Hashing algorithms are cryptographic functions used to convert data into a fixed-length value, called a hash. Hashing is designed to protect data integrity, not to hide data like encryption.
What Hashing Does
Hashing takes an input (such as a password or file) and produces a unique digital fingerprint.
Key characteristics:
- The same input always produces the same hash
- Even a small change in input produces a very different hash
- Hashing is one-way (the original data cannot be recovered from the hash)
What Hashing Is Used For
Hashing is commonly used to:
- Protect stored passwords
- Verify data integrity
- Detect unauthorized data changes
- Support digital signatures and authentication systems
For example, systems store hashed passwords, not plain-text passwords.
How Hashing Works in Practice
When data is hashed:
- The original data is processed by a hashing algorithm
- A fixed-length hash value is generated
- The hash is stored or compared for verification
During login, the entered password is hashed again and compared to the stored hash.
Common Hashing Algorithms
MD5 (Message Digest 5)
- Fast but no longer secure
- Vulnerable to collisions
- Not recommended for security use
SHA-1 (Secure Hash Algorithm 1)
- Improved over MD5 but now considered weak
- Deprecated for most security applications
SHA-2 (SHA-256, SHA-512)
- Widely used and secure
- Common in modern systems and protocols
SHA-3
- Latest SHA standard
- Designed as an alternative to SHA-2
Hashing vs Encryption
| Feature | Hashing | Encryption |
|---|---|---|
| Reversible | No | Yes |
| Purpose | Integrity and verification | Confidentiality |
| Key required | No | Yes |
Why Hashing Is Important in Cybersecurity
Hashing helps organizations:
- Protect user credentials
- Detect file tampering
- Ensure data integrity
- Support secure authentication
Weak or outdated hashing algorithms increase the risk of credential compromise and data manipulation.
Hashing in Security Frameworks
Hashing is referenced in:
- NIST Cybersecurity Framework (Protect function)
- ISO/IEC 27001 (Cryptographic controls)
- CIS Controls (Data protection and secure authentication)
Using approved hashing algorithms strengthens compliance and security posture.
Summary
Hashing algorithms create a one-way, fixed-length representation of data that is used to protect integrity and authentication. They are essential to secure systems, applications, and user credentials.
