WebCrypto has Ed25519 but no ML-DSA, so the post-quantum half is
compiled from the same pkg/pqid the server verifies with. One
implementation of the scheme in the project means a client and server
cannot disagree about signing.
The Ed25519 half is stored as its 32-byte seed rather than the expanded
key, since the seed cannot encode an inconsistent pair, and the public
key is derived rather than stored so a client cannot present one that
does not match what it signs with.
Verified end to end in a JS runtime: 1984-byte public key, 3373-byte
signature, derived key matches, malformed input returns an error rather
than crashing the module. 3.4MB, 0.9MB gzipped.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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