How to Generate Strong Passwords: Security Best Practices

Why Password Security Matters

In 2023, over 24 billion username/password combinations were exposed in data breaches. The average person has 100+ online accounts, and 65% of people reuse passwords across multiple sites. A single compromised password can cascade into identity theft, financial loss, and unauthorized access to your entire digital life.

What Makes a Password Strong?

Password strength comes down to entropy — the number of possible combinations an attacker would need to try. Higher entropy = harder to crack.

The Math Behind Password Strength

Entropy (bits) = log2(charset_size ^ length)

Example: 8-character password with lowercase only
= log2(26^8) = 37.6 bits

Example: 16-character password with all character types
= log2(95^16) = 105.1 bits

Password Type	Charset	8 chars	12 chars	16 chars
Lowercase only	26	37.6 bits	56.4 bits	75.2 bits
+ Uppercase	52	45.6 bits	68.4 bits	91.2 bits
+ Numbers	62	47.6 bits	71.5 bits	95.3 bits
+ Symbols	95	52.6 bits	78.8 bits	105.1 bits

Key insight: Adding 4 characters to your password is more effective than adding symbols. A 16-character lowercase password (75.2 bits) is stronger than an 8-character password with all character types (52.6 bits).

How Password Cracking Works

Brute Force

Tries every possible combination. Modern GPUs can test:

• MD5: 180 billion hashes/second
• SHA-256: 23 billion hashes/second
• bcrypt (cost 12): 23,000 hashes/second

At 23 billion SHA-256 hashes/second:

Password	Time to Crack
6 chars, lowercase	0.01 seconds
8 chars, lowercase	3.5 minutes
8 chars, all types	19 hours
12 chars, lowercase	1,600 years
16 chars, lowercase	1.7 billion years

Dictionary Attacks

Uses lists of common passwords, words, and patterns. The top 10 most common passwords are still:

1. 123456
2. password
3. 123456789
4. 12345678
5. 12345
6. qwerty
7. abc123
8. 111111
9. password1
10. 1234567

If your password is on any common list, it will be cracked in milliseconds.

Rule-Based Attacks

Applies transformations to dictionary words: password → P@ssw0rd!, Password123, drowssap. These predictable substitutions (a→@, e→3, o→0) provide almost no additional security.

Password Best Practices

1. Use a Passphrase

Instead of a complex short password, use a long passphrase:

Bad:  P@ssw0rd!     (9 chars, 52.6 bits, crackable)
Good: correct-horse-battery-staple  (30 chars, very high entropy)
Good: purple-elephant-dancing-moonlight  (34 chars)

2. Make It Long

Minimum 12 characters, ideally 16+. Length is the single most important factor.

3. Make It Unique

Every account should have a different password. Use a password manager to handle this.

4. Use a Password Manager

Password managers generate, store, and auto-fill unique passwords for every site:

• Bitwarden — Open source, free tier
• 1Password — Excellent UX, family plans
• KeePass — Local-only, maximum control

5. Enable Two-Factor Authentication (2FA)

Even the strongest password can be phished. 2FA adds a second layer:

• Best: Hardware keys (YubiKey)
• Good: Authenticator apps (Authy, Google Authenticator)
• Acceptable: SMS codes (vulnerable to SIM swapping)

Check Your Password Strength

Use our Password Strength Checker to analyze any password. It checks:

• Length and character diversity
• Entropy calculation
• Common password detection
• Sequential and repeating pattern detection
• Estimated crack time

Generate strong passwords instantly with our Password Generator — it creates cryptographically secure passwords with customizable length and character sets.

For Developers: Storing Passwords Securely

Never store passwords in plain text. Always use a purpose-built hashing algorithm:

// ✅ Good: bcrypt with cost factor 12
const bcrypt = require("bcrypt");
const hash = await bcrypt.hash(password, 12);
const isValid = await bcrypt.compare(password, hash);

// ❌ Bad: MD5, SHA-256, or any fast hash
const hash = crypto.createHash("sha256").update(password).digest("hex");

Learn more about hashing in our guide: Understanding Hash Functions: MD5, SHA-256, and When to Use Each.

Related Tools

• Password Generator — Generate strong, random passwords
• Password Strength Checker — Analyze password security
• Hash Generator — Generate MD5, SHA-256, SHA-512 hashes
• HMAC Generator — Generate HMAC signatures
• Base64 Encoder — Encode and decode Base64 strings