A checksum is a small value mathematically derived from a message to detect changes during transmission. In wireless LAN security, it supports message integrity rather than confidentiality or availability. section 20.1.1 section 20.5
The integrity-check process is:
- The sender calculates a checksum from the plaintext message and appends it to the message. section 20.1.1
- The sender encrypts and transmits the message with its appended checksum. section 20.1.1
- The receiver decrypts the message, calculates a new checksum, and compares it with the received value. section 20.1.1
- The receiver accepts the message when the values match and discards it when they differ. section 20.1.1
A checksum does not stop tampering or prevent bit-flipping attacks. It enables the receiver to identify that the data was altered. section 20.1.1
Wireless message validation
A wireless sender appends a checksum to plaintext before encryption. After receiving and decrypting the message, the receiver recalculates the checksum; a mismatch causes the message to be discarded. section 20.1.1
