Password Strength Checker & Generator — SecurePass (Local, No Server)

SecurePass — How we measure password strength (simple, accurate)

SecurePass helps you quickly see how strong a password is and gives a simple estimate of how long a modern attacker would take to crack it — all in your browser.

1) What this tool really does — very simple

• You type or paste a password, or ask it to make one.

• It looks at how long the password is and what kinds of characters are in it (small letters, big letters, numbers, symbols).

• From that it gives a number called entropy — think of it like “how many different keys could unlock this.” Bigger number = more keys = harder for bad guys.

• Then it says, “If a very fast machine tried all the keys one by one, how long would it take?” and shows an easy result (seconds / minutes / years).

• All of this happens in your browser. Nothing leaves your computer.

2) Very tiny examples — plain words + times (using a fast attacker as baseline)

I use one example attacker speed to keep things simple: a modern, very fast GPU cluster — call it super-fast machine. Think of it as trying 1,000,000,000,000 guesses every second (1 trillion guesses/sec). That’s fast, so times below are “if attacker is that fast.”

• Password: dog

  • This is very short and only small letters.

  • Result: instant (milliseconds). Bad.

• Password: password123

  • Longer, has letters + numbers.

  • Result: about 18 hours with that super-fast machine. So not safe for important accounts.

• Password: Tr0ub4dor&3

  • Mix of upper/lower/number/symbol.

  • Result: about 80 years. Pretty strong.

• Password: correcthorsebattery (a long phrase, only lowercase words)

  • Very long, easy to remember.

  • Result: many millions of years — basically safe against blind brute-force.

(These times are illustrative — they show scale only. Real attack speed depends on many things.)

3) Real stories where brute-force / guessing was important (what happened, when, why it mattered)

Story A — RockYou leak (2009) — big list of weak passwords got out

• What happened: A company’s database (RockYou) got stolen. Millions of plain-text passwords were published.

• Why brute-force mattered: Because attackers got a giant list of real passwords people actually used, they could try those same passwords on other sites and take over accounts. This is called credential stuffing.

• Why scary: People reuse passwords — one leak lets attackers break many other accounts quickly.

Story B — LinkedIn leak (2012, later big leaks) — hashed passwords cracked

• What happened: Hackers stole a big set of user passwords from LinkedIn. The passwords were hashed (a kind of scrambled form), but many were cracked by attackers later.

• Why brute-force mattered: Attackers used powerful computers to try huge numbers of guesses against those hashed values offline. Because hashing method and protections were weak, many common passwords were recovered.

• Why scary: After cracking, attackers could log into other services where people reused passwords.

Story C — Mirai & IoT device takeover (2016) — weak/default passwords on devices

• What happened: A malware called Mirai scanned the internet for cameras, routers, and other devices that still used default or very weak passwords. It logged in by trying those passwords and took over the devices.

• Why brute-force mattered: The malware simply tried common default username/password combinations at scale. No fancy exploit — just guessing and default creds.

• Why scary: The infected devices were used to launch huge DDoS attacks that brought down big websites.

4) Short plain takeaway — what to learn from this

• Short, common passwords = easy for attackers. Even “password123” is not safe.

• Length is your friend. Longer words or passphrases (even if only letters) often beat short mixed strings.

• Don’t reuse passwords. If one place leaks, attackers try those same credentials everywhere.

• Use MFA and slow hashing on servers. (For you: enable two-step verification wherever possible.)

• Use a password manager so you can have long, unique passwords without remembering them.

If you want, I can now:

• Give 3 super-short lines you can put under the generator (one-liners the user will understand instantly), or

• Make the same explanation in Hindi or Hinglish, or

• Add two super-simple example images (like “tiny clock = instant” “hourglass = hours” “big clock = years”) you can paste below the tool.

What the tool does (plain language)

• It measures how unpredictable your password is (that’s called entropy).

• It converts that unpredictability into how many guesses an attacker would need on average.

• It divides those guesses by a representative guesses-per-second value for a modern attacker to estimate time to crack.

• SecurePass runs in your browser — it does not send your password anywhere.

The simple formula (no heavy math)

1. Estimate the character set size used by the password (for example, lowercase+uppercase+digits+symbols ≈ 94).

2. Bits per character = log₂(character-set-size).

3. Total entropy (bits) = bits per character × password length.

4. Average guesses ≈ 2^(entropy − 1). (Attacker finds the right value halfway through on average.)

5. Time to crack = average guesses ÷ attacker_guesses_per_second → convert seconds to minutes/hours/years.

We compute big numbers using logarithms under the hood so the code never overflows and the results stay accurate.

