Secure Hash Algorithm 2
(also SHA-2)
Secure Hash Algorithm 2 definition
Secure Hash Algorithm 2 (SHA-2) is a cryptographic method that transforms data into a unique, secure code. This code, called a hash value, is typically a string of numbers and letters. As hash values are unique for each input, this method is suitable for verifying data integrity, digital signatures, and other security uses.
SHA-2 is a one-way function, meaning it’s easy to compute the hash of an input but extremely difficult to derive the original input from the hash. Different variants of SHA-2 have different block sizes and hash lengths, but they all follow the same general principles.
See also: secure hash algorithm 1, hashing, hash function, hash chain, cryptographic hash function, integrity checking
How Secure Hash Algorithm 2 works
Secure Hash Algorithm 2 works by applying a series of cryptographic operations to input data, which produces a fixed-length hash value. Here’s a simplified overview of how SHA-2 works:
- Forming blocks. First, SHA-2 takes the input data and breaks it into small blocks.
- Padding. If needed, it adds some extra bits to the data so that the data can be divided into equal-sized blocks. This is called padding.
- Parsing. It then breaks the padded data into fixed-size blocks.
- Processing. SHA-2 processes each block, crunching it down to a much smaller size. It uses complex mathematical operations, including bitwise operations, modular arithmetic, and logical functions. This part mixes up the data so that even a tiny change in the original data will result in a completely different code.
- Output. After processing all the blocks, SHA-2 gives you a fixed-size code (e.g., 256 bits for SHA-256), which is unique to the original data.
Use cases of Secure Hash Algorithm 2
- Data integrity. It’s used to ensure that no one has tampered with the data during transmission or storage. Comparing the hash of received data with the original hash allows for detecting any changes or errors.
- Digital signatures. SHA-2 is a crucial component of digital signatures, where it helps verify the authenticity of a message or document.
- Password storage. It’s used for securely storing passwords. Instead of keeping the actual password, systems store the hash of the password. When a user logs in, the system compares the hash of the password they enter to the stored hash.
- Certificate authorities. SHA-2 is used to generate digital certificates for secure websites and online transactions.
- Blockchain. Many blockchain technologies use SHA-2 to create secure and tamper-proof transaction records.