Add a signature package and stsigtool CLI utility

cmd/stsigtool/main.go

@@ -0,0 +1,102 @@
+// Copyright (C) 2015 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package main
+
+import (
+	"flag"
+	"io/ioutil"
+	"log"
+	"os"
+
+	"github.com/syncthing/syncthing/lib/signature"
+)
+
+func main() {
+	log.SetFlags(0)
+	log.SetOutput(os.Stdout)
+
+	flag.Parse()
+
+	if flag.NArg() < 1 {
+		log.Println(`Usage:
+	stsigtool <command>
+
+Where command is one of:
+
+	gen
+		- generate a new key pair
+
+	sign <privkeyfile> <datafile>
+		- sign a file
+
+	verify <pubkeyfile> <signaturefile> <datafile>
+		- verify a signature
+`)
+	}
+
+	switch flag.Arg(0) {
+	case "gen":
+		gen()
+	case "sign":
+		sign(flag.Arg(1), flag.Arg(2))
+	case "verify":
+		verify(flag.Arg(1), flag.Arg(2), flag.Arg(3))
+	}
+}
+
+func gen() {
+	priv, pub, err := signature.GenerateKeys()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	os.Stdout.Write(priv)
+	os.Stdout.Write(pub)
+}
+
+func sign(keyname, dataname string) {
+	privkey, err := ioutil.ReadFile(keyname)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fd, err := os.Open(dataname)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer fd.Close()
+
+	sig, err := signature.Sign(privkey, fd)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	os.Stdout.Write(sig)
+}
+
+func verify(keyname, signame, dataname string) {
+	pubkey, err := ioutil.ReadFile(keyname)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	sig, err := ioutil.ReadFile(signame)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fd, err := os.Open(dataname)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer fd.Close()
+
+	err = signature.Verify(pubkey, sig, fd)
+	if err != nil {
+		log.Fatal(err)
+	}
+}