What is Salting in Security? A Beginner's Guide With a Real Example
What is Salting?
A very simple definition: Salting is the process of adding a unique, random string of characters to a password before it gets hashed, so that even two users with the exact same password end up with completely different stored hashes.
Think of it like a fingerprint stamped onto every password before it goes into the oven. Two identical cookies (passwords) come out looking nothing alike once you've pressed a different unique stamp into each one first. That's the whole idea, and yes, it really is that simple once you strip away the jargon.
A salt itself isn't secret. It's stored right next to the hash in the database, in plain view. What it does is make every password unique enough that attackers can't take a shortcut by cracking one hash and reusing that crack against everyone else who happened to pick the same weak password (and someone always picks “password123,” every single time, in every database, like clockwork).
For the basics of how this fits into the wider field, the Scaler Cyber Security hub is a good starting point if any of this terminology feels new.
Why Do We Need Salting? The Problem with Plain Hashing
Hashing alone sounds secure. It converts a password into a fixed-length, irreversible string, so even if a database leaks, nobody can supposedly read the actual passwords. The problem is that plain hashing has a quiet flaw: the same input always produces the same output.
That sounds harmless until you remember how many people reuse “iloveyou” or “qwerty123” across the internet. If two users pick the same password, their unsalted hashes will be identical, sitting right next to each other in a breached database, basically waving a flag that says “we match, go ahead and crack us both at once.”
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Enter the rainbow table
A rainbow table is a precomputed list of passwords and their corresponding hashes, built ahead of time so an attacker doesn't need to compute anything live. They just look up the leaked hash and find the matching password instantly, the way you'd look up a word in a dictionary instead of sounding it out letter by letter.
Without a salt, this attack works at scale. Crack one common password's hash, and you've effectively cracked it for every account on every breached site that used the same weak password and skipped salting. With a unique salt per user, the attacker has to crack each hash individually, with its own salt, which turns an instant lookup into a slow, expensive, one-at-a-time grind. That difference alone is most of why salting exists.
Worth pairing this with a look at how encryption fits the bigger picture, since the two get confused a lot: the Scaler Encryption and Decryption guide covers that adjacent ground well. If you're building toward a security or networking career rather than just looking this up for an assignment, Scaler's free Computer Networks course is a reasonable next stop.
How Does Salting Work? (Step-by-Step)
Here's the actual sequence, stripped of any mystery:
• Generate a random salt: a unique string created fresh for every single password, usually 16 bytes or more, using a cryptographically secure random generator (not your average random() function, which is too predictable for this job)
• Concatenate the salt with the password: combine the user's plaintext password with the salt, typically by appending it
• Hash the combined value: run that combined string through a slow, adaptive hashing algorithm, never a fast one like plain SHA-256 on its own
• Store the salt and the resulting hash together: side by side in the database, since you'll need the exact same salt again to verify a login later
• Verify on login: when the user logs in again, pull their stored salt, combine it with whatever password they just typed, hash it the same way, and check if the new hash matches the stored one
Pseudo-code version
salt = generate_random_salt(16) // unique per user combined = password + salt hash = hash_function(combined) // e.g. bcrypt, Argon2id store(username, salt, hash) // both saved, side by side // On login: stored_salt, stored_hash = lookup(username) new_hash = hash_function(login_password + stored_salt) if new_hash == stored_hash: access_granted = True
Notice the password itself is never stored anywhere, not even temporarily in a recoverable form. Only the salt (public) and the hash (one-way, irreversible) sit in the database. According to OWASP's own Password Storage Cheat Sheet, modern password hashing functions such as Argon2id, bcrypt, and PBKDF2 all require a salt as part of the algorithm itself, and most well-built libraries handle the salt generation automatically so developers don't have to roll their own (please don't roll your own crypto, genuinely, nobody needs that stress).
Salting Example: Same Password, Different Hashes
Here's the part that makes it click. Two users, same exact password, completely different stored hashes because of the salt.
| User | Password | Salt (stored, not secret) | Resulting Hash (illustrative) |
|---|---|---|---|
| User A | Sunshine99! | f3a9c1e7b2d84e0a | 9d2f...e41a (unique to this salt) |
| User B | Sunshine99! | 7b1e44a09cf32d6e | 3c8b...90f7 (completely different) |
Same password, same hashing algorithm, zero resemblance between the two stored hashes. An attacker who somehow cracks User A's hash learns nothing useful about User B's password, even though they typed the exact same string at signup. That's the entire point, demonstrated in one small table.
Salting vs Hashing vs Encryption
These three terms get tangled together constantly, including by people who really should know better by now.
| Salting | Hashing | Encryption | |
|---|---|---|---|
| What it does | Adds randomness before hashing | Converts data to a fixed-length value | Transforms data using a key, reversibly |
| Reversible? | N/A (it's an input, not a transform) | No, one-way function | Yes, with the correct key |
| Purpose | Defeats rainbow tables and duplicate-password leaks | Verify data integrity, store passwords safely | Protect data that must be read again later |
| Typical use case | Used alongside password hashing | Password storage, checksums | Storing addresses, payment data, messages in transit |
Per OWASP's guidance directly, passwords should be securely hashed using modern, adaptive hashing algorithms rather than encrypted or stored in plaintext, precisely because hashing is one-way and encryption isn't. If a password is ever encrypted instead of hashed, that's a design red flag, not a clever extra layer of security.
