Let’s All Agree to Use Seeds as ML-KEM Keys

This is a plea to the cryptography engineering community: let’s all agree to only use seeds as the storage format of ML-KEM keys, and forget that a serialized format for expanded decapsulation keys even exists. The ML-KEM expanded decapsulation key format is actually not even a good in-memory format, because it doesn’t include the full expanded matrix A but its seed ρ. The “Private Key Format” section of that draft doesn’t say what the actual private key format is, and hopefully it will land on 64-byte seeds.