Day 3 - PassGuard | #30Days30Projects

Introduction

Passwords are our first line of defense on the web — but how strong is your password, really? Welcome to PassGuard, a simple yet powerful Java-based CLI tool that analyzes password strength using regex-based validations.

In this post, you’ll learn how to:

• Analyze password strength using Java

• Use regex patterns for validations

• Add colored outputs for a better CLI experience

• Build a fun and interactive CLI app in just under 100 lines

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🔧 Features of PassGuard

• Checks for length, uppercase, lowercase, digits, and special characters

• Gives a strength score and label (Weak, Medium, Strong)

• Provides a color-coded summary in the terminal

• Shows a detailed breakdown of what the password contains

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📁 Project Structure

PassGuard/
│
├── src/
│   └── PassGuard.java
└── README.md

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🧠 Concepts Used

• String manipulation

• Pattern and Matcher classes from java.util.regex

• ANSI escape codes for colored terminal output

• CLI input using Scanner

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🧑‍💻 The Complete Code

package PassGuard.src;

import java.util.Scanner;
import java.util.regex.Pattern;

public class PassGuard {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        // ANSI Color Codes
        final String RESET = "\u001B[0m";
        final String RED = "\u001B[31m";
        final String YELLOW = "\u001B[33m";
        final String GREEN = "\u001B[32m";
        final String CYAN = "\u001B[36m";
        final String BOLD = "\u001B[1m";

        // Header
        System.out.println(BOLD + CYAN + "╔═══════════════════════════════════════╗");
        System.out.println("║          Welcome to PassGuard         ║");
        System.out.println("╚═══════════════════════════════════════╝" + RESET);
        System.out.print("\nEnter a password to check strength: ");
        String password = sc.nextLine();

        // Score Calculation
        int strengthScore = 0;
        boolean hasLower = Pattern.compile("[a-z]").matcher(password).find();
        boolean hasUpper = Pattern.compile("[A-Z]").matcher(password).find();
        boolean hasDigit = Pattern.compile("[0-9]").matcher(password).find();
        boolean hasSpecial = Pattern.compile("[^a-zA-Z0-9]").matcher(password).find();
        boolean hasLength = password.length() >= 8;

        if (hasLength) strengthScore++;
        if (hasLower) strengthScore++;
        if (hasUpper) strengthScore++;
        if (hasDigit) strengthScore++;
        if (hasSpecial) strengthScore++;

        // Result Label
        String strengthLabel;
        String strengthColor;

        if (strengthScore <= 2) {
            strengthLabel = "Weak Password";
            strengthColor = RED;
        } else if (strengthScore <= 4) {
            strengthLabel = "Medium Password";
            strengthColor = YELLOW;
        } else {
            strengthLabel = "Strong Password";
            strengthColor = GREEN;
        }

        // Final Output
        System.out.println(BOLD + "\n──────────── Password Analysis ────────────" + RESET);
        System.out.println(strengthColor + BOLD + ">> " + strengthLabel + RESET);

        System.out.println(BOLD + "\n──────────── Detailed Breakdown ───────────" + RESET);
        System.out.printf("• %-13s: %s\n", "Length", hasLength ? GREEN + "Sufficient" : RED + "Too short" + RESET);
        System.out.printf("• %-13s: %s\n", "Lowercase", hasLower ? GREEN + "Present" : RED + "Missing" + RESET);
        System.out.printf("• %-13s: %s\n", "Uppercase", hasUpper ? GREEN + "Present" : RED + "Missing" + RESET);
        System.out.printf("• %-13s: %s\n", "Digits", hasDigit ? GREEN + "Present" : RED + "Missing" + RESET);
        System.out.printf("• %-13s: %s\n", "Special Char", hasSpecial ? GREEN + "Present" : RED + "Missing" + RESET);

        System.out.println(BOLD + "\nThank you for using PassGuard! Stay safe. " + RESET);
    }
}

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🖥 Sample Output

Input:

Enter a password to check strength: Hello@123

Output:

──────────── Password Analysis ────────────
>> Strong Password

──────────── Detailed Breakdown ───────────
• Length        : Sufficient
• Lowercase     : Present
• Uppercase     : Present
• Digits        : Present
• Special Char  : Present

Thank you for using PassGuard! Stay safe.

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🧪 How Password Strength is Calculated

Each of the following criteria gives 1 point:

• Length ≥ 8

• At least one lowercase letter

• At least one uppercase letter

• At least one digit

• At least one special character

Total out of 5

• 0–2: Weak

• 3–4: Medium

• 5: Strong

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🚀 How to Run It

1. Create the folder structure:

    mkdir -p PassGuard/src
    cd PassGuard/src
    touch PassGuard.java
   

2. Paste the code in PassGuard.java.

3. Compile & run:

    javac PassGuard.java
    java PassGuard
   

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💡 What You’ll Learn

• Regex pattern matching using Pattern.compile()

• Colored CLI output with ANSI codes

• Structuring and validating user input

• Creating mini-CLI utilities with Java

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✅ What's Next?

Try extending this:

• Add password suggestions

• Log password strength data to a file

• Add a GUI version using Java Swing or JavaFX

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📌 Final Thoughts

Even small projects like PassGuard teach a lot about real-world Java usage. Regex, CLI design, and user experience — all wrapped in one compact app.

If you're following the #30Days30Projects challenge, this is a great way to sharpen your Java fundamentals and show your work publicly.

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github repo - https://github.com/Rushi-Unge/30Days30Projects.git