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package signed
import (
"errors"
"fmt"
"strings"
"time"
"github.com/docker/go/canonical/json"
"github.com/sirupsen/logrus"
"github.com/theupdateframework/notary/tuf/data"
"github.com/theupdateframework/notary/tuf/utils"
)
// Various basic signing errors
var (
ErrNoSignatures = errors.New("tuf: data has no signatures")
ErrInvalid = errors.New("tuf: signature verification failed")
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 data.RoleName) 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", sig.Method)
}
if err := verifier.Verify(pk, sig.Signature, msg); err != nil {
return fmt.Errorf("signature was invalid")
}
sig.IsValid = true
return nil
}
// VerifyPublicKeyMatchesPrivateKey checks if the private key and the public keys forms valid key pairs.
// Supports both x509 certificate PublicKeys and non-certificate PublicKeys
func VerifyPublicKeyMatchesPrivateKey(privKey data.PrivateKey, pubKey data.PublicKey) error {
pubKeyID, err := utils.CanonicalKeyID(pubKey)
if err != nil {
return fmt.Errorf("could not verify key pair: %v", err)
}
if privKey == nil || pubKeyID != privKey.ID() {
return fmt.Errorf("private key is nil or does not match public key")
}
return nil
}
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