What are Cryptographic Hashes?
Cryptographic hashes are specialized algorithms used to transform data into a fixed-size string of characters, which appears random. This transformation is performed in such a way that even a small change in the input will produce a significantly different output. The primary uses of cryptographic hashes in web application security include data integrity, authentication, and digital signatures.
Key Properties
- Determinism: The same input will always produce the same output.
- Fast Computation: Hashing should be computationally efficient.
- Pre-image Resistance: It should be infeasible to reverse-engineer the original input from the hash output.
- Collision Resistance: It should be unlikely for two different inputs to produce the same hash output.
- Small Changes Yield Large Differences: A minor alteration in the input should yield a drastically different output.
Applications in Web Security
Cryptographic hashes are widely used to store passwords securely, ensuring that even if the data is compromised, the original passwords remain protected. They are also used in digital signatures, enabling verification of the authenticity and integrity of messages and documents. Furthermore, hashes play a crucial role in blockchain technology and are fundamental in ensuring the integrity of transactions.