Hashing is a cryptographic technique that transforms data of any size into a fixed-size output and is often used to ensure data integrity, digital signatures, or to store passwords.

What is hashing?

Hashing is a cryptographic process that transforms input data of any size into a fixed-length string of characters—called a hash. This output acts like a digital fingerprint for the data. Widely used in cybersecurity, hashing plays a critical role in verifying data integrity, securely storing passwords, and signing digital documents.

Where hashing is used in practice

Common use cases for hashing in business environments:

• File integrity verification – When downloading software, a hash is often provided so users can confirm the file wasn’t altered or corrupted.
• Password storage – Passwords are stored as hashes in databases, not in readable form. Even if breached, attackers can’t easily reverse the hash.
• Digital signatures – A document’s hash is encrypted with a private key to verify the sender and ensure the content hasn’t changed.
• Access control system – Hashed tokens or cookies are used to authenticate users in systems and apps.
• Change detection – Security software checks file hashes to detect unauthorized changes (e.g., caused by malware).

Hashing is invisible to most users but serves as a critical line of defense in maintaining trust and security across IT environments.

Hashing  vs. related terms

• Hashing vs. encryption – Hashing is one-way and irreversible; encryption is two-way and reversible with a key.
• Hashing vs. Checksum – A checksum is a simpler verification method vulnerable to tampering, while hashing is cryptographically secure.
• Hashing vs. salting – Salting adds random data before hashing to make the result more secure and prevent predictable outputs.

These differences are essential for choosing the right security approach. For example, password hashes should always be combined with salting and modern algorithms like bcrypt or Argon2 to resist brute-force attacks.

How to implement or audit hashing in your company

Kroky pro zavedení nebo kontrolu:

1. Audit password storage – Ensure passwords are stored as hashes, never in plain text.
2. Use modern algorithms – Avoid outdated options like MD5 or SHA-1; prefer SHA-256, bcrypt, or Argon2.
3. Apply salting – Strengthen password security by combining hashes with random salt values.
4. Use hashes for file integrity – Regularly check system files for unauthorized changes.
5. Train staff – Ensure developers and IT staff understand safe handling of hashes and where to store them.

Hashing may seem like a background process, but it’s a cornerstone of cybersecurity. Done poorly—such as using predictable hashes or insecure algorithms—it can leave systems vulnerable to serious threats without any warning. When done right, it quietly ensures the trustworthiness of systems, users, and data.