Stage 5c: SIGNERS of 16 and 17 entries and two foreign signers in the part

Injected faults showed two rules that only the tests on the VM checked:
SIGNERS of more than 16 entries, whose only case was in security_cms.json,
and the order of the foreign signers. securitycms_vectors.json gains
SIGNERS of 16 and of 17 entries with Ana among them, beside her signature
for those SIGNERS or for SIGNERS with her alone, and a required signer
beside two foreign ones, without seals so that the area stays small; the
part for Node.js holds them. 760 cases.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tool/security_go_vectors.go

@@ -1996,6 +1996,9 @@ func signersOf(certs ...cmsCert) []byte {
 	return must(capsule.EncodeSigners(hashes))
 }
 
+// signersOfHashes is SIGNERS of the hashes, as EncodeSigners writes it.
+func signersOfHashes(hashes [][32]byte) []byte { return must(capsule.EncodeSigners(hashes)) }
+
 func cmsMessage(ctx int, signers []byte) []byte {
 	c := contexts[ctx]
 	return capsule.AuthorMessage(c.cc, c.hd, capsule.SignersDigest(capsule.AlgCMS, signers))
@@ -2145,6 +2148,37 @@ func cmsSecurityCases() {
 		addCMS("one signer", k.name, cmsArea(signers, signedData(*m.m), nil), c0)
 	}
 
+	// Two foreign signers, which show in the order of the encoding, beside a
+	// required one; without seals, so that the area stays small.
+	two := []cmsSigned{*required[9].m}
+	for _, c := range []cmsCert{otro, caducada} {
+		two = append(two, *memberOf(mA, kind{"", c, signOpts{}}).m)
+	}
+	addCMS("order", "Ana without seal, and two foreign signers without seal", cmsArea(signersA, signedData(two...), nil), c0)
+
+	// SIGNERS of 16 entries, the most, and of 17, with Ana among them, beside
+	// her signature over the AUTHOR_MESSAGE of those very SIGNERS, or of
+	// SIGNERS with her alone: 17 entries are F1, whatever the signature.
+	for _, n := range []int{16, 17} {
+		hashes := [][32]byte{sha256.Sum256(ana.raw)}
+		for i := 1; i < n; i++ {
+			hashes = append(hashes, digest(fmt.Sprintf("datekeys-dart: a certificate that signs nothing, %d", i)))
+		}
+		var e bytes.Buffer
+		e.Write(head(4, uint64(n)))
+		slices.SortFunc(hashes, func(a, b [32]byte) int { return bytes.Compare(a[:], b[:]) })
+		for _, h := range hashes {
+			e.Write(bstr(h[:]))
+		}
+		signers := e.Bytes()
+		if n == 16 && !bytes.Equal(signers, signersOfHashes(hashes)) {
+			panic("SIGNERS is not what EncodeSigners writes")
+		}
+		own := memberOf(cmsMessage(c0, signers), kind{"", ana, signOpts{token: sealed}})
+		addCMS("SIGNERS", fmt.Sprintf("SIGNERS of %d entries, Ana valid among them", n), cmsArea(signers, signedData(*own.m), nil), c0)
+		addCMS("SIGNERS", fmt.Sprintf("SIGNERS of %d entries, beside the signature of Ana for SIGNERS with her alone", n), cmsArea(signers, signedData(*required[1].m), nil), c0)
+	}
+
 	// B: three required signers, Ana, Luis and Beatriz, each absent or in
 	// one of her kinds, beside foreign signers, drawn from the seed.
 	signersB := signersOf(ana, luis, bea)