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// Command sign makes and uses the Ed25519 key that updates are signed with
// (internal/signing): a release's SHA256SUMS.txt, which the Windows app
// checks before it installs a new version (internal/update), and the TUN
// service's executable, which the installed service checks before it
// replaces itself (internal/tunservice):
//
// go run ./tools/sign -keygen FILE write a new private key to FILE, print its public key
// go run ./tools/sign -public print the public key (for -ldflags -X ...signing.Key=)
// go run ./tools/sign FILE... write FILE.sig beside each file
//
// The private key comes from -key FILE, else from FIREFOX_VPN_SIGNING_KEY
// (base64, as CI holds it in a secret), else from the file named by
// FIREFOX_VPN_SIGNING_KEY_FILE. A key file holds the base64 seed on one
// line; keep it out of the repository (*.signing-key is ignored).
package main
import (
"crypto/ed25519"
"crypto/rand"
"encoding/base64"
"errors"
"flag"
"fmt"
"os"
"strings"
)
func main() {
keygen := flag.String("keygen", "", "write a new private key to this file")
keyFile := flag.String("key", "", "the private key file")
public := flag.Bool("public", false, "print the public key")
flag.Parse()
if err := run(*keygen, *keyFile, *public, flag.Args()); err != nil {
fmt.Fprintln(os.Stderr, "sign:", err)
os.Exit(1)
}
}
func run(keygen, keyFile string, public bool, files []string) error {
if keygen != "" {
_, priv, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
return err
}
if err := os.WriteFile(keygen, []byte(base64.StdEncoding.EncodeToString(priv.Seed())+"\n"), 0o600); err != nil {
return err
}
fmt.Println(publicKey(priv))
return nil
}
priv, err := loadKey(keyFile)
if err != nil {
return err
}
if public {
fmt.Println(publicKey(priv))
return nil
}
if len(files) == 0 {
return errors.New("name the files to sign")
}
for _, f := range files {
data, err := os.ReadFile(f)
if err != nil {
return err
}
sig := base64.StdEncoding.EncodeToString(ed25519.Sign(priv, data))
if err := os.WriteFile(f+".sig", []byte(sig+"\n"), 0o644); err != nil {
return err
}
}
return nil
}
func publicKey(priv ed25519.PrivateKey) string {
return base64.StdEncoding.EncodeToString(priv.Public().(ed25519.PublicKey))
}
func loadKey(file string) (ed25519.PrivateKey, error) {
text := os.Getenv("FIREFOX_VPN_SIGNING_KEY")
if file == "" && text == "" {
file = os.Getenv("FIREFOX_VPN_SIGNING_KEY_FILE")
}
if file != "" {
data, err := os.ReadFile(file)
if err != nil {
return nil, err
}
text = string(data)
}
if text == "" {
return nil, errors.New("no key: use -key, FIREFOX_VPN_SIGNING_KEY, or FIREFOX_VPN_SIGNING_KEY_FILE")
}
seed, err := base64.StdEncoding.DecodeString(strings.TrimSpace(text))
if err != nil || len(seed) != ed25519.SeedSize {
return nil, errors.New("the key is not a base64 Ed25519 seed")
}
return ed25519.NewKeyFromSeed(seed), nil
}
arblant