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package main
import (
"encoding/hex"
"os"
"strings"
"golang.org/x/crypto/ssh/terminal"
"github.com/rfjakob/gocryptfs/internal/configfile"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/exitcodes"
"github.com/rfjakob/gocryptfs/internal/readpassword"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// printMasterKey - remind the user that he should store the master key in
// a safe place
func printMasterKey(key []byte) {
if !terminal.IsTerminal(int(os.Stdout.Fd())) {
// We don't want the master key to end up in a log file
tlog.Info.Printf("Not running on a terminal, suppressing master key display\n")
return
}
h := hex.EncodeToString(key)
var hChunked string
// Try to make it less scary by splitting it up in chunks
for i := 0; i < len(h); i += 8 {
hChunked += h[i : i+8]
if i < 52 {
hChunked += "-"
}
if i == 24 {
hChunked += "\n "
}
}
tlog.Info.Printf(`
Your master key is:
%s
If the gocryptfs.conf file becomes corrupted or you ever forget your password,
there is only one hope for recovery: The master key. Print it to a piece of
paper and store it in a drawer. Use "-q" to suppress this message.
`, tlog.ColorGrey+hChunked+tlog.ColorReset)
}
// parseMasterKey - Parse a hex-encoded master key that was passed on the command line
// Calls os.Exit on failure
func parseMasterKey(masterkey string, fromStdin bool) []byte {
masterkey = strings.Replace(masterkey, "-", "", -1)
key, err := hex.DecodeString(masterkey)
if err != nil {
tlog.Fatal.Printf("Could not parse master key: %v", err)
os.Exit(exitcodes.MasterKey)
}
if len(key) != cryptocore.KeyLen {
tlog.Fatal.Printf("Master key has length %d but we require length %d", len(key), cryptocore.KeyLen)
os.Exit(exitcodes.MasterKey)
}
tlog.Info.Printf("Using explicit master key.")
if !fromStdin {
tlog.Info.Printf(tlog.ColorYellow +
"THE MASTER KEY IS VISIBLE VIA \"ps ax\" AND MAY BE STORED IN YOUR SHELL HISTORY!\n" +
"ONLY USE THIS MODE FOR EMERGENCIES" + tlog.ColorReset)
}
return key
}
// getMasterKey looks at "args" to determine where the master key should come
// from (-masterkey=a-b-c-d or stdin or from the config file).
// If it comes from the config file, the user is prompted for the password
// and a ConfFile instance is returned.
// Calls os.Exit on failure.
func getMasterKey(args *argContainer) (masterkey []byte, confFile *configfile.ConfFile) {
masterkeyFromStdin := false
// "-masterkey=stdin"
if args.masterkey == "stdin" {
args.masterkey = string(readpassword.Once("", "Masterkey"))
masterkeyFromStdin = true
}
// "-masterkey=941a6029-3adc6a1c-..."
if args.masterkey != "" {
return parseMasterKey(args.masterkey, masterkeyFromStdin), nil
}
// "-zerokey"
if args.zerokey {
tlog.Info.Printf("Using all-zero dummy master key.")
tlog.Info.Printf(tlog.ColorYellow +
"ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING." +
tlog.ColorReset)
return make([]byte, cryptocore.KeyLen), nil
}
var err error
// Load master key from config file (normal operation).
// Prompts the user for the password.
masterkey, confFile, err = loadConfig(args)
if err != nil {
if args._ctlsockFd != nil {
// Close the socket file (which also deletes it)
args._ctlsockFd.Close()
}
exitcodes.Exit(err)
}
if !args.trezor {
readpassword.CheckTrailingGarbage()
}
if !args.fsck {
// We only want to print the masterkey message on a normal mount.
printMasterKey(masterkey)
}
return masterkey, confFile
}
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