Hashing from A to Z

Safeguarding your data and personal information has never been more important than today and hashing is a widely used method that acts as a guardian for our passwords and other types of sensitive information.

Hashing is a crucial element in modern cybersecurity, quietly safeguarding sensitive data and ensuring the integrity of digital information. At its core, hashing is a process that takes an input, referred to as a ‘key,’ and transforms it into a fixed-length string of characters known as a ”hash.” What makes hashing indispensable is its ability to provide a unique digital signature for data, allowing any alterations to be quickly detected.

The fundamental concept behind hashing revolves around the use of a mathematical algorithm called a hash function. This algorithm is designed to meet specific criteria: it must produce a consistent output length, be deterministic, efficient, exhibit the avalanche effect, and possess preimage resistance. These criteria ensure the reliability and security of the hash.

Let us go through why is hashing so important in today’s cybersecurity and how it is implemented in various fields.

What is hashing?

Hashing is a process that takes an input, often referred to as a ‘key,’ and transforms it into a fixed-length string of characters, known as a ”hash”. This hash is typically much shorter than the original input. The core components of hashing include:

1. Hash function: At the heart of hashing is the hash function, which is an algorithm responsible for performing the transformation. A good hash function should meet specific criteria:
   • It should take an input of any size and produce a fixed-length output (e.g., 256 bits).
   • It should be deterministic, meaning the same input will always yield the same hash.
   • It should be quick to compute.
2. Uniqueness: Ideally, different inputs should produce unique hashes. While it’s theoretically possible for two different inputs to yield the same hash (a collision), modern hash functions are designed to minimize this occurrence
3. Irreversibility: Hashing is a one-way process, meaning you cannot reverse a hash to retrieve the original input. This property is particularly valuable for securely storing passwords. Even if someone obtains the hash, they cannot determine the actual password from it

The concept of hashing has a rich history that predates the modern cryptographic applications we see today. Its origins can be traced back to ancient civilizations and early computer science developments.

Hashing, in a rudimentary form, was employed in ancient cryptographic techniques. For example, the Caesar cipher used a simple form of hashing by shifting characters in a message by a fixed number of positions. This transformation was a basic form of encoding, making it an early precursor to modern hashing.

In the early days of computer science, hashing was used primarily for data storage and retrieval. Hash tables, which are data structures that use hashing for efficient data access, became a fundamental concept. Algorithms like the division-remainder method and multiplication method were early approaches to hash functions.

As computers advanced, so did the need for secure data storage and transmission. Cryptographers recognized the value of hashing in protecting sensitive information. One significant milestone was the development of the Data Encryption Standard (DES) in the 1970s, which used hashing techniques as part of the encryption process.

Be safe inside your cyber fortress

The 1980s saw the emergence of modern cryptographic hash functions. The MD5 (Message Digest Algorithm 5) was one of the earliest widely used hash functions. However, as computing power increased, vulnerabilities in MD5 became apparent, leading to its gradual replacement by more secure algorithms like SHA-1 and eventually SHA-256.

Hash functions gained significant attention in the field of cryptography due to their role in creating digital signatures, secure data storage, and password protection. They became a cornerstone of modern digital security protocols and blockchain technology.

The introduction of Bitcoin and blockchain technology in 2009 brought hashing into the spotlight. Hash functions are essential to the security and integrity of blockchain networks, ensuring the immutability of transaction records.

Today, hashing has evolved into a fundamental concept in computer science and cryptography, playing a crucial role in securing data, verifying the integrity of information, and enabling innovations like blockchain technology. Hashing’s ability to transform data into a unique, fixed-length representation makes it indispensable for a wide range of applications, from efficient data retrieval to robust data security.

How does hashing work?

Hashing involves the transformation of an input (often referred to as a “key” or “message”) into a fixed-length string of characters, known as a hash value or hash code. Hashing serves various purposes, including data retrieval, data integrity verification, and password storage.

At the heart of hashing lies the essential element known as the hash function. This mathematical algorithm is meticulously crafted to accept input data of varying sizes and, in response, generate a standardized output of fixed length, often represented as a sequence of bytes or characters. A well-designed hash function adheres to specific criteria that underpin its reliability.

