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package main
import (
"encoding/hex"
"os"
"strings"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/exitcodes"
"github.com/rfjakob/gocryptfs/internal/readpassword"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// unhexMasterKey - Convert a hex-encoded master key to binary.
// Calls os.Exit on failure.
func unhexMasterKey(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
}
// handleArgsMasterkey looks at `args.masterkey` and `args.zerokey`, gets the
// masterkey from the source the user wanted (string on the command line, stdin, all-zero),
// and returns it in binary. Returns nil if no masterkey source was specified.
func handleArgsMasterkey(args *argContainer) (masterkey []byte) {
// "-masterkey=stdin"
if args.masterkey == "stdin" {
in := string(readpassword.Once(nil, nil, "Masterkey"))
return unhexMasterKey(in, true)
}
// "-masterkey=941a6029-3adc6a1c-..."
if args.masterkey != "" {
return unhexMasterKey(args.masterkey, false)
}
// "-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)
}
// No master key source specified on the command line. Caller must parse
// the config file.
return nil
}
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