CONFIG_CRYPTO_XCTR (not configurable)

modulename: xctr.ko

configname: CONFIG_CRYPTO_XCTR

Linux Kernel Configuration
└─>Cryptographic API
└─>Length-preserving ciphers and modes
└─>CRYPTO_XCTR
In linux kernel since version 6 (release Date: 2022-10-02)  
XCTR (XOR Counter) mode for HCTR2

This blockcipher mode is a variant of CTR mode using XORs and little-endian
addition rather than big-endian arithmetic.

XCTR mode is used to implement HCTR2.

source code: