The CRC polynomial is the one used in ADCCP (ANSI X3.66, the US version of the X.25) [21].
This polynomial generates a 32 bit CRC value.
The CRC register is reset to zero when it is negotiated to start using this integrity type. The register will not be reset later in order to maintain the linkage between each integrity-checked data block.
The CRC is calculated for the data block, and encrypted using IDEA in modified CFB mode as described in chapter 3.4.4. This encrypted CRC value is the integrity information sent in a INTEGRITY INFO sub-negotiation sequence to the receiver.