libgocryptfs/cryptfs/nonce.go

37 lines
701 B
Go
Raw Normal View History

2015-09-03 18:57:28 +02:00
package cryptfs
2015-09-03 18:22:18 +02:00
import (
"bytes"
2015-10-04 14:36:20 +02:00
"crypto/rand"
2015-09-03 18:22:18 +02:00
"encoding/hex"
2015-10-07 22:58:22 +02:00
"fmt"
2015-09-03 18:22:18 +02:00
)
// Get "n" random bytes from /dev/urandom or panic
func RandBytes(n int) []byte {
b := make([]byte, n)
2015-09-03 18:22:18 +02:00
_, err := rand.Read(b)
if err != nil {
panic("Failed to read random bytes: " + err.Error())
2015-09-03 18:22:18 +02:00
}
return b
}
var gcmNonce nonce96
type nonce96 struct {
lastNonce []byte
2015-09-03 18:22:18 +02:00
}
// Get a random 96 bit nonce
2015-09-03 18:22:18 +02:00
func (n *nonce96) Get() []byte {
nonce := RandBytes(12)
Debug.Printf("nonce96.Get(): %s\n", hex.EncodeToString(nonce))
if bytes.Equal(nonce, n.lastNonce) {
m := fmt.Sprintf("Got the same nonce twice: %s. This should never happen!", hex.EncodeToString(nonce))
panic(m)
2015-09-03 18:22:18 +02:00
}
n.lastNonce = nonce
return nonce
2015-09-03 18:22:18 +02:00
}