hlverifier.gno

  1// Package hlverifier is the launch verifier of bridge/PLAN.md §5.1: the ed25519 check of the signers' signatures
  2// over a message's Hyperlane checkpoint, under the rule r/hlmailbox keeps beside its signer set — a threshold over
  3// the set, or §11.13's two groups (one key of group A and one of group B must sign). It registers itself with the
  4// mailbox at deploy and keeps no state: the signers and the rule are the mailbox's, read at every check, so a
  5// rotation there is a rotation here. Satisfiable answers whether a signer set could still meet the rule, which is
  6// what makes a signer's removal at once or a 7-day wait (§5.3).
  7package hlverifier
  8
  9import (
 10	"crypto/ed25519"
 11	"errors"
 12	"strconv"
 13
 14	hl "gno.land/p/g1zdaz6sypk5tdsjc2fzsqrrn4ttn8qzmnl4waqp/hyperlane/v0"
 15	"gno.land/r/g1zdaz6sypk5tdsjc2fzsqrrn4ttn8qzmnl4waqp/hlmailbox"
 16)
 17
 18const pkgPath = "gno.land/r/g1zdaz6sypk5tdsjc2fzsqrrn4ttn8qzmnl4waqp/hlverifier" // must match gnomod.toml
 19
 20// verifier is the hlmailbox.Verifier this realm registers.
 21type verifier struct{}
 22
 23func init(cur realm) {
 24	hlmailbox.RegisterVerifier(cross(cur), verifier{})
 25}
 26
 27// Verify checks the metadata — Hyperlane's checkpoint head (hook 32 ‖ root 32 ‖ index 4), then 65 bytes a
 28// signature: the signer's index in the set, then its ed25519 signature over the checkpoint digest of this message
 29// — and the rule: every signature present must verify, in increasing signer order, and the signers that signed
 30// must meet the rule.
 31func (verifier) Verify(origin uint32, metadata, message []byte) error {
 32	keys, rule := hlmailbox.Signers()
 33	if len(keys) == 0 {
 34		return errors.New("hlverifier: no signers")
 35	}
 36	m, err := hl.ParseMessage(message)
 37	if err != nil {
 38		return err
 39	}
 40	if m.Origin != origin {
 41		return errors.New("hlverifier: the message is from domain " + strconv.FormatUint(uint64(m.Origin), 10) + ", not " + strconv.FormatUint(uint64(origin), 10))
 42	}
 43	c, sigs, err := hl.ParseMultisigMetadata(metadata)
 44	if err != nil {
 45		return err
 46	}
 47	if len(sigs) == 0 {
 48		return errors.New("hlverifier: no signatures")
 49	}
 50	digest := hl.CheckpointDigest(m.Origin, c.Hook, c.Root, c.Index, hl.ID(message))
 51	var signed []hlmailbox.Key
 52	last := -1
 53	for _, s := range sigs {
 54		i := int(s.Validator)
 55		if i <= last {
 56			return errors.New("hlverifier: signatures out of signer order")
 57		}
 58		if i >= len(keys) {
 59			return errors.New("hlverifier: a signature names no signer")
 60		}
 61		k := keys[i]
 62		if !ed25519.Verify(k[:], digest[:], s.Sig[:]) {
 63			return errors.New("hlverifier: a signature does not verify")
 64		}
 65		signed = append(signed, k)
 66		last = i
 67	}
 68	if !satisfies(rule, signed) {
 69		return errors.New("hlverifier: the signatures do not meet the rule: " + rule.String())
 70	}
 71	return nil
 72}
 73
 74// Satisfiable is whether a signer set could meet the rule the mailbox keeps now: the threshold many of them, or
 75// one of each group among them.
 76func (verifier) Satisfiable(signers []hlmailbox.Key) bool {
 77	_, rule := hlmailbox.Signers()
 78	return satisfies(rule, signers)
 79}
 80
 81func satisfies(rule hlmailbox.Rule, signed []hlmailbox.Key) bool {
 82	if rule.TwoGroups() {
 83		return anyOf(rule.GroupA, signed) && anyOf(rule.GroupB, signed)
 84	}
 85	return rule.Threshold >= 1 && len(signed) >= rule.Threshold
 86}
 87
 88func anyOf(group, signed []hlmailbox.Key) bool {
 89	for _, g := range group {
 90		for _, s := range signed {
 91			if g == s {
 92				return true
 93			}
 94		}
 95	}
 96	return false
 97}
 98
 99// Registered is whether the mailbox holds this realm as a verifier.
100func Registered() bool { return hlmailbox.VerifierRegistered(pkgPath) }
101
102// Render: the rule enforced now.
103func Render(path string) string {
104	keys, rule := hlmailbox.Signers()
105	active := ""
106	if hlmailbox.ActiveVerifier(hlmailbox.LaunchOrigin()) == pkgPath {
107		active = "the active verifier"
108	} else {
109		active = "registered, not the active verifier"
110	}
111	return "# The ed25519 verifier\n\n" + active + " for origin " + strconv.FormatUint(uint64(hlmailbox.LaunchOrigin()), 10) +
112		": " + strconv.Itoa(len(keys)) + " signers in r/hlmailbox under the rule " + rule.String() + "\n"
113}