I am using an IV in cipher.NewOFB, but my encrypted file never gets prefixed with it. I followed the golang examples at https://golang.org/pkg/crypto/cipher/, but can't seem to figure out why the prefix isn't being considered.
Does anyone see what the problem is?
func generateRandomIV(length int) []byte {
iv := make([]byte, aes.BlockSize)
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
panic(err)
}
return iv
}
func encryptFile(filename, keystring string) error {
readFile, err := os.Open(filename)
iv := generateRandomIV(aes.BlockSize)
outFile, err := os.OpenFile(filename+".enc", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
panic(err)
}
defer readFile.Close()
defer outFile.Close()
key := []byte(keystring)
block, err := aes.NewCipher(key)
if err != nil {
panic(err)
}
fmt.Println("IV:", iv)
writer := &cipher.StreamWriter{S: cipher.NewOFB(block, iv), W: outFile}
if _, err := io.Copy(writer, readFile); err != nil {
return err
}
return nil
}