feat(evidence): publish retired-key rotation history in the JWK Set (v0.1.25.33)

cycles-protocol-service/cycles-protocol-service-api/src/main/java/io/runcycles/protocol/api/controller/JwksController.java

@@ -1,6 +1,9 @@
 package io.runcycles.protocol.api.controller;
 
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import io.runcycles.protocol.api.evidence.JwksDocuments;
+import io.runcycles.protocol.api.evidence.JwksDocuments.RetiredKey;
 import io.runcycles.protocol.data.exception.CyclesProtocolException;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
@@ -14,6 +17,8 @@
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
@@ -48,26 +53,98 @@ public class JwksController {
     private final String signerDid;
     private final String kid;
     private final long nbfMs;
+    private final List<RetiredKey> retiredKeys;
 
     public JwksController(
             @Value("${cycles.evidence.signing.signer-did:}") String signerDid,
             @Value("${cycles.evidence.signing.kid:}") String kid,
-            @Value("${cycles.evidence.signing.nbf-ms:0}") long nbfMs) {
+            @Value("${cycles.evidence.signing.nbf-ms:0}") long nbfMs,
+            @Value("${cycles.evidence.signing.retired-keys:}") String retiredKeysJson) {
         this.signerDid = signerDid == null ? "" : signerDid.trim();
         this.kid = kid == null ? "" : kid.trim();
         this.nbfMs = nbfMs;
+        this.retiredKeys = parseRetiredKeys(retiredKeysJson);
         if (!this.signerDid.isBlank() && !JwksDocuments.isRawHexKey(this.signerDid)) {
             LOG.info("evidence signer_did is not a raw 64-hex key (did:cycles or other); JWKS "
                     + "publication needs a raw-hex public key, so GET /v1/.well-known/cycles-jwks.json "
                     + "will return 404 until one is configured");
         }
+        if (!this.retiredKeys.isEmpty()) {
+            LOG.info("evidence JWKS: {} retired key(s) configured for rotation history", this.retiredKeys.size());
+            if (activeKeyWindowPredatesRetirement(this.nbfMs, this.retiredKeys)) {
+                LOG.warn("evidence JWKS: configured active key cycles_nbf_ms ({}) is at/before a retired key's "
+                        + "window end; the published active window is advanced to the latest retired exp so the "
+                        + "current key cannot resolve as valid for pre-rotation evidence. Set "
+                        + "cycles.evidence.signing.nbf-ms to the rotation time to make this explicit.", this.nbfMs);
+            }
+        }
+    }
+
+    /**
+     * True when the active key's {@code nbf-ms} starts before a retired key's
+     * window ends — i.e. retired keys exist (a rotation happened) but the active
+     * key's window was not advanced to the rotation time, so the active key is
+     * still published as authoritative for pre-rotation {@code issued_at_ms}.
+     */
+    static boolean activeKeyWindowPredatesRetirement(long activeNbfMs, List<RetiredKey> retired) {
+        long latestRetiredExp = retired.stream()
+                .filter(r -> r != null && r.expMs() != null && r.expMs() > r.nbfMs())
+                .mapToLong(RetiredKey::expMs)
+                .max()
+                .orElse(Long.MIN_VALUE);
+        return activeNbfMs < latestRetiredExp;
+    }
+
+    /**
+     * Parse {@code cycles.evidence.signing.retired-keys} — a JSON array of
+     * {@code {"signer_did","kid","nbf_ms","exp_ms"}} — into retired-key records.
+     * Malformed/incomplete entries are dropped here (logged) or skipped later by
+     * {@link JwksDocuments}; a parse failure yields no retired keys (the active
+     * key still publishes), never a crash.
+     */
+    private static List<RetiredKey> parseRetiredKeys(String json) {
+        if (json == null || json.isBlank()) {
+            return List.of();
+        }
+        List<RetiredKey> out = new ArrayList<>();
+        try {
+            JsonNode arr = new ObjectMapper().readTree(json);
+            if (!arr.isArray()) {
+                LOG.warn("cycles.evidence.signing.retired-keys is not a JSON array; ignoring");
+                return List.of();
+            }
+            for (JsonNode n : arr) {
+                JsonNode nbfNode = n.path("nbf_ms");
+                JsonNode expNode = n.path("exp_ms");
+                // Both window bounds MUST be explicit integral epoch-ms that fit in a
+                // long. A missing or non-integral nbf_ms is NOT coerced to 0 (epoch) —
+                // that would silently widen the validity window; and isIntegralNumber()
+                // alone accepts out-of-long-range integers that asLong() would wrap
+                // (e.g. 2^63 → Long.MIN_VALUE), so require canConvertToLong() too.
+                if (!nbfNode.isIntegralNumber() || !nbfNode.canConvertToLong()
+                        || !expNode.isIntegralNumber() || !expNode.canConvertToLong()) {
+                    LOG.warn("retired key '{}' has a missing/non-integral/out-of-range nbf_ms or exp_ms; skipping",
+                            n.path("kid").asText(""));
+                    continue;
+                }
+                out.add(new RetiredKey(
+                        n.path("signer_did").asText(""),
+                        n.path("kid").asText(""),
+                        nbfNode.asLong(),
+                        expNode.asLong()));
+            }
+        } catch (Exception e) {
+            LOG.warn("could not parse cycles.evidence.signing.retired-keys; ignoring: {}", e.getMessage());
+            return List.of();
+        }
+        return out;
     }
 
     @GetMapping(value = "/cycles-jwks.json", produces = MediaType.APPLICATION_JSON_VALUE)
     @Operation(operationId = "getEvidenceJwks",
             summary = "Fetch the signer's CyclesEvidence JWK Set (signer-key resolution)")
     public ResponseEntity<Map<String, Object>> getEvidenceJwks() {
-        Map<String, Object> jwks = JwksDocuments.jwkSet(signerDid, kid, nbfMs)
+        Map<String, Object> jwks = JwksDocuments.jwkSet(signerDid, kid, nbfMs, retiredKeys)
                 .orElseThrow(() -> CyclesProtocolException.notFound("cycles-jwks.json"));
         // Short, public cache — the set changes only on key rotation, so unlike a
         // content-addressed envelope it MUST NOT be immutable.

cycles-protocol-service/cycles-protocol-service-api/src/main/java/io/runcycles/protocol/api/evidence/JwksDocuments.java

@@ -1,11 +1,15 @@
 package io.runcycles.protocol.api.evidence;
 
+import java.util.ArrayList;
 import java.util.Base64;
+import java.util.HashMap;
 import java.util.HexFormat;
 import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.regex.Pattern;
 
 /**
@@ -15,17 +19,19 @@
  * (cycles-evidence v0.2). Pure function over the configured signing identity;
  * no Spring, no I/O.
  *
- * <p>v0.1 scope: publishes the single currently-configured RAW-HEX
- * {@code signer_did} as one active Ed25519 OKP JWK. A {@code did:cycles}
- * {@code signer_did} carries no key bytes, so it cannot be published from
- * {@code signer_did} alone — that (and retired-key rotation history) is the
- * v0.2-store follow-up; until then this returns {@link Optional#empty()} and
- * the endpoint 404s, leaving consumers on the raw-hex + {@code expected_signer}
- * pinning path.
+ * <p>Publishes the currently-configured RAW-HEX {@code signer_did} as the single
+ * ACTIVE Ed25519 OKP JWK (open-ended window), PLUS any configured RETIRED keys —
+ * each with a bounded {@code [cycles_nbf_ms, cycles_exp_ms)} window — so that
+ * evidence signed before a key rotation still verifies against the key that was
+ * valid at its {@code issued_at_ms}. Retaining retired keys is the load-bearing
+ * rotation rule: a verifier selects the key whose window covers the envelope's
+ * issuance time, never "the current key". A {@code did:cycles} {@code signer_did}
+ * carries no key bytes, so the active key cannot be published from it alone;
+ * the set is empty (endpoint 404s) until a raw-hex active key is configured.
  *
- * <p>Key bytes match what {@code EnvelopeSigner} signs with: the JWK {@code x}
- * is {@code base64url(hex-decode(signer_did))}, the same 32 raw public-key
- * bytes — so a verifier resolving this set authenticates the same signatures.
+ * <p>Key bytes match what {@code EnvelopeSigner} signs with: a JWK {@code x} is
+ * {@code base64url(hex-decode(<raw-hex pubkey>))}, the same 32 raw bytes — so a
+ * verifier resolving this set authenticates the same signatures.
  */
 public final class JwksDocuments {
 
@@ -34,41 +40,132 @@ public final class JwksDocuments {
     private JwksDocuments() {
     }
 
+    /**
+     * A previously-active signing key, retained in the published set so evidence
+     * signed during its validity window still resolves after rotation.
+     *
+     * @param signerDid the retired key as a raw 64-hex Ed25519 public key
+     * @param kid       its stable key id (must be unique across the set)
+     * @param nbfMs     valid-from (epoch ms, inclusive)
+     * @param expMs     valid-until (epoch ms, EXCLUSIVE) — REQUIRED for a retired
+     *                  key (a retired key has a closed window); a null exp is a
+     *                  config error and the entry is skipped.
+     */
+    public record RetiredKey(String signerDid, String kid, long nbfMs, Long expMs) {
+    }
+
     /** True when {@code signerDid} is a publishable raw 64-hex Ed25519 key. */
     public static boolean isRawHexKey(String signerDid) {
         return signerDid != null && RAW_HEX_32.matcher(signerDid.trim()).matches();
     }
 
