Checksum algorithms

A checksum is a value calculated from a data set to verify the integrity of the data. Checksum algorithms are mathematical functions that take an input (or message) and produce a fixed-size string of characters, which is typically a sequence of numbers or letters. This output, the checksum, can be used to detect errors or changes in the data that may occur during transmission or storage.

Cyclic Redundancy Check (CRC) is an error-detecting code used to detect accidental changes to raw data in digital networks and storage devices. It is a type of non-secure hash function that produces a checksum or "hash" value based on the contents of a data block. ### Key Features of CRC: 1. **Mathematical Basis**: CRC is based on polynomial long division.

The International Standard Book Number (ISBN) is a unique identifier for books, intended to simplify the distribution and purchase of books by providing a specific code for each title and edition. An ISBN is a 13-digit number (or 10 digits for editions that were published before 2007), which helps libraries, retailers, and consumers to distinguish between different books.

Adler-32 is a checksum algorithm created by Mark Adler, which is primarily used for data integrity verification. It is designed to be fast and efficient while generating a relatively small checksum for a given input of data. Adler-32 computes a checksum by combining the sum of the bytes of the input data into two separate values: `A` and `B`. The final checksum is formed by combining these two values into a 32-bit result.

BLAKE is a cryptographic hash function that was designed as part of the NIST hash function competition, which aimed to develop a new standard for secure hashing. BLAKE was one of the finalists in this competition, although it ultimately did not win. The function was proposed by Jean-Philippe Aumasson, Samuel Neves, Zooko Wilcox-O'Hearn, and Christian Rechberger.

The BSD checksum, also known as the Internet checksum or the RFC 1071 checksum, is a simple error-detection mechanism used primarily in networking protocols to verify the integrity of data. It is widely used in various BSD operating systems and protocols such as IP, TCP, and UDP. ### How it Works 1. **Data Segmentation**: The data to be checksummed is divided into words (typically 16 bits).

A checksum is a value used to verify the integrity of a data set. It is typically calculated by applying a specific algorithm to a block of data and producing a fixed-size string of characters, which can be in the form of a number or a sequence of hexadecimal digits. The primary purpose of a checksum is to detect errors that may have occurred during data transmission or storage.

Cksum, or "checksum," is a utility commonly used in computing and telecommunications to verify the integrity of data. A checksum is a value that is calculated from a data set (like a file or a block of memory) to help ensure that the data has not been altered or corrupted during transmission or storage. When data is transmitted or saved, a checksum is generated based on the contents of the data.

Fletcher's checksum is a type of error-detecting checksum algorithm that is designed to detect errors in data transmission or storage. It was developed by John G. Fletcher in 1982 and is commonly used in applications where performance and error detection capabilities are necessary. Fletcher's checksum is particularly known for its simplicity and efficiency.

ISO/IEC 7064 is an international standard that specifies methods for generating check digits for use in identification numbers. It is primarily focused on algorithms used to create check digits for numeric codes, which help in error detection. The standard provides mathematical methods to calculate check digits, which ensure that a given number, such as a product code, can be verified to be valid through the calculated check digit.

ISO 6346 is an international standard that specifies the identification and coding of containers used in intermodal freight transport. It provides a standardized method for identifying sea containers and is widely used in the shipping and logistics industries. Key components of ISO 6346 include: 1. **Container Identification**: The standard outlines a system for uniquely identifying containers through a combination of letters and numbers. Each container is assigned a unique owner code, a size/type code, and a check digit.

The ISSN, or International Standard Serial Number, is an eight-digit numeric code used to uniquely identify serial publications such as journals, magazines, newspapers, and other continuing resources. Each serial publication is assigned its own ISSN, which helps in cataloging and managing these resources in libraries, databases, and for publication management. The ISSN is usually presented as two groups of four digits separated by a hyphen (e.g.

The International Bank Account Number (IBAN) is a standardized international system for identifying bank accounts across national borders. The primary purpose of the IBAN is to facilitate the processing of cross-border transactions and to ensure that international payments are routed correctly. An IBAN is composed of several components: 1. **Country Code**: The first two letters represent the country where the bank is located, following the ISO 3166-1 alpha-2 code.

The International Mobile Equipment Identity (IMEI) is a unique identifier assigned to mobile devices, such as smartphones and tablets, that connect to cellular networks. The IMEI is typically a 15-digit number, although it can be longer in some cases due to additional information included in the identifier. The primary purposes of the IMEI include: 1. **Device Identification**: Each mobile device has a unique IMEI number that distinguishes it from all other devices.

