Security with Go

Hashing large files

In the previous hashing example, the entire file to be hashed was loaded into memory before hashing. This is not practical or even possible when files reach a certain size. Physical memory limitations will come into play. Because the hashes are implemented as a block cipher, it will operate on one chunk at a time without the need to load the entire file in memory at once:

package mainimport (   "crypto/md5"   "fmt"   "io"   "log"   "os")func printUsage() {   fmt.Println("Usage: " + os.Args[0] + " <filename>")   fmt.Println("Example: " + os.Args[0] + " diskimage.iso")}func checkArgs() string {   if len(os.Args) < 2 {      printUsage()      os.Exit(1)   }   return os.Args[1]}func main() {   filename := checkArgs()   // Open file for reading file, err := ...