demo · v133

JWK / SPKI round-trip

Generate an X25519 keypair, export the public key as JWK and SPKI, re-import, derive bits against another freshly-generated party. The pattern interop libraries (libsodium-bridge, age, IETF MLS) need on Day 1.

public key as JWK

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public key as SPKI (base64)

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click the button to run the round-trip.

what the demo exercises

const me  = await crypto.subtle.generateKey({ name: "X25519" }, true, ["deriveBits"]);
const you = await crypto.subtle.generateKey({ name: "X25519" }, true, ["deriveBits"]);
const jwk  = await crypto.subtle.exportKey("jwk",  me.publicKey);
const spki = await crypto.subtle.exportKey("spki", me.publicKey);
const re   = await crypto.subtle.importKey("jwk", jwk,
                  { name: "X25519" }, false, []);
const bits = await crypto.subtle.deriveBits(
  { name: "X25519", public: you.publicKey }, me.privateKey, 256);

see also