example: add pass_strength/pass_strength.go (WTFPL licensed)

example/pass_strength/pass_strength.go

@@ -0,0 +1,102 @@
+// This is a small example using readline to read a password
+// and check it's strength while typing using the zxcvbn library.
+// Depending on the strength the prompt is colored nicely to indicate strength.
+//
+// This file is licensed under the WTFPL:
+//
+//         DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+//                     Version 2, December 2004
+//
+//  Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+//
+//  Everyone is permitted to copy and distribute verbatim or modified
+//  copies of this license document, and changing it is allowed as long
+//  as the name is changed.
+//
+//             DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+//    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+//
+//   0. You just DO WHAT THE FUCK YOU WANT TO.
+package main
+
+import (
+	"fmt"
+
+	"github.com/chzyer/readline"
+	zxcvbn "github.com/nbutton23/zxcvbn-go"
+)
+
+const (
+	Cyan          = 36
+	Green         = 32
+	Magenta       = 35
+	Red           = 31
+	Yellow        = 33
+	BackgroundRed = 41
+)
+
+// Reset sequence
+var ColorResetEscape = "\033[0m"
+
+// ColorResetEscape translates a ANSI color number to a color escape.
+func ColorEscape(color int) string {
+	return fmt.Sprintf("\033[0;%dm", color)
+}
+
+// Colorize the msg using ANSI color escapes
+func Colorize(msg string, color int) string {
+	return ColorEscape(color) + msg + ColorResetEscape
+}
+
+func createStrengthPrompt(password []rune) string {
+	symbol, color := "", Red
+	strength := zxcvbn.PasswordStrength(string(password), nil)
+
+	switch {
+	case strength.Score <= 1:
+		symbol = "✗"
+		color = Red
+	case strength.Score <= 2:
+		symbol = "⚡"
+		color = Magenta
+	case strength.Score <= 3:
+		symbol = "⚠"
+		color = Yellow
+	case strength.Score <= 4:
+		symbol = "✔"
+		color = Green
+	}
+
+	prompt := Colorize(symbol, color)
+	if strength.Entropy > 0 {
+		entropy := fmt.Sprintf(" %3.0f", strength.Entropy)
+		prompt += Colorize(entropy, Cyan)
+	} else {
+		prompt += Colorize(" ENT", Cyan)
+	}
+
+	prompt += Colorize(" New Password: ", color)
+	return prompt
+}
+
+func main() {
+	rl, err := readline.New("")
+	if err != nil {
+		return
+	}
+	defer rl.Close()
+
+	setPasswordCfg := rl.GenPasswordConfig()
+	setPasswordCfg.SetListener(func(line []rune, pos int, key rune) (newLine []rune, newPos int, ok bool) {
+		rl.SetPrompt(createStrengthPrompt(line))
+		rl.Refresh()
+		return nil, 0, false
+	})
+
+	pswd, err := rl.ReadPasswordWithConfig(setPasswordCfg)
+	if err != nil {
+		return
+	}
+
+	fmt.Println("Your password was:", string(pswd))
+}