package signed import ( "errors" "fmt" "strings" "time" "github.com/Sirupsen/logrus" "github.com/docker/go/canonical/json" "github.com/docker/notary/tuf/data" ) // Various basic signing errors var ( ErrMissingKey = errors.New("tuf: missing key") ErrNoSignatures = errors.New("tuf: data has no signatures") ErrInvalid = errors.New("tuf: signature verification failed") ErrWrongMethod = errors.New("tuf: invalid signature type") ErrUnknownRole = errors.New("tuf: unknown role") ErrWrongType = errors.New("tuf: meta file has wrong type") ) // IsExpired checks if the given time passed before the present time func IsExpired(t time.Time) bool { return t.Before(time.Now()) } // VerifyExpiry returns ErrExpired if the metadata is expired func VerifyExpiry(s *data.SignedCommon, role string) error { if IsExpired(s.Expires) { logrus.Errorf("Metadata for %s expired", role) return ErrExpired{Role: role, Expired: s.Expires.Format("Mon Jan 2 15:04:05 MST 2006")} } return nil } // VerifyVersion returns ErrLowVersion if the metadata version is lower than the min version func VerifyVersion(s *data.SignedCommon, minVersion int) error { if s.Version < minVersion { return ErrLowVersion{Actual: s.Version, Current: minVersion} } return nil } // VerifySignatures checks the we have sufficient valid signatures for the given role func VerifySignatures(s *data.Signed, roleData data.BaseRole) error { if len(s.Signatures) == 0 { return ErrNoSignatures } if roleData.Threshold < 1 { return ErrRoleThreshold{} } logrus.Debugf("%s role has key IDs: %s", roleData.Name, strings.Join(roleData.ListKeyIDs(), ",")) // remarshal the signed part so we can verify the signature, since the signature has // to be of a canonically marshalled signed object var decoded map[string]interface{} if err := json.Unmarshal(*s.Signed, &decoded); err != nil { return err } msg, err := json.MarshalCanonical(decoded) if err != nil { return err } valid := make(map[string]struct{}) for i := range s.Signatures { sig := &(s.Signatures[i]) logrus.Debug("verifying signature for key ID: ", sig.KeyID) key, ok := roleData.Keys[sig.KeyID] if !ok { logrus.Debugf("continuing b/c keyid lookup was nil: %s\n", sig.KeyID) continue } // Check that the signature key ID actually matches the content ID of the key if key.ID() != sig.KeyID { return ErrInvalidKeyID{} } if err := VerifySignature(msg, sig, key); err != nil { logrus.Debugf("continuing b/c %s", err.Error()) continue } valid[sig.KeyID] = struct{}{} } if len(valid) < roleData.Threshold { return ErrRoleThreshold{ Msg: fmt.Sprintf("valid signatures did not meet threshold for %s", roleData.Name), } } return nil } // VerifySignature checks a single signature and public key against a payload // If the signature is verified, the signature's is valid field will actually // be mutated to be equal to the boolean true func VerifySignature(msg []byte, sig *data.Signature, pk data.PublicKey) error { // method lookup is consistent due to Unmarshal JSON doing lower case for us. method := sig.Method verifier, ok := Verifiers[method] if !ok { return fmt.Errorf("signing method is not supported: %s\n", sig.Method) } if err := verifier.Verify(pk, sig.Signature, msg); err != nil { return fmt.Errorf("signature was invalid\n") } sig.IsValid = true return nil }