Why we use a single “latest tech” baseline

To keep results meaningful and easy to compare, SecurePass shows estimates using one representative attacker speed: ≈ 1 × 10¹² guesses per second — a reasonable, conservative baseline for a modern multi-GPU cluster running optimized offline brute-force checks.
(If the service uses slow hashing like Argon2 or enforces login rate limits, real cracking would be much slower.)

Step-by-step examples (digit-by-digit so you can verify)

All calculations use the same method described above. I show the intermediate arithmetic so you can reproduce the numbers.

Example 1 — 12 characters, full printable set (~94 chars)

1. bits per character = log₂(94) ≈ 6.554588851677638.

2. Entropy = 12 × 6.554588851677638. Compute digit-by-digit:

   • 6.554588851677638 × 10 = 65.54588851677638

   • 6.554588851677638 × 2 = 13.109177703355276

   • Sum (×12) = 65.54588851677638 + 13.109177703355276 = 78.65506622013166 bits.

3. Average guesses ≈ 2^(78.65506622013166 − 1) = 2^77.65506622013166.

   • Use logs: log₁₀(avg_guesses) = (entropy − 1) × log₁₀(2)

   • log₁₀(2) ≈ 0.3010299956639812

   • log₁₀(avg_guesses) ≈ 77.65506622013166 × 0.3010299956639812 ≈ 23.376504247532406

4. At 1×10¹² guesses/sec: log₁₀(seconds) = 23.376504247532406 − 12 = 11.376504247532406

   • seconds ≈ 10^11.376504247532406 ≈ 237,960,157,407.13 seconds

   • convert to years: 237,960,157,407.13 ÷ 31,536,000 ≈ 7,545.67 years.
     Result: ~7,546 years at 1×10¹² g/s (offline brute-force).

Example 2 — 16 characters, full printable set

1. bits per character = log₂(94) ≈ 6.554588851677638.

2. Entropy = 16 × 6.554588851677638:

   • ×10 = 65.54588851677638

   • ×6 = 39.32753311006583

   • Sum (×16) = 65.54588851677638 + 39.32753311006583 = 104.8734216268422 bits.

3. log₁₀(avg_guesses) = (104.8734216268422 − 1) × 0.3010299956639812 ≈ 31.2690156619312

4. log₁₀(seconds) = 31.2690156619312 − 12 = 19.2690156619312

   • seconds ≈ 10^19.2690156619312 ≈ 1.8578714541705 × 10¹⁹ seconds

   • years ≈ seconds ÷ 31,536,000 ≈ 589,127,173,443.21 years (≈ 589 billion years).
     Result: astronomically large — effectively uncrackable with modern offline brute-force.

Example 3 — 8 characters, lowercase only (26 chars)

1. bits per character = log₂(26) ≈ 4.700439718141093

2. Entropy = 8 × 4.700439718141093 = 37.603517745128744 bits.

3. log₁₀(avg_guesses) = (37.603517745128744 − 1) × 0.3010299956639812 ≈ 11.01875678810256

4. log₁₀(seconds) = 11.01875678810256 − 12 = −0.98124321189744

   • seconds ≈ 10^(−0.9812432) ≈ 0.1044 seconds
     Result: ~0.1 seconds at 1×10¹² g/s — effectively instant. (Short lowercase passwords are weak.)

What these numbers mean (practical interpretation)

• Entropy is exponential: every extra bit doubles attacker work. Even 2–3 extra characters can dramatically increase protection.

• Length wins: adding characters helps far more than substituting one symbol for another.

• Make it unique: reusing passwords is the easiest way to get hacked. Use a password manager.

• Server-side protections matter: if a website uses Argon2/bcrypt and rate-limits login attempts, real-world cracking will be far slower than these raw offline numbers.

Actionable tips (do this now)

1. Use passwords ≥12 characters for important accounts; prefer ≥16 for very sensitive accounts.

2. Use a mix of upper, lower, digits, and symbols (or use long passphrases).

3. Use a reputable password manager to generate and store unique passwords.

4. Enable multi-factor authentication (MFA) wherever possible.

Short FAQ (for readers)

Q: Are these crack times exact?
A: No — they are illustrative. They model an offline, blind brute-force attacker at 1×10¹² guesses/sec. Real-world time depends heavily on server hashing and rate limits.

Q: What does “bits” mean?
A: Bits measure unpredictability. Each additional bit doubles how much work an attacker must do.

Q: What about dictionary attacks?
A: Dictionary or targeted attacks are usually much faster than blind brute-force. Avoid common phrases and reused passwords.