+    /** Single active-key set (no rotation history). */
+    public static Optional<Map<String, Object>> jwkSet(String signerDid, String kid, long nbfMs) {
+        return jwkSet(signerDid, kid, nbfMs, List.of());
+    }
+
     /**
-     * The signer's JWK Set, or empty when no raw-hex signing key is configured
-     * (blank, or a {@code did:cycles} form that carries no key bytes).
+     * The signer's JWK Set — the active key plus any retired keys — or empty
+     * when no raw-hex active key is configured. Invalid retired entries are
+     * skipped defensively (a bad history entry never breaks publication of the
+     * active key): malformed hex; a missing {@code expMs} (a retired key needs a
+     * closed window); an empty/inverted window ({@code expMs <= nbfMs}, since
+     * {@code cycles_exp_ms} is EXCLUSIVE); the SAME key material as an earlier
+     * retired key with an OVERLAPPING window — raw-hex selection by key bytes
+     * plus {@code issued_at_ms} would be ambiguous, though disjoint windows for
+     * a reused key are fine; or a {@code kid} colliding with the active key or an
+     * earlier retired key (a duplicate {@code kid} is never emitted — set-wide
+     * kid uniqueness is required).
      *
-     * @param signerDid the configured {@code cycles.evidence.signing.signer-did}
-     * @param kid       configured key id, or blank to derive a stable default
-     * @param nbfMs     {@code cycles_nbf_ms} validity-from (epoch ms, inclusive)
+     * @param signerDid the active key ({@code cycles.evidence.signing.signer-did})
+     * @param kid       active key id, or blank to derive a stable default
+     * @param nbfMs     active {@code cycles_nbf_ms} (epoch ms, inclusive); if it
+     *                  was left below the latest retired key's {@code exp_ms} the
+     *                  published active window is advanced to that boundary, so the
+     *                  active key is never valid for pre-rotation {@code issued_at_ms}
+     * @param retired   retired keys to retain in the set (may be empty/null)
      */
-    public static Optional<Map<String, Object>> jwkSet(String signerDid, String kid, long nbfMs) {
+    public static Optional<Map<String, Object>> jwkSet(
+            String signerDid, String kid, long nbfMs, List<RetiredKey> retired) {
         if (!isRawHexKey(signerDid)) {
             return Optional.empty();
         }
-        String did = signerDid.trim();
-        byte[] publicKey = HexFormat.of().parseHex(did);
-        String x = Base64.getUrlEncoder().withoutPadding().encodeToString(publicKey);
+        String activeDid = signerDid.trim();
+        String activeKid = (kid == null || kid.isBlank()) ? defaultKid(activeDid) : kid.trim();
+
+        // Safety floor (fail-safe, not just a warning): the active key MUST NOT be
+        // published as valid before the latest retired key's window ends, or the
+        // current key could sign a backdated envelope (issued_at_ms before the
+        // rotation) that still resolves as authentic. If the configured nbf-ms was
+        // left below that boundary, advance the published active window up to it.
+        // Floor on EVERY declared bounded retired window — even one whose key
+        // material is malformed (so it won't be published): a typo in rotation
+        // history must not reopen the pre-rotation backdating hole on the active key.
+        long latestRetiredExp = (retired == null ? List.<RetiredKey>of() : retired).stream()
+                .filter(r -> r != null && r.expMs() != null && r.expMs() > r.nbfMs())
+                .mapToLong(RetiredKey::expMs)
+                .max()
+                .orElse(Long.MIN_VALUE);
+        long activeNbf = Math.max(nbfMs, latestRetiredExp);
+
+        List<Map<String, Object>> keys = new ArrayList<>();
+        Set<String> kids = new LinkedHashSet<>();
+        // Emitted [nbf, exp) windows per key material (lowercased hex), so the same
+        // key republished with an OVERLAPPING window is never emitted twice — raw-hex
+        // selection is key-bytes + issued_at_ms, which would otherwise be ambiguous.
+        // The active key needs no entry: the nbf clamp above puts its window at/after
+        // every retired exp, so it is always disjoint from a same-material retired key.
+        Map<String, List<long[]>> windowsByMaterial = new HashMap<>();
+        keys.add(buildJwk(activeDid, activeKid, activeNbf, null, "active"));
+        kids.add(activeKid);
 
