SUMMARY
SHA-256, which stands for Secure Hash Algorithm, is a cryptographic hash function that converts any input data to a fixed alphanumeric string of 256 bits. Developed by the U.S. Government’s National Security Agency (NSA), SHA-256 is the most preferred cryptographic hash function for data security.
The hashing algorithm is considered highly secure as it generates unique and irreversible hash values. Thus, it is the most preferred security mechanism that is widely used in various security applications like digital signatures, password authentication, blockchain, cryptocurrencies, etc.
The Secure Hash Algorithm (SHA-256) is the most used hashing algorithm in cryptographic security. The algorithm processes the input data through a refined mathematical function, generating a unique output hash of a fixed size of 256 bits. The output hash is used as a digital signature as it depicts the original data.
The National Security Agency (NSA) in the United States introduced SHA-256 in 2001 as a successor to the SHA-1, which was vulnerable to attacks. Since the SHA-256 produces a fixed string of characters regardless of the input data, it is highly secure. For instance, the SHA-256 generates a hash of 256 bits long, making it computationally challenging for anyone to retrieve the original input from the hash value, keeping the data integrity intact.
SHA-256, as a secure hashing algorithm, processes the input data by passing it through a series of mathematical operations. The input can either be a four-letter password or many pages of a book — the SHA-256 algorithm creates the same 256-bit hash value.
Even if you make a slight change in the input, like one character, the output will be entirely different. Thus, it is highly challenging for attackers to reverse engineer the hash and find the original data, making the algorithm highly secure.
Let’s see the prominent characteristics of the SHA-256 algorithm.
The prime characteristic of the SHA-256 algorithm is its uniqueness of the output. Simply put, the algorithm generates the output hash value of 256 bits long, regardless of the input size. So, if it is a single character input or multiple pages of input, the output hash value will be 256 bits long.
All hash values generated by the SHA-256 algorithm are irreversible. Any input, regardless of the size, generates the same output with a fixed length of 256 bits. Moreover, the input size is not restricted. Thus, it is computationally impossible for hackers to reverse engineer the original data. That, in turn, ensures the original data is secure at all times, even if the hash value is available publicly.
The SHA-256 algorithm generates the same hash value for a specific input. That maintains consistency in the hashing process, which, in turn, enables users to verify data across remote systems.
Once you enter the input data, the SHA-256 algorithm processes it via a series of mathematical calculations known as rounds. The process involves multiple steps, like data preprocessing, message expansion, and message compression. Let’s see those steps in detail.
The entered input data is padded, which means adding a few extra bits to the original message. The bits are added in such a way that the first bit is one while the rest of it is zeroes. The padded data length is made sure of a multiple of 512.
The 512-bit input is divided into 16 32-bit words first. It is then expanded into 64 32-bit words via a series of mathematical operations.
The expanded 64-worded message is then processed through a series of 64 rounds involving the following steps.
Each round consists of a distinct 32-bit constant value produced depending on the position in the sequence.
A 64-entry message schedule is created based on the 64-worded message and the round constant.
The 8 32-bit words are the working variables that store the intermediate values during the hashing process. These working variables are updated based on the message schedule and a series of mathematical operations.
Once all the 64 rounds are done, the final values of the working variables are combined, and the 256-bit hash value is generated. The final output of the SHA-256 algorithm is always a 256-bit hash value, which acts as a digital signature of the input data.
The SHA-256 algorithm is widely used across various applications, including data security, blockchain, digital signatures, and more. Let’s see them in detail.
Digital or electronic signature is the most common application of the SHA-256 algorithm, which is used to validate the authenticity of messages like credit card transactions, digital documents, etc.
The SHA-256 algorithm generates a hash value of the original content, making it a unique digital signature. That way, the integrity of the message is protected at all times. The signer can encrypt the hash value by using the private key.
Password hashing is another famous use case of the SHA-256 algorithm. Organizations and institutions hesitate to store their passwords, fearing unethical activities. Thus, they derive their hash values. So, every time the user enters the password, the algorithm derives a new hash value and verifies whether it matches the original content stored in the database.
The SHA-256 algorithm is an irreplaceable hash function in blockchain applications. As we all know, the most popular cryptocurrency, Bitcoin, which follows the Proof of Work (PoW) mechanism, follows the SHA-256 algorithm to verify transactions, mine new blocks, and secure the network against attacks.
The SHA-256 algorithm secures the integrity of the data stored in the blocks, as each block contains a unique digital fingerprint that cannot be changed. Moreover, each block is linked to the previous block by using its hash values. That’s the reason behind the name blockchain. The SHA-256 algorithm makes the blockchain ledger transparent so that all users can verify it anytime.
Moreover, SHA-256 makes the blockchain secure and free from attacks. For instance, a miner should add a random string of numbers called the nonce to the content from the previous block and process it through the SHA-256 algorithm. Thus, no one can guess the correct string of numbers to retrieve content. It needs significant computational energy to guess the correct hash values, which is impracticable, making the network secure.
The SSL (Secure Socket Layer) handshake is crucial to web browsing sessions as it establishes a secure connection between the web browser and a server. The SSL handshake depends on the SHA-256 algorithm to connect securely between the browser and the server.
For instance, communication between server and browser always begins with an SSL handshake, which is asymmetric cryptography that enables the browser to verify the web server, get the public key, and set up a secure connection before data transfer.
SHA-256 verifies the data integrity of any files on the internet, like documents, videos, and software executables, during downloads and transfers. For instance, when a file is uploaded on the website, the algorithm generates a hash value for that file. Thus, when someone downloads the file, the hash value is computed again to maintain the data integrity. The file is verified only when both the hash values match.
Many top cryptocurrencies follow the SHA-256 algorithm, including Bitcoin. Here is the list of top mineable coins that follow the SHA-256 hash algorithm.
CONCLUSION
The SHA-256 algorithm plays a crucial role in many industries, especially cybersecurity and blockchain technology. It aids secure data transmission, digital signatures, and the mining process in various cryptocurrencies. Staying updated about the current technologies and trends and their use cases will help us stay ahead in the digital landscape. If you’re into crypto mining, here are some SHA-256 ASIC miners for you to explore.
Yes, SHA-256 is considered secure. When two different inputs generate the same hash output, a collision occurs. SHA-256 is known for its collision resistance and minimizes such collisions.
No. It is computationally infeasible to reverse the process and obtain the original input from the hash output. That, in turn, enhances the security of digital signatures and password storage.