Hashing

Hashing is a fundamental concept in computer science and cryptography, involving the use of a hash function to transform data of any size into a fixed-size output, often called a hash value, hash code, or simply a hash. This process is typically irreversible, meaning it's computationally infeasible to recover the original data from the hash value. hashing is primarily used for data indexing, integrity checks, and data storage, where it enables efficient data retrieval, comparison, and security enhancements by creating a unique 'fingerprint' for the input data.

Hashing meaning with examples

• In a database, hashing is used to create an index for faster data retrieval. When a search query is executed, the system first calculates the hash of the search key. This hash value is then used to quickly locate the corresponding data record, reducing search time significantly, making lookups in the database fast.
• Password storage heavily relies on hashing. Instead of storing passwords in plain text, which would be a major security vulnerability, systems store a hash of the password. When a user attempts to log in, the system hashes the entered password and compares it to the stored hash value.
• File integrity verification uses hashing. A hash value is calculated for a file and stored. Later, another hash is calculated for the same file. If the two hash values match, it indicates that the file hasn't been altered or corrupted during transfer or storage, and thus the file is still integral.
• Data structures like hash tables utilize hashing to store and retrieve key-value pairs. The hash function determines the location (bucket or slot) within the table where a given key-value pair will be stored. The hash function can also resolve potential collisions and find the requested data in a fast, O(1) time.