package signed // The Sign function is a choke point for all code paths that do signing. // We use this fact to do key ID translation. There are 2 types of key ID: // - Scoped: the key ID based purely on the data that appears in the TUF // files. This may be wrapped by a certificate that scopes the // key to be used in a specific context. // - Canonical: the key ID based purely on the public key bytes. This is // used by keystores to easily identify keys that may be reused // in many scoped locations. // Currently these types only differ in the context of Root Keys in Notary // for which the root key is wrapped using an x509 certificate. import ( "crypto/rand" "github.com/sirupsen/logrus" "github.com/theupdateframework/notary/trustmanager" "github.com/theupdateframework/notary/tuf/data" "github.com/theupdateframework/notary/tuf/utils" ) // Sign takes a data.Signed and a cryptoservice containing private keys, // calculates and adds at least minSignature signatures using signingKeys the // data.Signed. It will also clean up any signatures that are not in produced // by either a signingKey or an otherWhitelistedKey. // Note that in most cases, otherWhitelistedKeys should probably be null. They // are for keys you don't want to sign with, but you also don't want to remove // existing signatures by those keys. For instance, if you want to call Sign // multiple times with different sets of signing keys without undoing removing // signatures produced by the previous call to Sign. func Sign(service CryptoService, s *data.Signed, signingKeys []data.PublicKey, minSignatures int, otherWhitelistedKeys []data.PublicKey) error { logrus.Debugf("sign called with %d/%d required keys", minSignatures, len(signingKeys)) signatures := make([]data.Signature, 0, len(s.Signatures)+1) signingKeyIDs := make(map[string]struct{}) tufIDs := make(map[string]data.PublicKey) privKeys := make(map[string]data.PrivateKey) // Get all the private key objects related to the public keys missingKeyIDs := []string{} for _, key := range signingKeys { canonicalID, err := utils.CanonicalKeyID(key) tufIDs[key.ID()] = key if err != nil { return err } k, _, err := service.GetPrivateKey(canonicalID) if err != nil { if _, ok := err.(trustmanager.ErrKeyNotFound); ok { missingKeyIDs = append(missingKeyIDs, canonicalID) continue } return err } privKeys[key.ID()] = k } // include the list of otherWhitelistedKeys for _, key := range otherWhitelistedKeys { if _, ok := tufIDs[key.ID()]; !ok { tufIDs[key.ID()] = key } } // Check to ensure we have enough signing keys if len(privKeys) < minSignatures { return ErrInsufficientSignatures{FoundKeys: len(privKeys), NeededKeys: minSignatures, MissingKeyIDs: missingKeyIDs} } emptyStruct := struct{}{} // Do signing and generate list of signatures for keyID, pk := range privKeys { sig, err := pk.Sign(rand.Reader, *s.Signed, nil) if err != nil { logrus.Debugf("Failed to sign with key: %s. Reason: %v", keyID, err) return err } signingKeyIDs[keyID] = emptyStruct signatures = append(signatures, data.Signature{ KeyID: keyID, Method: pk.SignatureAlgorithm(), Signature: sig[:], }) } for _, sig := range s.Signatures { if _, ok := signingKeyIDs[sig.KeyID]; ok { // key is in the set of key IDs for which a signature has been created continue } var ( k data.PublicKey ok bool ) if k, ok = tufIDs[sig.KeyID]; !ok { // key is no longer a valid signing key continue } if err := VerifySignature(*s.Signed, &sig, k); err != nil { // signature is no longer valid continue } // keep any signatures that still represent valid keys and are // themselves valid signatures = append(signatures, sig) } s.Signatures = signatures return nil }