مقایسه تفاوت های Differences Between CRC And Checksum

DifferenceBetween · #1 05-09-2013

CRC vs Checksum

Anytime data is stored in a computer with the intent to transmit it, there is a need to ensure that the data is not corrupted. If corrupted data was sent, there would be inaccurate data transmitted and it may not work as desired. There is, therefore, a need for an error detection system that checks that all the data entered is okay and not corrupt before any encryption or transmission occurs. There are two main methods to check the data.

Checksum is arguably the oldest methods that has been used in the validation of all data prior to its being sent. Checksum also helps in authenticating data, as the raw data and the entered data should conform. If an anomaly is noticed, referred to as an invalid checksum, there is a suggestion that there may have been a data compromise in a given method.

Cyclic redundancy check, or CRC as it is commonly referred to, is a concept also employed in the validation of data. The principle used by CRC is similar to checksums, but rather than use the 8 byte system employed by Checksum in checking for data consistency, polynomial division is used in the determination of the CRC. The CRC is most commonly 16 or 32 bits in length. If a single byte is missing, an inconsistency is flagged in the data as it does not add up to the original.

Differences

One of the differences noted between the 2 is that CRC employs a math formula that is based on 16- or 32-bit encoding as opposed to Checksum that is based on 8 bytes in checking for data anomalies. The CRC is based on a hash approach while Checksum gets its values from an addition of all truncated data which may come in 8 or 16 bits. CRC, therefore, has a greater ability to recognize data errors as a single bit missing in the hash system which changes the overall result.

The checksum, on the other hand, requires less transparency and will provide for ample error detection as it employs an addition of bytes with the variable. It can, therefore, be said that the main purpose of CRC is to catch a diverse range of errors that may come about during the transmission of data in analog mode. Checksum, on the other hand, can be said to have been designed for the sole purpose of noting regular errors that may occur during software implementation.

CRC is an improvement over checksums. As earlier noted, checksums are a traditional form of computing, and CRC’s are just a mere advancement of the arithmetic that increases the complexity of the computation. This, in essence, increases the available patterns that are present, and thus more errors can be detected by the method. Checksum has been shown to detect mainly single-bit errors. However, CRC can detect any double-bit errors being observed in the data computation. In understanding the differences between the two data validation methods, knowledge is gathered as to why these two methods are used hand-in-hand in Internet protocol, as it reduces the vulnerability of Internet protocols occurring.

Summary :

- CRC is more thorough as opposed to Checksum in checking for errors and reporting.

- Checksum is the older of the two programs.

- CRC has a more complex computation as opposed to checksum.

- Checksum mainly detects single-bit changes in data while CRC can check and detect double-digit errors.

- CRC can detect more errors than checksum due to its more complex function.

- A checksum is mainly employed in data validation when implementing software.

- A CRC is mainly used for data evaluation in analogue data transmission.

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