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The Fundamentals of SHA-256
The Practices of SHA-256
The Pros and Cons of SHA-256

1.0 The Fundamentals of SHA-256

SHA-256 is a cryptographic hash function that is widely used in various applications, such as digital signatures, encryption, authentication, and blockchain. SHA-256 stands for Secure Hash Algorithm 256, which means it produces a fixed-length output of 256 bits (32 bytes) from any input, regardless of its size or content. SHA-256 is designed to be one-way, meaning that it is easy to compute the output from the input, but hard to find the input from the output. SHA-256 is also collision-resistant, meaning that it is very unlikely that two different inputs will produce the same output.
SHA-256 was developed by the US National Security Agency (NSA) and published in 2001 as a standard by the National Institute of Standards and Technology (NIST). It is part of the SHA-2 family of hash functions, which also includes SHA-224, SHA-384, SHA-512, SHA-512/224, and SHA-512/256. SHA-2 is an improvement over the previous SHA-1 and SHA-0 hash functions, which have been shown to be vulnerable to attacks.
SHA-256 can be implemented in various ways, such as software, hardware, or a combination of both. One way to implement SHA-256 in hardware is to use a chip or an integrated circuit that contains all the necessary components and logic to perform the hash function. A chip can offer advantages such as speed, efficiency, security, and portability over software implementations. However, a chip also has limitations such as cost, complexity, and compatibility.
One example of a chip that implements SHA-256 is the gadget interface chip. A gadget interface chip is a device that connects to a USB port and provides a simple interface for performing cryptographic operations. A gadget interface chip can be used to generate or verify digital signatures, encrypt or decrypt data, or create or validate hashes. A gadget interface chip can also be programmed to support different hash functions, such as SHA-1, SHA-2, or SHA-3.
A gadget interface chip consists of three main components: a microcontroller, a memory, and a cryptographic engine. The microcontroller is the brain of the chip that controls the communication with the host computer and executes the instructions for the cryptographic operations. The memory is where the data and the keys are stored and accessed by the microcontroller and the cryptographic engine. The cryptographic engine is where the actual hash function is performed. The cryptographic engine can be either a dedicated hardware module or a software module running on the microcontroller.

1.1 The basic steps for performing SHA-256 on a gadget interface chip are as follows:

  1. The host computer sends a command to the chip with the data to be hashed and optionally a key.
  2. The chip receives the command and stores the data and the key in its memory.
  3. The chip invokes its cryptographic engine to compute the hash of the data using SHA-256 and optionally using the key.
  4. The chip returns the hash value to the host computer.
    The following diagram illustrates these steps:

The host computer sends a command to the chip with the data to be hashed and optionally a key. The chip receives the command and stores the data and the key in its memory. The chip invokes its own cryptographic engine to compute the hash of the data using SHA-256 and optionally using the key. The chip returns the hash value to the host computer.

1.2 SHA-256 has many advantages and disadvantages as a hash function.


  • It provides strong security against brute-force attacks, as it would take an enormous amount of time and resources to find an input that produces a given output.
  • It provides strong security against collision attacks, as it would take an astronomical amount of time and resources to find two inputs that produce the same output.
  • It is widely adopted and supported by various standards, protocols, platforms, and applications.
  • It is relatively simple and efficient to implement in software or hardware.


  • It has a large output size compared to other hash functions, which may increase the storage and transmission costs.
  • It has a relatively slow performance compared to other hash functions, especially on low-power devices or platforms.
  • It may be vulnerable to future attacks or weaknesses that are not yet discovered or disclosed.
  • It may be subject to legal or regulatory restrictions or requirements in some countries or regions.

SHA-256 is a powerful and versatile hash function that can be used for various purposes and applications. However, it also has some limitations and challenges that need to be considered and addressed. Therefore, it is important to understand how SHA-256 works and what are its pros and cons before using it.
The Practices of SHA-256
Features of the SHA 256 Algorithm
The SHA-256 algorithm is a robust cryptographic tool, boasting features ensuring data security and integrity. Here are some key features that define SHA-256 encryption:-
Cryptographic Hash Function: SHA-256 is a cryptographic hash function that takes an input (message) and produces a fixed-size output (hash value). This output is unique to each unique input and appears random, making it extremely difficult to reverse-engineer the original message from the hash value.

