cmd/balloon/main.go | 13 +++++++++++--

diff --git a/cmd/balloon/main.go b/cmd/balloon/main.go
index 3576c4b14144d3e2166706b320408283d4e606935e5d05f03ecdb53925f35714..ba9c14eb922716971cfe62f5e921ae0c93712e0cc7d90bd8c22a195556b014d4 100644
--- a/cmd/balloon/main.go
+++ b/cmd/balloon/main.go
@@ -1,10 +1,12 @@
 package main
 
 import (
+	"crypto/rand"
 	"crypto/sha512"
 	"encoding/hex"
 	"flag"
 	"fmt"
+	"io"
 
 	"go.cypherpunks.ru/balloon"
 )
@@ -13,10 +15,17 @@ func main() {
 	s := flag.Int("s", 1<<18, "Space cost, number of hash-sized blocks")
 	t := flag.Int("t", 2, "Time cost, rounds")
 	p := flag.Int("p", 4, "Number of threads")
-	saltHex := flag.String("salt", "deadbabe", "Salt, hexadecimal")
+	saltHex := flag.String("salt", "", "Salt, hexadecimal, optional")
 	passwd := flag.String("passwd", "", "Password")
 	flag.Parse()
-	salt, err := hex.DecodeString(*saltHex)
+	var salt []byte
+	var err error
+	if len(*saltHex) == 0 {
+		salt = make([]byte, 8)
+		_, err = io.ReadFull(rand.Reader, salt)
+	} else {
+		salt, err = hex.DecodeString(*saltHex)
+	}
 	if err != nil {
 		panic(err)
 	}