Encryption and hashing are at the heart of several new types of security modules that have been developed for networks. One of the most used hash algorithms is the Secure Hash Algorithm with a 256-bit Digest Size (SHA 256). Even if there are other versions, SHA 256 has seen the most widespread use in practical settings so far.
Understanding hashing and its functional properties is a prerequisite to comprehending the SHA 256 algorithm’s operation.
What is Hashing?
Hashing is the technique of encoding data in such a way that its original form cannot be restored. It takes in some data and sends it on to another function, which does some kind of mathematical operation on the plaintext. The name for this operation and its result, the hash value or digest, is “hash function” and “hash value” respectively.
The following illustration shows how the hash function transforms the plaintext into the corresponding hash digest. They are intended to be permanent, thus your digest shouldn’t let you back into the original plaintext. If the input does not change, then the hash function will always provide the same result.
Applications of hashing may be broken down into two categories:
Passwords Hashes: Passwords to websites are often hashed before being saved on the server. At login, it recalculates a hash value and checks it against the one saved in the database.
Integrity Checking: The file’s hash is sent with the uploaded file whenever it’s uploaded to a server. The hash may be recalculated and compared to the original upon download, guaranteeing the file’s authenticity.
Now that you know how hash functions operate, let’s examine the key issue at hand: the SHA 256 algorithm.
What the SHA-256 Algorithm?
The Secure Hash Algorithm (SHA) 2 family includes SHA 256 as one of its algorithms. An NSA/NIST collaboration published in 2001, it introduced a new hashing algorithm to replace the SHA 1 family, which was becoming more vulnerable to brute-force assaults.
The 256 in the name refers to the length of the resulting hash digest, which is fixed at 256 bits regardless of the length of the plaintext or cleartext being hashed.
As a general rule, the other algorithms in the SHA family behave similarly to SHA 256. The next step is to learn more about their regulations.
What are the Characteristics of the SHA-256 Algorithm?
The following is a list of some of the most notable characteristics of the SHA algorithm:
Message Length: The length of the cleartext should be fewer than 264 bits. This metric is measured in bits. In order to maintain the maximum degree of randomness in the digest, the size must fall inside the comparison region.
Digest Length: The length of the hash digest must be 256 bits when using the SHA-256 algorithm, 512 bits when using the SHA-512 algorithm, and so on. Greater digest sizes almost often imply much more computations, which comes at the expense of both time and space.
Irreversible: All hash functions, including the SHA 256, are designed to be irreversible by their very nature. You shouldn’t be able to recover the original value of the digest if you run it through the hash function again, and you also shouldn’t be able to recover the plaintext if you already know the digest.
The following part will walk you through the SHA method in its entirety, which you may do now that you have a general understanding of the technical prerequisites for SHA.
Steps in SHA-256 Algorithm
There are five distinct parts that may be extracted from the whole procedure, and they are as follows:
Padding Bits
The message receives some more bits as a result, bringing the total number of bits to precisely 64 bits shy of a multiple of 512. During the process of addition, the first bit has to be set to one, and the other bits need to be filled with zeroes.
Padding Length
You may add another 64 bits of data at this time to make sure that the plaintext that is output is a multiple of 512. You can figure out these 64 bits of character by using the modulus to your initial cleartext without the padding and then doing a little of math.
The following are the default settings for eight buffers that will be utilized in the iterations:
Additionally, you’ll need to keep track of 64 distinct keys in an array, labeled K[0] through K[63]. This is how they are set up to begin with:
Courtesy: SHA-2 (Wikipedia)
Compression Functions
The whole message is divided up into 512-bit chunks. Each block is operated on 64 times, with the results feeding into the next block as input. All that has to be done is as follows::
Courtesy: Medium Article on SHA 256
While K[i] is a constant across all these iterations, W[i] is an input that must be determined uniquely for each block based on the current iteration count.
Output
The result of one block is used as the input for the next block in an iterative process. After reaching the last 512-bit block, the process starts over again, and the result is used as the final hash digest. By definition, this algorithm’s name implies that the digest it produces will be 256 bits long.
Since the SHA 256 algorithm has been widely used since the early 1990s, you may research it in a variety of contexts. They’ll be shown to you in the next chapter.
Applications of SHA algorithm
As can be seen in the graphic that is shown above, the SHA algorithm is used in a variety of settings, some of which include the following:
Digital Signature Verification
In order to validate the originality of a document or file, digital signatures use a kind of encryption known as asymmetric encryption. The use of hashing techniques such as SHA 256 is an important step in guaranteeing that the signature can be verified.
Hashing Your Password
As was just reviewed, websites save the passwords of their users in a format called hashed for two reasons. It contributes to the development of a feeling of anonymity, and the fact that all of the digests of the same size helps to reduce the strain placed on the central database.
SSL Handshake
The SSL handshake is an essential part of the sessions used to browse the web, and it is accomplished with the help of SHA functions. In order to set up a secure connection, your online browser and the web servers you access to must first reach an agreement on the encryption keys and hashing authentication to use.
Verifications of the Integrity
In the last section, we went over how the SHA 256 method and the MD5 algorithm are both used in the process of confirming the file’s integrity. It ensures that the files have not been changed in any way while they were being transferred, which helps to keep the files’ full functioning intact.
Conclusion
Hashing, its uses, the history of Secure Hash Algorithm (SHA), how it operates, and its practical applications are all covered in today’s SHA 256 tutorial.