The International Standard Music Number (ISMN) is a unique identifier assigned to notated music, similar to how the International Standard Book Number (ISBN) is used for books. The ISMN system was developed to provide a way to identify and catalog music scores and notated music publications, facilitating their distribution and sales. An ISMN consists of 13 digits and is typically formatted as follows: "979-0-xxx-xxxxx-x".

The group-0 ISBN publisher codes refer to the United States publisher codes within the International Standard Book Number (ISBN) system. Each ISBN is divided into several parts, including a prefix element (which is currently only '978' or '979'), a registration group element (indicating a particular country or language area), a publisher element (identifying a specific publisher), and an item number (representing a specific edition or format of a book).

A hash function is a mathematical algorithm that transforms an input (or 'message') into a fixed-size string of bytes. The output is typically a 'digest' that uniquely represents the input data, but even a small change in input will produce a significantly different output. Hash functions are widely used in various applications, including data integrity verification, digital signatures, password storage, and more. Here’s a list of well-known hash functions, categorized by their families: ### Cryptographic Hash Functions 1.

The Luhn algorithm, also known as the "modulus 10" or "mod 10" algorithm, is a simple checksum formula used to validate various identification numbers, such as credit card numbers. It was developed by IBM scientist Hans Peter Luhn in 1954. ### Steps of the Luhn Algorithm: 1. **Starting from the rightmost digit (the check digit) and moving left**, double the value of every second digit.

The Luhn algorithm, also known as the "modulus 10" algorithm, is a simple checksum formula used to validate a variety of identification numbers, particularly credit card numbers. However, when you mention "Luhn mod N," you are referring to a generalization of the Luhn algorithm that can be adapted to use different modulus bases (N). ### Overview of the Luhn Algorithm: 1. **Starting from the rightmost digit**, take each digit from the number.

MD5, which stands for Message-Digest Algorithm 5, is a widely used cryptographic hash function that produces a 128-bit (16-byte) hash value. It is commonly expressed as a 32-character hexadecimal number.

The Message Authentication Code (MAC) is a cryptographic technique that ensures the integrity and authenticity of a message. A Message Authentication Code is a short piece of information used to authenticate a message and confirm its integrity. Essentially, it helps to verify that a message has not been altered during transmission and that it comes from a legitimate sender. ### Key Features of MAC: 1. **Integrity**: Ensures that the message has not been altered in transit.

SHA-1, which stands for Secure Hash Algorithm 1, is a cryptographic hash function that produces a 160-bit (20-byte) hash value, typically rendered as a 40-digit hexadecimal number. It was designed by the National Security Agency (NSA) in 1993 and is part of the SHA family of hash functions defined by the National Institute of Standards and Technology (NIST).

SM3 is a cryptographic hash function that was designed in China. It is part of the SM (Shenzhen Mall) series of cryptographic standards developed and published by the Chinese government. SM3 produces a fixed-size output of 256 bits and is similar in purpose to other well-known hash functions like SHA-256. ### Key Characteristics of SM3: 1. **Output Size**: SM3 produces a hash value that is 256 bits (32 bytes) long.

The SYSV checksum, often associated with the System V Release (SYSV) Unix operating system, refers to a checksum algorithm used in the context of shared memory segments and semaphores. More specifically, it is commonly used in System V IPC (Inter-Process Communication) mechanisms to ensure data integrity. In many Unix-like systems, when working with shared memory or message queues, a checksum can validate that the data being accessed has not been corrupted.

Simple file verification is a process used to ensure that a file has not been altered, corrupted, or tampered with since it was created or last verified. This is often done by checking the file against a known, trusted version or by using checksums and hashes. Here are some common methods of simple file verification: 1. **Checksum Verification**: A checksum is a value derived from the contents of a file.

A Universal Product Code (UPC) is a standardized barcode used to uniquely identify products in retail and inventory management. It is typically represented as a series of black bars and numbers, which can be scanned by barcode readers to quickly retrieve product information. A UPC is made up of 12 digits: 1. **The first six digits** represent the manufacturer's identification number, assigned by the GS1 organization. 2. **The next five digits** indicate the specific product, assigned by the manufacturer.

The Verhoeff algorithm is an error detection method used primarily for validating identifiers, such as in various forms of numerical codes (e.g., ISBNs, credit card numbers, etc.). It is particularly good at catching single-digit errors, adjacent transpositions, or even some types of multiple errors. ### Key Features of the Verhoeff Algorithm: 1. **Base**: The algorithm operates in base 10, which means it uses the digits 0-9.