Password Security: How to Create Uncrackable Passwords
Password security is one of the most important and most misunderstood topics in everyday digital life. Millions of accounts are compromised each year not because hackers are sophisticated, but because the passwords protecting them are weak or reused. This guide explains the science behind password strength, the methods attackers use, and how to create credentials that will realistically never be cracked.
What Makes a Password Strong?
Password strength is determined by entropy — the number of bits of uncertainty an attacker faces when trying to guess it. Entropy increases when you:
- Increase length (the single most powerful factor)
- Expand the character set (adding uppercase, numbers, and symbols)
- Avoid predictable patterns (dictionary words, keyboard walks like “qwerty,” personal information)
A truly random 12-character password using all character types (94 printable ASCII characters) has approximately 79 bits of entropy — enough to make brute-force attacks impractical on any current hardware. The Secure Password Generator creates cryptographically random passwords to this standard.
How Password Cracking Works
Attackers use several approaches, roughly in order of speed:
| Method | What it does | Defeated by |
|---|---|---|
| Dictionary attack | Tries every word in a wordlist, plus common substitutions | Not using real words |
| Brute force | Tries every possible character combination | Long passwords (length > 12) |
| Credential stuffing | Uses leaked username/password pairs from other breaches | Unique passwords per site |
| Rainbow table | Pre-computed hash lookup for common passwords | Salt + long unique password |
Use the Password Crack Time Estimator to see how quickly a given password would fall to a modern attack — the results are often sobering for short or predictable passwords and reassuringly large for longer random ones.
Password Length vs. Complexity: What Matters More?
Length wins, by a large margin. Adding one character to a password multiplies the possible combinations by the size of the character set (e.g., 94 for full ASCII). Going from 8 to 12 characters increases the search space by roughly 78 million times. By contrast, adding one symbol to a character set of 62 increases it by only about 1.5 times per position.
Practical rule: a 16-character all-lowercase random password is vastly stronger than an 8-character password with uppercase, numbers, and symbols — even though the shorter one looks more “complex.”
Passphrases: Strength Through Length
A passphrase is a sequence of randomly chosen words — for example, “correct horse battery staple” (from the famous XKCD comic). Four random common words give roughly 44 bits of entropy; six words exceed 77 bits, comparable to a strong random password but far easier to remember and type.
The key word is random. Choosing words yourself introduces patterns; using the Passphrase Generator draws from a large wordlist with a cryptographically secure random source, ensuring no word correlates with any other.
Random PINs for Codes and Security Questions
Numeric PINs are common for phones, bank cards, and access pads. A 4-digit PIN has only 10,000 possible combinations — a trivial brute-force target. A 6-digit PIN has 1,000,000, which is much better. A random 8-digit PIN has 100 million possibilities. For any application where a short numeric code is required, always avoid obvious patterns (1234, 0000, birth years, repeated digits) and use the Random PIN Generator to get a genuinely random value.
When to Use Which Generator
- Account passwords: use the Password Generator or Secure Password Generator for high-entropy random character strings, ideally stored in a password manager.
- Master passwords you must memorise: use the Passphrase Generator — longer and memorable.
- Device PINs, door codes, numeric access: use the Random PIN Generator.
Common Mistakes
- Reusing passwords. A single breach exposes every site where you used that password. Use a unique password for every account.
- Simple substitutions. Replacing “a” with “@” or “e” with “3” is in every attacker's dictionary — it adds almost no real entropy.
- Short “complex” passwords. Eight-character passwords, regardless of character variety, can be cracked in hours with modern hardware.
- Storing passwords in plain text. A password list in a Notes app or spreadsheet is a single breach away from total exposure. Use a dedicated password manager.
Frequently Asked Questions
How long should a password be in 2025?
For anything stored as a hashed credential (the standard for reputable services), 16 random characters is very strong and will not be cracked in your lifetime with any foreseeable technology. For master passwords you must remember, a 6-word random passphrase is equivalent and much easier to type.
What is the difference between the Password Generator and the Secure Password Generator?
Both use cryptographically secure random generation. The Secure Password Generator typically offers more control over character set composition and may apply additional security rules, while the standard Password Generator provides quick access to configurable-length random passwords.
Should I use special characters in passwords?
Yes, when the site allows them — they expand the character set and thus increase entropy per character. But never use them as a substitute for length. A 20-character lowercase password is stronger than an 8-character mixed-symbol password.
Is it safe to use online password generators?
Reputable browser-based generators that run entirely client-side (no server communication) are safe — the generated password never leaves your device. Avoid any generator that requires you to submit a form to a server.