Fixed Output Length: SHA-256 generates a hash value of 256 bits (32 bytes) in length. This consistent output allows for efficient data comparison and integrity verification.
Collision Resistance: SHA-256 exhibits high collision resistance, meaning it is statistically improbable for two different inputs to produce the same hash value. This property ensures that even a slight change in the input results in a substantially different hash value.
Avalanche Effect: The smallest change in the input data leads to significant changes in the hash value, creating a domino effect throughout the output. This avalanche effect ensures that even minor modifications in the input yield vastly different hash results.
One-Way Function: SHA 256 is designed to be a one-way function, making it computationally infeasible to reverse the hashing process and deduce the original input from the hash value. This property contributes to its use in password storage and digital signatures.
Deterministic: Given the same input, the SHA 256 algorithm will always produce the same hash value. This predictability allows for consistent verification and authentication processes.
Efficiency: SHA 256 strikes a balance between security and efficiency. It offers a high level of security while being relatively fast in computation, making it suitable for a wide range of applications.
Wide Applicability: SHA 256 is widely adopted across various domains, including digital signatures, password storage, blockchain technology, and data integrity verification.
Standardization: SHA 256 is a NIST-approved standard, ensuring its implementation and security characteristics have undergone rigorous scrutiny and evaluation.
Resistance to Preimage Attacks: The SHA 256 algorithm resists preimage attacks, making deducing an input corresponding to a specific hash value challenging.
SHA 256 has proved its prowess in safeguarding various aspects of our digital lives. Let’s explore the diverse applications of the SHA 256 algorithm:-
Protecting the Data Integrity
SHA 256 serves as a vigilant guardian of data integrity. It transforms data into a fixed-size hash value, ensuring that even the slightest modification in the input results in a vastly different output. By comparing the hash values of original and received data, discrepancies can be swiftly detected, making it a crucial tool in maintaining the accuracy and trustworthiness of digital information.
Verifying Digital Signatures
Digital signatures provide authenticity to digital documents and communications. SHA 256 plays a vital role by creating a hash value of the content to be signed. This hash value is then encrypted using a private key, forming the digital signature. Recipients can use the corresponding public key to decrypt and verify the signature, ensuring the sender’s identity and document integrity.
Password Hashing
Storing passwords in their raw form is risky. SHA 256 and salt (a random value) are employed to securely hash passwords before storing them. When users log in, their entered password is hashed and compared to the stored hash, verifying authenticity without revealing the actual password. This shields sensitive information from potential breaches.
Verifying Blockchain Transactions
In blockchain, where transparency and security are paramount, SHA 256 stands as a cornerstone. It’s used in the proof-of-work mechanism to verify and link transactions into blocks. Each new block’s hash contains the previous block’s hash, creating an immutable chain. The SHA-256 algorithm ensures the consistency and integrity of the entire blockchain network

The Pros and Cons of SHA-256
Pros of SHA-256:
Security: SHA-256 is considered highly secure due to its resistance to collision attacks. A collision occurs when two different inputs produce the same hash value. While it’s theoretically possible, it’s computationally infeasible to find such collisions for SHA-256.

Speed: SHA-256 is relatively fast in computation, making it efficient for many cryptographic applications, such as digital signatures and data integrity checks.
Deterministic: Given the same input, SHA-256 will always produce the same output hash value, ensuring consistency in cryptographic operations.
Widely Adopted: SHA-256 is widely used and supported across various programming languages, libraries, and platforms, making it accessible for developers.
Blockchain Technology: SHA-256 plays a critical role in blockchain technology, serving as the basis for proof-of-work (PoW) algorithms in cryptocurrencies like Bitcoin.
Cons of SHA-256:
No Longer “Quantum-Safe”: With the advent of quantum computing, SHA-256’s security is potentially at risk. Quantum computers could potentially break SHA-256 through Grover’s algorithm, which would make it less secure in a post-quantum world.

Deterministic: While determinism is a pro for security, it can be a con for privacy. Given the same input, SHA-256 will always produce the same hash, which can potentially leak information about the input data.
Not Suitable for Password Storage: SHA-256 is not suitable for securely storing passwords. It lacks the necessary features like salting and stretching, which are essential for password security.

Resource Intensive: While it’s fast, SHA-256 can still be resource-intensive for large-scale applications or devices with limited computational power.
Size of Hash Value: SHA-256 produces a fixed-size output of 256 bits, which can be larger than necessary for some applications, leading to wasted storage space.

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