I mean that they grew in comparison to main. vpk before was 33 bytes. It is interesting to see how it affects performance.