A good hash function meets specific criteria:

• Deterministic: For the same input, it will always produce the same hash value
• Quick to compute: The hash function should be computationally efficient to generate the hash quickly
• Avalanche effect: A small change in the input should result in a significantly different hash value
• Preimage resistance: It should be computationally infeasible to reverse the hash to retrieve the original input. This property ensures that the hash is irreversible

Firstly, it is deterministic, ensuring that for a given input, the resultant hash value remains constant.

Secondly, efficiency is a key attribute, demanding that the hash function performs its calculations swiftly and efficiently.

The avalanche effect, another critical aspect, guarantees that even the smallest alteration in the input leads to a vastly different hash value.

Lastly, preimage resistance is integral, rendering it computationally infeasible to reverse-engineer the hash to retrieve the original input, thereby safeguarding its irreversibility.

Hashing process

When data undergoes hashing, the initial input, whether it be a password, message, or file, is fed into the chosen hash function. This hash function subsequently engages in a series of mathematical operations, including bitwise manipulations, modular arithmetic, and logical functions, applied to the input. These operations collectively transform the input into a consistent-length output, effectively creating the hash value.

Fixed-length output

Hash functions consistently yield hash values of a predefined length, a property that remains invariant regardless of the size or length of the original input. Common hash lengths include 128 bits, 256 bits, 384 bits, and 512 bits, with the selected hash function, such as SHA-256, specifying the output size.

Uniqueness and collisions

Although hash functions are meticulously designed to produce unique hash values for distinct inputs, the theoretical possibility of two different inputs generating identical hash values, known as a collision, exists. To mitigate this risk, modern hash functions are rigorously engineered and subjected to extensive testing to minimize the probability of collisions.

What are the different types of secure hash algorithms?

There are several types of Secure Hash Algorithms (SHA). Here’s a brief explanation of some of the most commonly used SHA algorithms:

• SHA-1
• SHA-256
• SHA-224
• SHA-384 and SHA-512
• SHA-3 (Keccak)
• SHA-512/224 and SHA-512/256
• SHA-3-224 and SHA-3-256
• SHA-3 Shake

SHA-1

SHA-1 once held a prominent position. However, its widespread usage has waned due to identified vulnerabilities that render it susceptible to collision attacks. These attacks involve the discovery of two distinct inputs that yield the same hash value.

Consequently, SHA-1 is now considered deprecated for most cryptographic purposes, and experts recommend transitioning to more robust hash functions, such as SHA-256, to enhance data security.

SHA-256

SHA-256 stands as one of the prominent members of the Secure Hash Algorithm (SHA) family, renowned for its robust cryptographic properties. It is a widely used hash function known for its ability to take an input of arbitrary size and generate a fixed-length hash value consisting of 256 bits, or 32 bytes.

SHA-256 adheres to the deterministic principle, meaning that for any given input, it consistently produces the same 256-bit hash value. This property is fundamental for data consistency and reliability.

Efficiency is a hallmark of SHA-256. The algorithm’s design ensures that it can compute the hash value swiftly and efficiently, making it suitable for various applications where performance matters.

SHA-256 also exhibits the avalanche effect, meaning that even the slightest modification in the input data results in a substantially different hash value. This property enhances security by making it computationally infeasible for attackers to deduce the original input from the hash.

We should also mention that SHA-256 is preimage resistant, which means that it is exceedingly difficult, if not practically impossible, to reverse-engineer the hash value to retrieve the original input. This property makes it suitable for securely storing sensitive data like passwords.

SHA-224

An offshoot of SHA-256, SHA-224 is characterized by its production of a shorter 224-bit hash value. While it maintains a level of security akin to SHA-256, its advantage lies in its smaller output size. This makes SHA-224 an appealing choice in scenarios where a compact hash is preferred.

SHA-384 and SHA-512

SHA-384 and SHA-512 hash functions are part of the SHA-2 family, sharing lineage with SHA-256. What sets them apart is their capacity to generate longer hash values, with SHA-384 producing 384 bits and SHA-512 yielding 512 bits.

These extended hash lengths enhance security and are commonly deployed in contexts necessitating heightened data protection, such as digital signatures and certificate management.

