Strong Random Passwords with Special Characters: What Actually Makes Them Secure

What makes a password "strong" in practice?

Password strength isn't just about length or throwing in an exclamation mark. It's about entropy — the number of possible combinations an attacker has to try. A password like P@ssw0rd looks complex but is weak because it follows a predictable pattern. Most cracking tools include rule-based attacks that substitute letters with similar-looking characters (a→@, o→0, s→$), so those substitutions add almost no real security.

True strength comes from randomness combined with a large character set. Here's how the math breaks down:

• Lowercase only (26 chars), 8 characters: ~200 billion combinations
• Upper + lower (52 chars), 8 characters: ~53 trillion combinations
• Upper + lower + digits + 32 special chars (94 chars), 12 characters: ~475 quadrillion combinations
• Same 94-char set, 16 characters: ~42 septillion combinations

Modern GPUs can test billions of password hashes per second. A 12-character password from a 94-character set takes years to brute-force. A 16-character one is effectively uncrackable with current hardware.

Which special characters should you include — and which can cause problems?

Most complexity requirements ask for at least one character from a set like !@#$%^&*()_+-=[]{}|;:,.<>?. But not all special characters behave the same across systems.

Commonly safe everywhere:

• !, @, #, $, %, ^, &, *, (, ), -, _, +, =

Occasionally problematic:

• ", ', ` — can break SQL queries or shell commands if the password is passed as a command-line argument
• \ — escape character in many contexts
• <, >, & — interpreted as HTML/XML in some web apps
• Spaces — often stripped or truncated

If you're generating passwords for command-line tools, SSH keys, or database connection strings, stick to alphanumeric plus -_!@#$%^*. For password managers (where you copy-paste), the full set is fine.

How do online password generators actually create random passwords?

Browser-based tools use crypto.getRandomValues(), the Web Cryptography API built into every modern browser. This is a cryptographically secure pseudorandom number generator (CSPRNG), the same class of randomness used in cryptographic key generation. It's fundamentally different from Math.random(), which is not cryptographically secure and shouldn't be used for passwords.

The process is straightforward: define a character pool (e.g., all 94 printable ASCII characters), then pick characters from that pool using cryptographically random indices. Repeat until you reach your desired length. A 16-character password from that pool needs only 16 random selections.

Tools that run entirely in your browser — like the Password Generator on JustUse.me — do this locally. Your password is never transmitted to a server. This matters because server-side generators, even trustworthy ones, create a network point where passwords could theoretically be logged or intercepted.

What complexity requirements do most systems actually enforce?

Corporate IT policies often follow NIST SP 800-63B or older standards. Here's what common requirements look like in practice:

Minimum typical requirements:

• At least 8 characters (NIST now recommends 15+)
• At least one uppercase letter
• At least one lowercase letter
• At least one digit
• At least one special character

Stricter enterprise requirements:

• 16+ characters
• No dictionary words
• No repeated characters (e.g., aaa)
• No sequential patterns (e.g., 123, abc)
• Expiration every 90 days (though NIST has moved away from recommending this)

When using a generator, look for one that lets you control these parameters explicitly — minimum counts per character type, excluded ambiguous characters (like 0, O, l, 1 which look alike), and custom character sets for unusual requirements.

Should you use a password manager or memorize generated passwords?

For almost every use case, store generated passwords in a password manager. Tools like Bitwarden (free, open source), 1Password, or KeePassXC handle storage securely. The only passwords worth memorizing are:

1. Your master password manager password
2. Your computer's login password
3. Possibly your primary email account password

For everything else, generate a unique 16-20 character random password and let the manager fill it in. Reusing passwords is the actual risk — when one site gets breached, attackers test those credentials everywhere else (credential stuffing).

How do you verify a password meets requirements before using it?

Some generators let you validate against rules in real time. If yours doesn't, you can check manually:

1. Count total length
2. Run it through a regex: (?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*[!@#$%^&*]) to confirm all character types are present
3. Check it against known breach databases using Have I Been Pwned's password checker (which uses k-anonymity, so your actual password isn't sent)

If you want to hash a password for storage in a system you're building, use Hash Generator to see how different algorithms (SHA-256, SHA-512) transform your input — useful for understanding how password storage works technically, though production systems should use bcrypt or Argon2, not raw SHA.

How do browser-based generators compare to desktop tools?

Smallpdf and iLovePDF are PDF tools that don't offer password generation. In the password generator space, tools like LastPass's built-in generator and Norton Password Generator are server-side — the randomness is generated on their servers, not your device. That's not inherently dangerous for most people, but it does mean your password passes through a third-party system.

Browser-local tools (including Password Generator) never send your password anywhere. The generation happens in your browser's JavaScript engine using crypto.getRandomValues(). For sensitive accounts — banking, work systems, email — that distinction is worth paying attention to.

Offline alternatives like KeePassXC's built-in generator or running openssl rand -base64 32 in a terminal are also fully local and worth knowing about.

What length should you actually use?

• 16 characters — solid default for most accounts
• 20 characters — good for high-value accounts (email, bank, password manager)
• 32+ characters — useful for API keys, service accounts, or anywhere the password is stored machine-to-machine and never typed

There's no meaningful downside to longer passwords in systems with proper storage. A 32-character password hashed with bcrypt takes no more time to verify than an 8-character one. Length is free security.

The practical takeaway: use a CSPRNG-based generator, include the full character set your target system supports, go with at least 16 characters, and store it in a password manager. That combination defeats brute-force attacks, dictionary attacks, and credential stuffing simultaneously.