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 }