What is Hashing?

Hashing is the process of converting data of any size into a fixed-size string of characters, which usually looks like a sequence of random letters and numbers. The output of this process is called a hash.

How Hashing Works:

1. Input Data: You provide any data (like a file, password, or transaction) as input.
2. Hash Function: A hash function (e.g., SHA-256) is applied to the input. The hash function takes the input and processes it through a set of mathematical rules.
3. Fixed-Size Output: No matter how large or small the input is, the hash function will always produce a fixed-size output (called the "hash"). For example, with the SHA-256 algorithm, the output is always a 256-bit string.
4. Unique Output: Even a tiny change in the input data will result in a completely different hash. For example, changing a single letter in a file will produce a totally different hash.
5. One-Way: Hashing is a one-way function, meaning once the data is hashed, it’s nearly impossible to reverse-engineer the original input from the hash. This makes it useful for securing sensitive data like passwords.

Uses of Hashing:

• Data Integrity: Hashes are used to ensure data has not been altered. If two pieces of data have the same hash, it’s highly likely that they are identical.
• Cryptocurrency: Hashing is fundamental to blockchain technology. In Bitcoin, miners solve cryptographic puzzles by hashing large amounts of data to validate transactions and secure the network.
• Passwords: Instead of storing passwords, websites store hashes of passwords. When you log in, your input is hashed and compared with the stored hash to check if it matches.

Example:

Input: "hello"

Hash Output: 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 (using SHA-256)

Summary:

Hashing transforms data into a fixed-size, unique, and one-way output, making it essential for ensuring data integrity and security in various applications, including blockchain, file verification, and password storage.