Verifies the incoming JWS (Compact or General JSON Serialization) under its embedded oldKid (or an explicit override) and, if valid, produces a replacement signature with newKid. Useful for algorithm migrations without touching payload bytes.

Serialization selection (PRD §60). The optional serialization field selects the representation of the RE-SIGNED output (the incoming form does not govern it) and is orthogonal to the backend-authoritative RFC 3161 time-stamping policy (§49). Two honest compliance tiers: RFC 7515 JWS (COMPACT = §7.1 three-segment compact, or JSON = §7.2 JWS JSON Serialization) and JAdES B-T (JWS JSON Serialization only, carrying an RFC 3161 qualified timestamp sigTst in the Unprotected Header per ETSI TS 119 182-1 — a COMPACT token structurally cannot carry it).

Behavior truth table (serialization × effective stamping → output form):

An explicit COMPACT is never silently upgraded and a mandated stamp is never dropped; the output column names the logical serialization tier. On the HTTP wire the re-signed JWS is ALWAYS carried in the typed jwsToken (RFC 7515 §7.2 JWS JSON Serialization) envelope: a COMPACT / unstamped result is a single-signature object with no sigTst (losslessly convertible to the 3-segment compact form), a JAdES B-T result carries the RFC 3161 sigTst in the unprotected header. The re-sign metadata envelope (old/new key requested, per-leg material versions, algorithms, warnings) is ALWAYS present regardless of serialization.