This free SHA256 online generator allows you to generate a SHA256 (32-byte) hash of any string or input value, which is then returned as a hexadecimal number of 64 digits.

SHA-256 is a member of the SHA-2 cryptographic hash functions designed by the NSA. SHA stands for Secure Hash Algorithm. Cryptographic hash functions are mathematical operations run on digital data by comparing the computed "hash" (the output from execution of the algorithm) to a known and expected hash value, a person can determine the data's integrity. A one-way hash can be generated from any piece of data, but the data cannot be generated from the hash. (BitcoinWiki)

SHA-256 or SHA-2 is the modern cryptographic standard for online security. The algorithm produces an almost-unique, fixed-size 256-bit (32-byte) hash value. It is usually represented as a hexadecimal number of 64 digits.

.It is suitable for password validation, challenge hash authentication, anti-tamper, digital signatures, etc.. SHA-1 and SHA-2 are two different versions. They differ in both constructions and in the bit-length of the signature. SHA-2 is one of the successor hash functions to SHA-1 and is one of the strongest hash functions available. SHA-256 is not much more complex to code than SHA-1 and has not yet been compromised in any way.

The basic idea behind cryptographic hashing is to take an arbitrary block of data and return a fixed “hash” value. It can be any data, of any size but the hash value will always be fixed.

- The hash functions must be computationally efficient. It is very important because if the computer processes a cryptographic hash function and receive the output in a very long period of time it will not be very practical. To be useful, hash functions must be computationally efficient.
- The most important idea about the hash function is that the output must not reveal any information about the input. This is called pre-image resistance. The cryptographic hashing algorithms can receive any kind of input. The input can include numbers, letters, words, or punctuation marks, a single character, a sentence from a book, a page from a book, or an entire book. The fixed output guarantees the security because if a longer input produced a longer output, then attackers would already have a seriously helpful clue when trying to discover someone’s private input. In addition, changing one character in a long string of text must result in a radically different digest. If a cryptographic hash function produced different outputs each time for the same input was entered, it would be against the whole point of hash functions.
- The hash function must have collision resistance meaning that it must be impossible to find two different inputs that produce the same output.
- Cryptographic hash functions must be deterministic. In other words, for any given input, a hash function must always give the same result. If you put in the same input a hash function must produce the same exact output. As mentioned above, the inputs to a hash function can be of any length. This means there are infinite possible inputs that can be entered into a hash function. Hash functions are part of information security methods. A hash function is simply a function that takes in input value and creates an output value deterministic of the input value. For any x input value, you will always receive the same y output value whenever the hash function is run. The best way to demonstrate hash function is with a modular function which is also called modular arithmetic or clock arithmetic. Modular functions are mathematical functions that, put simply, produce the remainder of a division problem.

## The SSL industry uses SHA-2 as its hashing algorithm for digital signatures.

The SHA-2 hash function is implemented in some widely used security applications and protocols, including TLS and SSL, PGP, SSH, S/MIME, and IPsec.

The SSL/TLS protocol enables secure transmission of data from one device to another across the internet. The SSL provides authentication. But the SSL/TLS protocol facilitates a connection using asymmetric encryption. This means there are two encryption keys that each handle one half of the process: a public key for encryption, and a private key for decryption. Every SSL certificate contains a public key that can be used by the client to encrypt data, and the owner of said SSL certificate securely stores a private key on their server which they use to decrypt that data and make it readable.

From 2016, SHA-2 is used as a hashing algorithm for digital signatures. SSL/TLS certificate uses that signature. SHA-2 will likely remain in use for at least five years. However, some unexpected attack against the algorithm could be discovered which would prompt an earlier transition.

A larger bit hash can provide more security because there are more possible combinations. But if two different values or files can produce the same hash, a collision will occur. Collisions are extremely dangerous because they allow two files to produce the same signature, thus, when a computer checks the signature, it may appear to be valid even though that file was never signed.

## The SHA-256 is used in the bitcoin network.

The SHA-256 algorithm supports the Bitcoin network. Since this hash function is one way it works perfectly for cryptocurrency and namely - Bitcoin.

The SHA-256 takes part in the mining process. The process of releasing new coins and introducing them into the current supply is called mining. Mining is performed by powerful computers that solve cryptographic tasks. It ensures that the network is secure and no hackers can interrupt the process or falsify payments.

Bitcoin uses the SHA-256 algorithm two times, which is called double-SHA-256. This is how the formula looks like:

**Previous Block Hash = SHA-256(SHA-256(Block Header))**

The merkle root is also created by SHA-256 and placed into the block header. A Merkle root is the hash of all the hashes of all the transactions that are part of a block in a blockchain network. In other words, it stores the data about all transactions performed in the network.

SHA-256 also takes part in the creation of Bitcoin addresses which are known as private keys and required to perform transactions between users. The address is a unique code that consists of random numbers. The created key should go through two algorithms – SHA-256 and RIPEMD160.

These two algorithms create an opportunity to create short private keys. If the public key includes 256 bits, the private one includes only 160 bits. This was made easier for the users to operate with shorter addresses.