libgocryptfs/internal/cryptocore/nonce.go
Jakob Unterwurzacher 6c3f97399a Rename internal "toggledlog" package to "tlog"
tlog is used heavily everywhere and deserves a shorter name.

Renamed using sed magic, without any manual rework:

   find * -type f -exec sed -i 's/toggledlog/tlog/g' {} +
2016-06-15 23:30:44 +02:00

45 lines
932 B
Go

package cryptocore
import (
"bytes"
"crypto/rand"
"encoding/binary"
"encoding/hex"
"fmt"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// Get "n" random bytes from /dev/urandom or panic
func RandBytes(n int) []byte {
b := make([]byte, n)
_, err := rand.Read(b)
if err != nil {
panic("Failed to read random bytes: " + err.Error())
}
return b
}
// Return a secure random uint64
func RandUint64() uint64 {
b := RandBytes(8)
return binary.BigEndian.Uint64(b)
}
type nonceGenerator struct {
lastNonce []byte
nonceLen int // bytes
}
// Get a random "nonceLen"-byte nonce
func (n *nonceGenerator) Get() []byte {
nonce := RandBytes(n.nonceLen)
tlog.Debug.Printf("nonceGenerator.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)
}
n.lastNonce = nonce
return nonce
}