SHA-3 (Keccak)

SHA-3 represents the latest addition to the Secure Hash Algorithm family. Born out of a public competition, SHA-3 is founded on the Keccak algorithm. What distinguishes SHA-3 from its predecessors in the SHA-2 family is its distinct internal structure, which translates into a robust level of security. SHA-3 offers versatility with various bit lengths, including SHA3-224, SHA3-256, SHA3-384, and SHA3-512.

SHA-512/224 and SHA-512/256

Designed for scenarios necessitating a balance between security and efficiency, these are truncated versions of SHA-512. They yield shorter hash values, providing practical solutions for specific applications.

SHA-3-224 and SHA-3-256

As variants of SHA-3, these hash functions generate shorter hash values and are well-suited for diverse applications where SHA-3’s distinctive properties are advantageous.

SHA-3 Shake

A notable feature of SHA-3 is its SHAKE mode, enabling variable-length output. This flexibility empowers SHAKE to produce hashes of varying lengths, rendering it adaptable for a wide array of cryptographic applications.

Each of these SHA algorithms serves a specific purpose within cryptography systems, offering varying levels of security and efficiency to cater to the unique demands of different applications and security requirements.

The elephant in the room

Hashing plays a crucial role in maintaining the integrity of data. When data is hashed, it results in a unique hash value that acts like a digital fingerprint for that specific data. Any alteration, no matter how minor, in the original data should lead to a completely different hash value due to the avalanche effect.

Collisions in hashing, however, defy this fundamental property. When two different inputs produce the same hash value, it becomes impossible to reliably distinguish between them based solely on their hash values. This poses a clear threat to data integrity checks, as changes to the data may go unnoticed.

Before storing user passwords in a database, they are hashed. During the login process, the entered password is hashed and compared to the stored hash. Collisions can be particularly problematic here. If two different passwords generate the same hash, an attacker could potentially use one password to gain unauthorized access, thereby posing a direct threat to password security.

Hash functions are also the foundation of digital signatures, serving to confirm the authenticity and integrity of digital documents and transactions. In the context of cryptographic signatures, collisions in hashing can enable attackers to craft two distinct documents with identical hash values. This can cast doubt on the reliability of digital signatures and create concerns regarding the validity of digital documents.

Also, as exemplified by cryptocurrencies like Bitcoin, hash functions are employed to secure transactions and blocks. The occurrence of collisions can introduce vulnerabilities, potentially allowing attackers to manipulate transaction records or compromise the overall security of the blockchain, which can, in turn, affect the trustworthiness of digital currencies.

So how do you prevent collisions in hashing? Salting is the right card to play here.

What is salting and how does it help hashing?

Salting is the process of adding random data, known as a salt, to the input data before it is hashed. This salt is typically a random string of characters. The primary purpose of salting is to enhance the security of hashed data, especially when it comes to protecting passwords.

When a salt is introduced into the hashing process, it brings about several crucial advantages.

One of the fundamental benefits of salting is the generation of unique hashes, even for users with identical passwords. When a salt is combined with the password or passphrase before hashing, it ensures that each user’s hash is distinct, even if they share the same password. This uniqueness thwarts attackers who attempt to identify common passwords by comparing hash values, as identical passwords yield different hashes due to the unique salts.

Salting also serves as a powerful defense mechanism against attacks involving precomputed tables, such as rainbow tables. These tables store precomputed hashes of common passwords, allowing attackers to quickly match hashes to passwords. However, when salts are employed, each salted password produces a unique hash, rendering precomputed tables ineffective and significantly increasing the computational effort required for attacks.

Furthermore, salting addresses the security concern of protecting passwords that occur multiple times in a database. With the use of a unique salt for each password instance, even if users share the same password, their hashed values will be distinct. This ensures that the compromise of one password does not jeopardize the security of others.

Crucially, salting does not impose any burdens on users; it is a transparent process that occurs behind the scenes.

