How Passwords Work

Plaintext:

The simplest form of digital text, containing only basic characters like letters, numbers, and punctuation. Unencrypted and human-readable. Any sensitive information traveling online in plaintext is highly vulnerable.

Every time you sign in to your email, social media, or favorite shopping site, you’re performing a simple but powerful act of digital authentication. You type in your username and password, just a few characters that stand between your private world and everyone else on the internet. It feels routine, but behind the scenes, there’s a surprisingly complex process happening to make sure it’s really you logging in, not someone pretending to be you.

At its core, a password is like a digital key. It unlocks your account by proving your identity to a system that doesn’t actually “know” you, it just recognizes your credentials. When you first create an account, your password isn’t stored as plain text (at least it shouldn’t be). Instead, it’s transformed into something unrecognizable through a mathematical function called a hash. Think of hashing like a blender: once your password is processed through it, there’s no way to turn the resulting mix back into the original ingredients.

For example, if your password is BlueSky204, the website runs it through a hashing algorithm such as SHA-256 or bcrypt. That algorithm outputs a long, random looking string of letters and numbers, something like 8b2a7f4d9b6c3e91.... That hash is what’s stored in the website’s database, not your actual password. When you log in later, your typed password goes through the same hashing process again. If the resulting hash matches the one on file, you’re in. If it doesn’t, access is denied.

Hashing is one of the most important defenses in password security because it ensures that even if someone steals the website’s database, they won’t immediately see your real passwords. However, not all hashing methods are created equal. Older algorithms like MD5 or SHA-1 have been cracked or made obsolete by advances in computing power. That’s why modern systems use slower, more secure algorithms like bcrypt, SHA-256, or Argon2. These take more time to compute, which makes large scale password cracking much harder.

To make hashes even more secure, websites often use something called a salt which is a random value added to your password before hashing. This prevents attackers from using rainbow tables, which are massive precomputed lists of common passwords and their hashes. Without salts, if two people have the same password, they’ll have the same hash, a dead giveaway for hackers. With salts, even identical passwords produce different hashes, making stolen databases far less useful to attackers.

Now, here’s where it matters for regular users. While hashing and salts protect your passwords on the server, the biggest weakness is often you. People tend to reuse passwords across multiple sites, which means if one company suffers a breach, cybercriminals can take the stolen credentials and use them elsewhere. That’s why you might suddenly get a “suspicious login attempt” email from Netflix or Facebook after a completely unrelated website got hacked.

Passwords are a constant tug-of-war between convenience and security. The longer and more unique your password, the stronger it is, but the harder it is to remember. Attackers rely on this human weakness. They use automated tools to test billions of password combinations per second, starting with the most common ones: “123456”, “qwerty”, “password”, or even personal details scraped from social media. A password like “Jake2018” might feel suitable if that’s your dog’s name, but to an attacker, it’s a vulnerability.

When people hear that their passwords are “encrypted,” they often assume the website can decrypt them to read what they are. In reality, good systems never need to know your password, they just compare hashes. But not every organization follows best practices. There have been cases where companies stored passwords in plain text or used weak encryption, leading to massive leaks. The infamous LinkedIn and Adobe breaches exposed millions of unprotected credentials, teaching the world a hard lesson about why hashing matters.¹ ²

Modern login systems often use multi-factor authentication to add an extra layer of protection. This might mean typing a code sent to your phone, approving a push notification, or using a hardware security key. MFA ensures that even if your password is stolen, the attacker can’t get in without the second piece of proof. It’s like having a deadbolt on your digital front door.

Behind the scenes, authentication systems also keep an eye out for suspicious patterns. If someone tries to log in from a new country or an unfamiliar device, the system might block the attempt or ask for verification. This behavioral layer helps detect when a correct password is being used by the wrong person. It’s similar to a bouncer who knows your face, not just your name on the list.

At the end of the day, your password is your first line of defense, the handshake that proves who you are in a world of anonymous connections. Behind that simple login box lies a complex system of cryptography, algorithms, and trust. It’s invisible by design, but the more you understand it, the better equipped you are to keep your digital identity in your own hands.

¹ “Adobe Cyberattack 2013 Case Study”, by Kawushika, B, December 2023
² “Warning As 26 Billion Records Leak: Dropbox, LinkedIn, Twitter Named”, by Winder, D, January 2024