+        if (retired != null) {
+            for (RetiredKey r : retired) {
+                if (r == null || !isRawHexKey(r.signerDid()) || r.expMs() == null) {
+                    continue; // malformed hex or no closed window — skip
+                }
+                long rNbf = r.nbfMs();
+                long rExp = r.expMs();
+                if (rExp <= rNbf) {
+                    continue; // empty or inverted window (exp is EXCLUSIVE) — skip
+                }
+                String rDid = r.signerDid().trim();
+                String material = rDid.toLowerCase();
+                List<long[]> seen = windowsByMaterial.get(material);
+                if (seen != null && seen.stream().anyMatch(w -> rNbf < w[1] && w[0] < rExp)) {
+                    continue; // same key material with an overlapping window (active or retired) — ambiguous, skip
+                }
+                String rKid = (r.kid() == null || r.kid().isBlank()) ? defaultKid(rDid) : r.kid().trim();
+                if (!kids.add(rKid)) {
+                    continue; // duplicate kid — never emit (set-wide uniqueness)
+                }
+                keys.add(buildJwk(rDid, rKid, rNbf, rExp, "retired"));
+                windowsByMaterial.computeIfAbsent(material, k -> new ArrayList<>()).add(new long[]{rNbf, rExp});
+            }
+        }
+
+        Map<String, Object> jwks = new LinkedHashMap<>();
+        jwks.put("keys", keys);
+        return Optional.of(jwks);
+    }
+
+    /** One Ed25519 OKP JWK. {@code expMs == null} ⇒ active (open-ended, exp
+     *  omitted); otherwise a bounded window with {@code status: retired}. */
+    private static Map<String, Object> buildJwk(String didHex, String kid, long nbfMs, Long expMs, String status) {
+        byte[] publicKey = HexFormat.of().parseHex(didHex);
         Map<String, Object> jwk = new LinkedHashMap<>();
         jwk.put("kty", "OKP");
         jwk.put("crv", "Ed25519");
         jwk.put("alg", "EdDSA");
-        jwk.put("x", x);
-        jwk.put("kid", (kid == null || kid.isBlank()) ? defaultKid(did) : kid.trim());
+        jwk.put("x", Base64.getUrlEncoder().withoutPadding().encodeToString(publicKey));
+        jwk.put("kid", kid);
         jwk.put("cycles_nbf_ms", nbfMs);
-        // cycles_exp_ms omitted ⇒ active (open-ended); `status` is advisory only —
-        // selection is by validity window, never by status.
-        jwk.put("status", "active");
-
-        Map<String, Object> jwks = new LinkedHashMap<>();
-        jwks.put("keys", List.of(jwk));
-        return Optional.of(jwks);
+        if (expMs != null) {
+            jwk.put("cycles_exp_ms", expMs);
+        }
+        // `status` is advisory only — selection is by validity window, never by status.
+        jwk.put("status", status);
+        return jwk;
     }
 
     /** Stable default key id when none is configured: the first 16 hex chars of

cycles-protocol-service/cycles-protocol-service-api/src/main/resources/application.properties

@@ -88,3 +88,15 @@ cycles.evidence.signing.signer-did=${EVIDENCE_SIGNING_SIGNER_DID:}
 # (epoch ms, inclusive; default 0 = valid since epoch, correct for a never-rotated key).
 cycles.evidence.signing.kid=${EVIDENCE_SIGNING_KID:}
 cycles.evidence.signing.nbf-ms=${EVIDENCE_SIGNING_NBF_MS:0}
+# Retired signing keys retained in the published set (rotation history) so
+# evidence signed before a rotation still verifies against the key valid at its
+# issued_at_ms. JSON array of {"signer_did":<raw 64-hex>,"kid":...,"nbf_ms":...,
+# "exp_ms":...}; exp_ms (EXCLUSIVE end of the key's window) is required per entry.
+# On rotation: set the new active key as signer-did, set nbf-ms (above) to the
+# rotation time, and append the old key here with exp_ms = that same rotation
+# time, so the windows meet without overlapping. If nbf-ms is left below the
+# latest retired exp_ms, the published active cycles_nbf_ms is warned on and
+# fail-safe clamped up to that boundary (so the active key cannot resolve for
+# pre-rotation issued_at_ms) — but set nbf-ms explicitly rather than relying on
+# the clamp. Empty = single active key (never rotated).
+cycles.evidence.signing.retired-keys=${EVIDENCE_SIGNING_RETIRED_KEYS:}