-help mentions SHA512 hash

[balloon.git] / cmd / balloon / main.go

diff --git a/cmd/balloon/main.go b/cmd/balloon/main.go
index 7ba57af5b83d9b80bc878f6a4c395170efcc7a03..b7fd973b5874af07430ffca10b3420f1f8bc9e24 100644 (file)
--- a/cmd/balloon/main.go
+++ b/cmd/balloon/main.go
@@ -1,10 +1,31 @@
+/*
+balloon -- Balloon password hashing function
+Copyright (C) 2016-2019 Sergey Matveev <stargrave@stargrave.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with this program.  If not, see
+<http://www.gnu.org/licenses/>.
+*/
+
 package main
 
 import (
+       "crypto/rand"
        "crypto/sha512"
        "encoding/hex"
        "flag"
        "fmt"
+       "io"
+       "os"
 
        "go.cypherpunks.ru/balloon"
 )
@@ -13,10 +34,21 @@ 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.Usage = func() {
+               fmt.Fprintf(os.Stderr, "balloon -- Strengthen password with Balloon+SHA512\n\n")
+               flag.PrintDefaults()
+       }
        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)
        }