in order to practice me working on Golang, I decided to start writing some small scripts that would I would probably be using every once in a while. One of them is a Password/Secret Generator. The code will be shown below.

How it works? #

The project is just a 73 lines of code function that’s run in the CLI with some flags being passed to that command. With the flags being:

length and that would have the length of the string that we want to generate. by default it’s 12.
upper indicating that the string should have Uppercase letters, this is enabled by default
lower indicating that the string should have lowercase letters, this is enabled by default
digits indicating that the string should have numbers, this isn’t enabled by default and should be passed as a flag --digits to the command when running
special indicating that the string should have special characters, like digits this isn’t enabled by default and should be passed as a flag --special to the command when running.

In order to get the most out of the command, we simply need to:

Build the pass-generator.go file into a binary by running go build pass-generator.go
Move the pass-generator binary to /usr/local/bin
And then run the following command

pass-generator --length 32 --upper --lower --digits --special

Keep in mind that only the --digits and --special flats are required here. But by running the command above the output would be something like

Q!`CFtnx^$6_9q}]Y:kjgpU0Akn]r2QB

Code #

# pass-generator.go
package main

import (
 "flag"
 "fmt"
 "math/rand"
 "time"
)

var (
 length     = flag.Int("length", 12, "Password length")
 useLower   = flag.Bool("lower", true, "Use lowercase letters")
 useUpper   = flag.Bool("upper", true, "Use uppercase letters")
 useDigits  = flag.Bool("digits", false, "Use digits")
 useSpecial = flag.Bool("special", false, "Use special characters")
)

const (
 lowercase = "abcdefghijklmnopqrstuvwxyz"
 uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 digits    = "0123456789"
 special   = "!@#$%^&*()-_=+,.?/:;{}[]`~"
)

func generatePassword() string {
 var charset string

 if *useLower {
  charset += lowercase
 }

 if *useUpper {
  charset += uppercase
 }

 if *useDigits {
  charset += digits
 }

 if *useSpecial {
  charset += special
 }

 if charset == "" {
  panic("No character sets selected")
 }

 r := rand.New(rand.NewSource(time.Now().UnixNano()))
 password := make([]byte, *length)
 for i := range password {
  password[i] = charset[r.Intn(len(charset))]
 }

 return string(password)
}

func main() {
 flag.Parse()

 if *length <= 0 {
        fmt.Println("Error: Password length must be greater than 0.")
        return
    }

 if !(*useLower || *useUpper || *useDigits || *useSpecial) {
        fmt.Println("Error: At least one character set must be selected.")
  fmt.Println("Use -h for help.")
        return
    }

 password := generatePassword()
 fmt.Println(password)
}