Cryptographics

Cryptographic algorithms are the basic building blocks of a secure system and protocols.

A security protocol is a set of measures to accomplish required security objectives by employing suitable security mechanisms. Security mechanisms are generally referred to as cryptographic functions, which have the fundamental property of representing the data in another form. Diverse kinds of security protocols are in practice, such as authentication, non-repudiation, and key management protocols. As one of the crypto-intensive technologies, Blockchain has become a scorching topic.

Many security and privacy issues have been addressed for Blockchain supported by cryptographic primitives. Basic cryptographic primitives include hash primitives, digital signature, and encryption primitives which are incorporated in Blockchain.

Introduction

Generally, the cryptographic primitives are essential in applications with an open nature, i.e., available to all for using and joining applications. These applications can easily be forged or targeted by malicious users or entities, making more robust secrity mechanisms.

Security mechanisms are generally referred to as cryptographic functions, which have the fundamental property of representing the data in another form. While transmitting the data or even in the store, the data cannot be easily understood or stolen by malicious entities or users. Basic cryptographic primitives include the hash functions, digital signature, implementation of hash pointers in various applications, hashchain mechanism, and many other concepts.

They are required in a computer security system to construct cryptographic protocols. The concepts mentioned above are applied to a specific application to gain the maximum security from malicious users or entities. These concepts are widely used in many different fields and widely accepted as concrete mechanisms for security and thus not easily be forged by malicious users. Blockchain is an open environment. The kind of application blockchain is open, distributed, and decentralized. In this case, the data can be transmitted from any node to another node in the system. We cannot track the data transmission until some transaction has been committed. So, we need to ensure that while transmitting the data, the data must be flowing securely. Thus, we apply some security measures to ensure the integrity of the data.

We apply cryptographic hash primitives here and other properties of the blockchain that cannot easily modify the blockchain’s block. This property strongly supports the hashchain mechanism, which is applied using a basic concept of hash pointers and hashing. Although it can apply these concepts in any application, the application’s kind of applicability and nature modify the basic structure of the basic cryptographic primitives and use it in a way that can be helpful in that particular application. In this chapter, we have presented some of the most used basic cryptographic primitives from the perspective of blockchain. Blockchain is considered the most full-proof, secure, and unmodifiable system for digital currency and other applications. The primary concept behind these properties is the application of the basic cryptographic hash primitives.

Core Cryptographic Concepts

Cryptography is the science of securing communication and data through the use of mathematical techniques. Core cryptographic concepts include:

Encryption and Decryption

• Encryption is the process of converting plaintext (readable data) into ciphertext (encoded data) to prevent unauthorized access.

• Decryption is the reverse process, converting ciphertext back into plaintext using a key.

Symmetric and Asymmetric Cryptography

• Symmetric Key Encryption uses the same key for both encryption and decryption. It is efficient and fast but requires secure key distribution. Examples: AES (Advanced Encryption Standard), DES (Data Encryption Standard), and 3DES.

• Asymmetric Key Encryption (or Public-Key Cryptography) uses a pair of keys: a public key for encryption and a private key for decryption. It provides secure key exchange and digital signatures. Examples: RSA, ECC (Elliptic Curve Cryptography), and DH (Diffie-Hellman).

Hash Functions Algorithms

• A hash function takes an input (or message) and returns a fixed-size string of bytes. The output, called the hash value, is typically a digest that uniquely represents the input data.

• Hash functions are designed to be fast, deterministic, and collision-resistant (i.e., different inputs should not produce the same output).

• Examples: SHA-256 (Secure Hash Algorithm), MD5 (Message Digest Algorithm 5).

Digital Signatures

• A digital signature is a mathematical scheme for verifying the authenticity and integrity of a message, software, or digital document.

• It uses a combination of hashing and asymmetric cryptography.

• The signer generates a signature using their private key, and the verifier uses the signer's public key to validate it.

• Examples: RSA signatures, ECDSA (Elliptic Curve Digital Signature Algorithm).

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