For the cryptography fundamentals underneath all of this, the Scaler Cryptography and Network Security guide goes into more depth than a single comparison table reasonably can.
Salt vs Pepper: What's the Difference?
Once salting clicks, “pepper” shows up and confuses everyone all over again. Fair, the naming is doing this on purpose.
• Salt: unique per user, stored right alongside the hash in the database, not secret, exists to defeat rainbow tables and stop duplicate passwords from looking identical
• Pepper: a single secret value, typically shared across the whole system, deliberately kept out of the database entirely (in a secrets vault or hardware security module instead)
OWASP describes peppering as an additional layer used alongside salting, one that specifically protects against an attacker who has only gained access to the database itself, say through a SQL injection or a stolen backup, without also compromising the application server where the pepper lives. A pepper alone provides no security benefit; it only adds defense in depth on top of proper salting and hashing, never as a replacement for either.
In short: salt is public and unique, pepper is secret and shared. Most systems get real, meaningful protection from salting alone; pepper is the extra padlock for people who want belt-and-suspenders security.
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• Use a unique salt for every single password, never reuse a salt across users, and never reuse the same salt for the same user across different hashes
• Generate salts using a cryptographically secure random number generator, not a standard pseudo-random function
• Use a sufficiently long salt, generally 16 bytes or more, so it isn't realistically guessable or repeatable across a large dataset
• Never roll your own hashing scheme. Use established adaptive algorithms: Argon2id, bcrypt, scrypt, or PBKDF2, all of which build salting directly into the algorithm
• Avoid fast hash functions like plain SHA-256 or MD5 for passwords specifically. They're built for speed, which is exactly the wrong property when the whole goal is to make cracking attempts slow and expensive
• Store the salt next to the hash, not separately, and don't try to keep it secret. Its job is uniqueness, not secrecy
NIST's SP 800-63B digital identity guidelines (pages.nist.gov/800-63-3/sp800-63b.html) require salts of at least 32 bits, generated using an approved random bit generator, and recommend a memory-hard function such as PBKDF2 with an appropriately tuned iteration count for verifier-side password storage. OWASP's Password Storage Cheat Sheet goes further with concrete configuration numbers, recommending Argon2id with a minimum of 19 MiB of memory and an iteration count of 2 as the strongest current general-purpose option, with scrypt as the fallback when Argon2id isn't available.
If you want to actually practice implementing this rather than just reading about it, Scaler's full course catalogue has security-adjacent tracks, and the Academy programs go deeper still for anyone serious about a security or backend engineering career.
Where Salting Is Used in the Real World
• Web application authentication: nearly every modern login system, from small SaaS products to large platforms, salts and hashes passwords before storing them
• Operating system password files: Linux systems have stored salted password hashes in /etc/shadow for decades, a far cry from the plaintext-adjacent password files of early Unix
• Password managers and identity providers: services like Auth0, Okta, and Firebase Authentication apply salting internally as a baseline, non-negotiable security measure
• Frameworks with built-in handling: Django's password hasher, Spring Security's PasswordEncoder, and most modern auth libraries (bcrypt.js, Werkzeug security helpers) generate and manage salts automatically, so most developers never write this logic by hand anymore
• Database breach scenarios: this is the context where salting actually proves its worth. A breached, salted-and-properly-hashed database gives an attacker a pile of nearly useless data; a breached, unsalted one is closer to a phone book of plaintext passwords waiting to be looked up
For more on where this sits inside the broader cyber security landscape, the Scaler Cyber Security hub is the right next stop, and the Cryptography vs Steganography comparison is a good adjacent read if you're curious how data-hiding techniques differ from data-protection ones.
FAQs
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What is salting in cyber security?
Salting is the process of adding a unique, random string (the salt) to a password before hashing it, so that identical passwords produce completely different hashes once stored. It's a defense specifically against rainbow tables and bulk password-cracking attempts.
What is the difference between hashing and salting?
Hashing converts data into a fixed-length, irreversible value on its own. Salting adds randomness to the input before hashing happens, so the same password doesn't always produce the same hash. Salting isn't a replacement for hashing, it's an enhancement applied alongside it.
Is salting reversible?
No. Like hashing itself, salting is one-way. The salt is stored alongside the hash purely so the system can recombine it with a login attempt and re-verify the password later, not so anyone can reverse-engineer the original password from the stored hash.
Why is a unique salt used for each password?
A unique per-user salt guarantees that two users with the same password end up with different hashes. This blocks precomputed rainbow-table attacks and stops an attacker from cracking one hash and instantly knowing every other account that shares the same password.
What is the difference between salt and pepper?
A salt is unique per user and stored openly alongside the hash. A pepper is a single secret value, usually shared across the entire system, kept separately from the database (in a secrets vault, not a database column). Salt protects against duplicate-password leaks; pepper protects against an attacker who only compromised the database itself.
Which algorithms are recommended for salted password storage?
Adaptive, deliberately slow algorithms: Argon2id (the current top recommendation per OWASP), scrypt, bcrypt, and PBKDF2. All four handle salting as part of the algorithm itself and allow tuning a work factor that controls how computationally expensive each hash attempt is, which is exactly what keeps brute-force attacks slow and costly.
Last updated: June 2026. Reviewed by Scaler’s Software Testing faculty team.
