Implements federationAuth.ts with generateHmacSecret, signRequest, verifySignature (constant-time, 15-minute replay window), buildFederationHeaders, and parseFederationHeaders for server-to-server federation authentication.
Implements federationAuth.ts with generateHmacSecret, signRequest, verifySignature (constant-time, 15-minute replay window), buildFederationHeaders, and parseFederationHeaders for server-to-server federation authentication.