What Is Checksum? One-Stop Guide for All You Need to Know About Checksum

With the increase in the data and information exchange over the network channels, the need to detect any error or damage to the transmitted data becomes a necessary part of the process, and this issue is resolved using the checksum method.

This article on ‘What Is Checksum?’ will look into multiple steps involved in working the network checksum model.

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What Is Checksum?

The checksum is a network method to check for any error or damage to the data transmitted to the sender side from the sender side. The checksum method applies the bit addition and bit complement method to perform the checksum implementation.

Why Apply Checksum?

The need to apply checksum or any other error-detection method is done simply to identify the damage to the data when it's being transmitted over the network channel.

The checksum uses the Checksum Generator on the sender side and the Checksum Checker on the receiver side.

Working Steps for Checksum

Steps involved in the checksum error-detection method:

Step 1: At the Sender Side,

  • Divide the original data into the ‘m’ number of blocks with ‘n’ data bits in each block.
  • Adding all the ‘k’ data blocks.
  • The addition result is complemented using 1’s complement.
  • The obtained data is known as the Checksum.

Step 2: Data Transmission

  • Integrate the checksum value to the original data bit.
  • Begin the transmission of data to the receiver side.

Step 3: At the Receiver Side,

  • Divide the received data into the ‘k’ number of blocks.
  • Adding all the ‘k’ data blocks along with the checksum value.
  • The addition result is complemented using 1’s complement.
  • Two possible cases after 1’s complement:
  • Case 1: If the result is 0.
    • No errors in the received data from the sender side.
    • The receiver accepts the data.
  • Case 2: If the result is not 0.
    • Errors in the received data from the sender side.
    • The receiver discards the data and requests for retransmission of data.

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Solved Example

Let’s use an example to implement the checksum method and consolidate our understanding of the network principle.

For the given data value 11001100 10101010 11110000 11000011, perform the checksum method.

1. The first step is to perform the bit addition of the given data bits at the sender side.


Note: The extra carry bits are added to the summation result.

2. Perform the 1’s Complement for the bit addition result, thus obtaining the checksum value.


3. Integrate the checksum value and the original data bit and begin the data transmission to the receiver.


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4. The receiver side will begin the Checksum Checker method, repeat the bit addition, and perform the 1’s complement.


5. If the complement result is 0, the data received is correct and without any error.


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In this article, we looked into the information related to working the error-detection network method, the checksum method.

You can refer to Simplilearn’s Cyber Security Expert course to further understand the working of the checksum method. By completing this professional course, you’ll become more proficient with terms related to network principles and more experienced in performing the checksum method.

If you have any questions about this article on ‘What Is Checksum?’. Feel free to mention them in the comment section at the bottom of this page. Our expert team will help you solve your queries at the earliest.

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