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package signed
import (
"errors"
"strings"
"time"
"github.com/Sirupsen/logrus"
"github.com/endophage/gotuf/data"
"github.com/endophage/gotuf/keys"
"github.com/jfrazelle/go/canonical/json"
)
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")
)
// VerifyRoot checks if a given root file is valid against a known set of keys.
// Threshold is always assumed to be 1
func VerifyRoot(s *data.Signed, minVersion int, keys map[string]data.PublicKey) error {
if len(s.Signatures) == 0 {
return ErrNoSignatures
}
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
}
for _, sig := range s.Signatures {
// method lookup is consistent due to Unmarshal JSON doing lower case for us.
method := sig.Method
verifier, ok := Verifiers[method]
if !ok {
logrus.Debugf("continuing b/c signing method is not supported for verify root: %s\n", sig.Method)
continue
}
key, ok := keys[sig.KeyID]
if !ok {
logrus.Debugf("continuing b/c signing key isn't present in keys: %s\n", sig.KeyID)
continue
}
if err := verifier.Verify(key, sig.Signature, msg); err != nil {
logrus.Debugf("continuing b/c signature was invalid\n")
continue
}
// threshold of 1 so return on first success
return verifyMeta(s, "root", minVersion)
}
return ErrRoleThreshold{}
}
func Verify(s *data.Signed, role string, minVersion int, db *keys.KeyDB) error {
if err := VerifySignatures(s, role, db); err != nil {
return err
}
return verifyMeta(s, role, minVersion)
}
func verifyMeta(s *data.Signed, role string, minVersion int) error {
sm := &data.SignedCommon{}
if err := json.Unmarshal(s.Signed, sm); err != nil {
return err
}
if !data.ValidTUFType(sm.Type, role) {
return ErrWrongType
}
if IsExpired(sm.Expires) {
logrus.Errorf("Metadata for %s expired", role)
return ErrExpired{Role: role, Expired: sm.Expires.Format("Mon Jan 2 15:04:05 MST 2006")}
}
if sm.Version < minVersion {
return ErrLowVersion{sm.Version, minVersion}
}
return nil
}
var IsExpired = func(t time.Time) bool {
return t.Before(time.Now())
}
func VerifySignatures(s *data.Signed, role string, db *keys.KeyDB) error {
if len(s.Signatures) == 0 {
return ErrNoSignatures
}
roleData := db.GetRole(role)
if roleData == nil {
return ErrUnknownRole
}
if roleData.Threshold < 1 {
return ErrRoleThreshold{}
}
logrus.Debugf("%s role has key IDs: %s", role, strings.Join(roleData.KeyIDs, ","))
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 _, sig := range s.Signatures {
logrus.Debug("verifying signature for key ID: ", sig.KeyID)
if !roleData.ValidKey(sig.KeyID) {
logrus.Debugf("continuing b/c keyid was invalid: %s for roledata %s\n", sig.KeyID, roleData)
continue
}
key := db.GetKey(sig.KeyID)
if key == nil {
logrus.Debugf("continuing b/c keyid lookup was nil: %s\n", sig.KeyID)
continue
}
// method lookup is consistent due to Unmarshal JSON doing lower case for us.
method := sig.Method
verifier, ok := Verifiers[method]
if !ok {
logrus.Debugf("continuing b/c signing method is not supported: %s\n", sig.Method)
continue
}
if err := verifier.Verify(key, sig.Signature, msg); err != nil {
logrus.Debugf("continuing b/c signature was invalid\n")
continue
}
valid[sig.KeyID] = struct{}{}
}
if len(valid) < roleData.Threshold {
return ErrRoleThreshold{}
}
return nil
}
func Unmarshal(b []byte, v interface{}, role string, minVersion int, db *keys.KeyDB) error {
s := &data.Signed{}
if err := json.Unmarshal(b, s); err != nil {
return err
}
if err := Verify(s, role, minVersion, db); err != nil {
return err
}
return json.Unmarshal(s.Signed, v)
}
func UnmarshalTrusted(b []byte, v interface{}, role string, db *keys.KeyDB) error {
s := &data.Signed{}
if err := json.Unmarshal(b, s); err != nil {
return err
}
if err := VerifySignatures(s, role, db); err != nil {
return err
}
return json.Unmarshal(s.Signed, v)
}
|