The salting process typically involves the following steps:

1. A random salt is generated for each password
2. The salt is concatenated with the password (or its modified form after key stretching)
3. The combined data is fed into a cryptographic hash function
4. The resulting hash value is stored in a database alongside the corresponding salt
5. Importantly, the salt itself does not need to be encrypted, as its knowledge alone does not assist attackers in compromising the hashed data

Salting is widely employed in cybersecurity, extending its application from Unix system credentials to Internet security protocols. It enhances data privacy and security in various scenarios, ensuring that hashed data remains resistant to common attack techniques.

All too confusing? Here is a table demonstrating how salting helps with hashing:

In this example:

• Each user is assigned a unique salt value
• The password for each user is combined with their respective salt value
• The combined data (password + salt) is then hashed using the SHA-256 hashing algorithm
• The resulting hashed value is stored in the database alongside the salt value

This process ensures that even if users have the same password, their hashes will be different due to the unique salt values, thereby enhancing security and preventing attackers from easily identifying identical passwords by comparing hash values.

The perfect privacy cloak for sensitive information

Hashing finds applications across various industries and businesses for data management, security, and optimization. Here are some common applications of hashing in different business domains:

Cybersecurity and data protection

• Password storage: Hashing is used to securely store user passwords in databases. Hashed passwords are challenging to reverse-engineer, adding a layer of security in case of data breaches
• Access control: Hashes can be used in access control systems to verify the authenticity of user credentials, ensuring that only authorized personnel gain access to sensitive data or areas
• Digital signatures: Hashing is fundamental to digital signatures, ensuring the integrity and authenticity of digital documents, contracts, and transactions

Finance and banking

• Data integrity: Hashing is employed to verify the integrity of financial data during transactions, preventing unauthorized alterations
• Cryptocurrency: In blockchain technology, hashing is used to secure transactions and create blocks, underpinning cryptocurrencies like Bitcoin

E-commerce

• Data retrieval: Hash tables are used to optimize the retrieval of product information, ensuring quick access to product details based on unique identifiers
• User authentication: Hashing is employed to secure user authentication processes, enhancing the security of customer accounts

Healthcare

• Patient data security: Hashing protects sensitive patient information, such as medical records and personal data, ensuring confidentiality and integrity
• Drug authentication: Hashing is used to verify the authenticity of pharmaceutical products, safeguarding against counterfeit drugs

Supply chain and logistics

• Inventory management: Hashing facilitates efficient tracking and management of inventory by optimizing data retrieval and minimizing search times
• Tamper detection: Hashes are used to detect unauthorized alterations or tampering of supply chain data, ensuring the authenticity of products in transit

Online advertising and marketing

• Ad targeting: Hashing is used to match user profiles with relevant advertisements while preserving user privacy through techniques like hashed email matching
• Data analytics: Hashing aids in data aggregation and anonymization, enabling businesses to analyze consumer behavior without exposing individual identities

Telecommunications

• Data deduplication: Hashing is used to eliminate duplicate data in large datasets, optimizing storage and reducing data transfer times
• Network security: Hashing is applied to secure communication protocols and authenticate devices in telecommunications networks

Manufacturing and quality control

• Product traceability: Hashing is used to track the production history and quality control of manufactured products, ensuring consistency and accountability
• Parts authentication: Hashing is employed to verify the authenticity of critical components and prevent the use of counterfeit parts

Legal and intellectual property

• Document timestamping: Hashing can be used to timestamp legal documents, ensuring the authenticity and integrity of contracts and agreements
• Intellectual property protection: Hashing can protect digital intellectual property, such as copyrighted content or software, from unauthorized distribution

Education and e-Learning

• User authentication: Hashing enhances the security of user accounts and authentication in e-learning platforms
• Content verification: Hashes can verify the integrity of educational materials, ensuring that they have not been altered or tampered with

These are just a few examples of how hashing is applied across different business sectors to enhance security, optimize data management, and ensure the integrity of critical information. Its versatility and effectiveness make hashing a valuable tool in a wide range of industries.

Hashing’s importance in cybersecurity cannot be overstated. It forms the bedrock of data security, providing an unyielding shield against unauthorized access and tampering. In the digital age, where data protection is paramount, hashing stands as a silent sentinel, ensuring the sanctity of our digital information.

Featured image credit: rawpixel.com/Freepik.