What Is Hashing? Cybersecurity Hashes Explained

For websites, security is crucial when it comes to dealing with user data. Most website owners choose to use cryptography hashing to keep login credentials safe. The hash function takes input data of any size, like your password or a user file, and converts it into a fixed-length "hash value" that can't be reversed. Though hashing may seem complex, it's a key concept worth understanding. In this article, get the answer to the question "what is hashing?" to learn how it works and why many choose to use it.

What is hashing?

Hashing is becoming more and more common as a cybersecurity technique, but what is hashing? Hashing is the process of altering pieces of data or information into a fixed length that can't be recognized. As a cryptographic technique, users utilize it to protect data and improve security on messages that need to reach their destination safely.

The technique works by converting inputted data of any length into a fixed-size string of text using mathematical functions. Therefore, this means that any text, no matter how long, can change into an array of numbers and letters through an algorithm.

The cryptographic hash function takes the input data and produces a new value according to a mathematical algorithm. The same input will always produce the same output, but a small change in the input will result in a completely different output.

Though many people use the terms 'hashing' and 'encryption' interchangeably, hashing is a one-way function. This prevents the conversion of the hash back into the original key, which is necessary because that would defeat the purpose of hashing as a security measure. Because hashes are a one-way functionality, hash values are extremely difficult to decode and extremely secure.

What is a hash?

A hash is a fixed-size string of characters or a numerical value generated by a hash function. It's simply the output of the hash function; the input passes through a hash function to calculate a hash value or hash.

Components of hashing

There are four important terms to know when it comes to understanding hashes:

• Input. Input refers to the initial data that you want to hash. The input is actually manipulated and transformed into the hash value.
• Hash function. The hash function refers to the mathematical algorithm that converts the input into hash values. The hash function scrambles and condenses the input to create a fixed-length hash value.
• Hash value or digest. The hash value refers to the output of the hash function; it presents as a string of letters and numbers of a fixed length that represent the input. The hash value essentially operates as a digital fingerprint for the input.
• Salt. Salt refers to a random string of data added to the input before hashing that makes the hash more difficult to crack. Even if two inputs are the same, their salt will be different, resulting in differing hash values.

Hashing plays an important role in security and cryptography. Understanding these basic components - the input, the hash function, the hash value, and the salt - will help you understand how hashing works.

How hashing works

Hashing in cybersecurity works by transforming data into fixed-length outputs called hashes. These hashes serve as unique identifiers for the data. The process involves passing data through a hashing algorithm, which then uses a hash function to map the data into a seemingly random string of characters. The end result is a hash value.

Even though the hashing process generates a random-looking output, it will always produce the same hash value for the same input data.

Properties of hash functions

There are a number of different approaches hashing functions use to convert data into hash values, but a good hash function in cryptography should have the following properties:

• Uniformity. A hash function aims to distribute hash values uniformly across its output space. This minimizes the likelihood of collisions, where different inputs produce the same hash value.
• Irreversibility. A good hashing algorithm should be impossible to reverse engineer. Because only the recipient should interpret the data, this one-way property makes hashing suitable for password storage and other functions that require obscured data.
• Quick computation. Hashing algorithms need to compute efficiently, even with large inputs. This allows hashing to work in tasks where speed is critical, like digital signatures.
• Consistency. Hashing algorithms should always produce the same hash value for a given input. This deterministic property makes hashing useful for lookup tables and database indexing.
• Sensitivity to input changes. Even a small change in the input data should produce a significantly different hash value. This property is crucial for verifying data integrity and detecting any modifications.

What is hashing used for?

Common hashing algorithms

Since the early days of cyber security, researchers have developed various hashing algorithms, each with their own methods. The most popular cryptography hashing algorithms used today include:

Message Digest 5 (MD5)

The MD5 algorithm is a widely used hash function that produces a 128-bit hash value. It verifies data integrity, like making sure a file you download remains unchanged from its original version.

The MD5 hash expresses as a 32-character hexadecimal number, like d41d8cd98f00b204e9800998ecf8427e. Because the hash output is unique, any change to the input data will result in a different MD5 hash.

Secure Hash Algorithm 1 (SHA-1)

SHA-1 is another popular hashing algorithm that generates a 160-bit hash value. The NSA (National Security Agency) developed it as a successor to MD5. The increased hash length makes it less prone to collisions where two different inputs generate the same hash.

