Rethinking What Makes a Password Secure

Most people assume that a complex password with special characters, numbers, and mixed-case letters is the most secure option. Others believe that simply making passwords longer offers better protection. But which is truly more effective in today’s digital threat landscape?

Recent studies from cybersecurity researchers and real-world hacking attempts suggest it’s time to rethink what makes a password strong. In this article, we’ll break down the difference between password length and complexity, how they each impact security, and what you should focus on for ultimate protection.

Password Length vs. Password Complexity: What’s the Difference?

Understanding Length

Password length refers to the total number of characters in your password. A simple phrase like thisismypassword is long, but not necessarily complex.

Defining Complexity

Password complexity means using a mix of:

• Uppercase and lowercase letters

• Numbers

• Symbols and punctuation

An example of a complex but short password is T1&x@Qz!.

The Math Behind Password Security

Entropy: A Measure of Password Strength

Entropy measures the unpredictability of a password. Longer passwords and more complex combinations both raise entropy, but they do so differently. A 16-character password using only lowercase letters can be stronger than an 8-character password with every type of symbol.

Brute Force Resistance

A longer password increases the number of total combinations exponentially. For instance:

• An 8-character lowercase password has 208 billion possible combinations

• A 12-character lowercase password? 95 quintillion

• Add uppercase, numbers, and symbols? Now you’re in the sextillions or beyond

What Recent Studies Say: Length May Beat Complexity

Microsoft & NIST Research

Both Microsoft and the National Institute of Standards and Technology (NIST) now recommend long, memorable passwords over complex, hard-to-remember ones. They found that people are more likely to reuse or write down overly complex passwords, weakening overall security.

Password Cracking Simulations

Cybersecurity firm Hive Systems released a 2024 chart showing that:

• A 12-character password using only lowercase letters takes 300 years to crack

• An 8-character password with all character types can be cracked in under 8 hours. Length alone dramatically increases security—even without added complexity.

Why Humans Struggle with Complexity

Memory Limitations

Users tend to forget complex passwords. This leads to poor habits like:

• Writing passwords on paper

• Storing them in insecure notes apps

• Reusing a “strong” password across multiple sites

Password Fatigue

When required to remember multiple complex passwords, users often create patterns, like:

• Summer2024!

• Summer2025! Attackers know these tricks, and machine learning tools exploit them.

Longer Passwords Are Easier to Remember (When Done Right)

The Power of Passphrases

A passphrase is a string of unrelated words, like: coffee river galaxy train. It’s 26 characters long but easy to remember and type. Plus, it offers massive brute-force resistance.

Real-World Example

The famous correcthorsebatterystaple from xkcd’s comic demonstrates that length wins over complexity for real-world usage. It’s memorable, long, and resistant to cracking—even by AI.

How AI-Powered Crackers Handle Length vs. Complexity

AI Struggles with Long Random Phrases

AI models like PassGAN are trained on real password leaks. While they’re good at predicting common structures, they struggle with:

• Long, random phrases

• Unique combinations never seen before

Complexity Patterns Are Easier to Predict

Passwords like P@ssw0rd!23 are in millions of datasets. AI and ML tools recognise patterns faster than humans expect—making such “complex” passwords vulnerable.

Case Study: The Dropbox Password Leak

In 2022, a breach revealed that over 60% of leaked passwords were under 10 characters and followed predictable structures. Users who relied on long passphrases weren’t among the cracked accounts.

What Should You Focus On? Practical Takeaways

Prioritise Length First

Make your password at least 12–16 characters. Ideally, use a passphrase that’s both easy to remember and hard to guess.

Don’t Ignore Complexity Completely

While length is key, a long password with some complexity (a number or symbol) adds extra entropy. Just avoid predictable substitutions like 3 for e.

Use a Password Generator for Maximum Strength

Tools like YourPassGen can generate passwords with high entropy—combining length and complexity randomly, without predictable patterns.

Avoid Common Mistakes

• Don’t repeat passwords across sites

• Never use dictionary words alone

• Avoid sequential characters or personal info

Security Experts Agree: Password Length Wins in 2025

Top security analysts now advocate for passwords that are long, random, and unique for each account. This strategy, combined with two-factor authentication (2FA), can protect against even the most sophisticated AI-driven attacks.

The Verdict is In—Go Long, Not Just Complex

In the debate between password length and complexity, length has emerged as the more effective defence, especially when combined with randomness. Complex passwords can still play a role, but they often fall short if they’re short or predictable.

If you want to stay protected in 2025 and beyond, start with longer passwords, leverage secure generators like YourPassGen, and upgrade your security practices across the board.

Further Reading

• AI and Password Cracking: How Machine Learning is Changing the Threat Landscape

• Best Practices for Securing Your Google & Apple ID Passwords

• Password Safety on Public Wi-Fi