139 lines
3.4 KiB
Go
139 lines
3.4 KiB
Go
package pubsub
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import (
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"fmt"
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pb "github.com/libp2p/go-libp2p-pubsub/pb"
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"github.com/libp2p/go-libp2p-core/crypto"
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"github.com/libp2p/go-libp2p-core/peer"
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)
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// MessageSignaturePolicy describes if signatures are produced, expected, and/or verified.
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type MessageSignaturePolicy uint8
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// LaxSign and LaxNoSign are deprecated. In the future msgSigning and msgVerification can be unified.
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const (
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// msgSigning is set when the locally produced messages must be signed
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msgSigning MessageSignaturePolicy = 1 << iota
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// msgVerification is set when external messages must be verfied
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msgVerification
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)
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const (
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// StrictSign produces signatures and expects and verifies incoming signatures
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StrictSign = msgSigning | msgVerification
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// StrictNoSign does not produce signatures and drops and penalises incoming messages that carry one
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StrictNoSign = msgVerification
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// LaxSign produces signatures and validates incoming signatures iff one is present
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// Deprecated: it is recommend to either strictly enable, or strictly disable, signatures.
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LaxSign = msgSigning
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// LaxNoSign does not produce signatures and validates incoming signatures iff one is present
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// Deprecated: it is recommend to either strictly enable, or strictly disable, signatures.
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LaxNoSign = 0
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)
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// mustVerify is true when a message signature must be verified.
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// If signatures are not expected, verification checks if the signature is absent.
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func (policy MessageSignaturePolicy) mustVerify() bool {
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return policy&msgVerification != 0
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}
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// mustSign is true when messages should be signed, and incoming messages are expected to have a signature.
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func (policy MessageSignaturePolicy) mustSign() bool {
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return policy&msgSigning != 0
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}
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const SignPrefix = "libp2p-pubsub:"
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func verifyMessageSignature(m *pb.Message) error {
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pubk, err := messagePubKey(m)
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if err != nil {
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return err
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}
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xm := *m
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xm.Signature = nil
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xm.Key = nil
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bytes, err := xm.Marshal()
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if err != nil {
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return err
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}
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bytes = withSignPrefix(bytes)
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valid, err := pubk.Verify(bytes, m.Signature)
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if err != nil {
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return err
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}
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if !valid {
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return fmt.Errorf("invalid signature")
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}
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return nil
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}
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func messagePubKey(m *pb.Message) (crypto.PubKey, error) {
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var pubk crypto.PubKey
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pid, err := peer.IDFromBytes(m.From)
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if err != nil {
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return nil, err
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}
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if m.Key == nil {
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// no attached key, it must be extractable from the source ID
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pubk, err = pid.ExtractPublicKey()
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if err != nil {
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return nil, fmt.Errorf("cannot extract signing key: %s", err.Error())
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}
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if pubk == nil {
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return nil, fmt.Errorf("cannot extract signing key")
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}
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} else {
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pubk, err = crypto.UnmarshalPublicKey(m.Key)
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if err != nil {
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return nil, fmt.Errorf("cannot unmarshal signing key: %s", err.Error())
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}
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// verify that the source ID matches the attached key
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if !pid.MatchesPublicKey(pubk) {
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return nil, fmt.Errorf("bad signing key; source ID %s doesn't match key", pid)
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}
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}
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return pubk, nil
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}
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func signMessage(pid peer.ID, key crypto.PrivKey, m *pb.Message) error {
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bytes, err := m.Marshal()
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if err != nil {
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return err
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}
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bytes = withSignPrefix(bytes)
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sig, err := key.Sign(bytes)
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if err != nil {
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return err
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}
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m.Signature = sig
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pk, _ := pid.ExtractPublicKey()
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if pk == nil {
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pubk, err := key.GetPublic().Bytes()
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if err != nil {
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return err
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}
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m.Key = pubk
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}
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return nil
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}
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func withSignPrefix(bytes []byte) []byte {
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return append([]byte(SignPrefix), bytes...)
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}
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