This algorithm is expressed as a 40-character hexadecimal number. We use SHA-1 to verify file integrity and digital signatures.

Secure Hash Algorithm 2 (SHA-2)

SHA-2 refers to a family of hash functions - SHA-224, SHA-256, SHA-384, and SHA-512 - with hash lengths of 224, 256, 384, and 512 bits, respectively. SHA-256 generates a 64-bit hash and is frequently used for blockchain applications.

The longer hash lengths of SHA-2 make it even more resistant to collisions than MD5 and SHA-1.

BLAKE2

BLAKE2 is a newer hash function optimized for speed. It comes in versions with hash lengths of 256 as well as 512 bits. BLAKE2 provides stronger security as well. Its performance is faster than that of MD5, SHA-1, and SHA-2.

Currently, the algorithm is starting to be adopted for blockchain projects and as a general-purpose hashing algorithm. The BLAKE2b-512 hash is 128 characters long.

CRC32

While one purpose of hashing is to detect changes and errors in data, most people work with CRC32. The cyclic redundancy check (CRC) code offers a quick way to check file integrity, especially with files downloaded from FTP (File Transfer Protocol) servers.

What are hash tables?

A hash table is a data structure that stores key-value pairs in an associative manner. In hashing, input data is converted into new values through the use of hash functions. The values are then stored in a hash table.

In a hash table, the hash function generates an index or a hash code. This code is then used to determine the location where the corresponding value will be stored.

The idea is to distribute the keys uniformly across the array to minimize collisions. The key characteristics of a hash table include:

• Fast retrieval. Hash tables provide constant-time O(1) for insertions, deletions, and searches, making them highly efficient for accessing data.
• Key-value pairs. Each entry in a hash table consists of a key and its associated value. The value can be any data, while the key serves as a unique identifier.
• Collision resolution. Since different keys can map to the same hash code, hash tables employ techniques to handle such cases. Common collision resolution methods include chaining or open addressing.
• Scalability. The tables dynamically resize themselves to accommodate more elements as needed. This ability therefore allows them to handle large amounts of data efficiently.

Hash tables support functions that include the following:

• Search, which finds an element in the hash table
• Insert, which adds an element to the hash table
• Get, which searches a key inside the hash table
• Delete, which is responsible for deleting a particular key-value pair from the hash table
• Put, which inserts a new key-value pair inside the hash table

Hash tables may also support other operations, such as resize and collision resistance and resolution.

Limitations of hashing

Cryptography hashing isn't a perfect technology. Some issues may arise in the process. Consider the following limitations of hashing to make sure you prepare yourself for all of the possibilities when hashing.

• Hash collisions are unavoidable for a fixed hash table size.
• When hash values are not easily distributed in the hash table, they lead to overloaded clusters.
• If a hash function is not cryptographically secure, it may be possible to find inputs that yield the same hash value, resulting in collision.
• Hash tables can be complex to implement.
• Hash does not allow null values.
• Hash tables offer a limited capacity, so they will eventually fill up.

Comparing hashing and encryption

To store data, you have two options. You can either encrypt data using the encryption and decryption keys, or you can store data in a hash value. Both hashing and encryption protect your data, but they have significant differences, which are visible in their respective functionalities.

Assess the table below to gain a better understanding of the differences between hashing and cryptography.

	Encryption	Hashing
Primary function	Provides efficient protection facilities to ensure the confidentiality of data transmission	Helps in data verification and integrity
Process	Encryption is a two-way process	Hashing is a one-way function
Data	The message is encrypted and only authorized users can read it	Data is mapped to an output of fixed size
Length of output	Variable	Fixed
Reversible?	Yes, with the correct key	No

Frequently asked questions

What is a collision?

A collision is a situation where two or more keys generate an identical hash value. This is likely to occur, as hash functions are not perfect.

How is hashing used in databases?

In databases, cryptography hashing ensures data consistency. Therefore, by calculating hash values for records, it becomes possible to identify duplicate entries efficiently and easily. This boosts data accuracy as it reduces redundant data.

What are the types of hashing in data structure?

The main hashing types in data structure are chained hashing and open address hashing.

What does a hash value look like?

A hash value typically appears as a sequence of characters. This sequence can be of any length; it depends on the hashing algorithm used. The hash value of the string "hello world," for example, might be 2123456789abcdef at 16 characters long.