ChaCha

modulename: chacha_generic.ko

configname: CONFIG_CRYPTO_CHACHA20

Linux Kernel Configuration
└─>Cryptographic API
└─>Length-preserving ciphers and modes
└─>ChaCha
In linux kernel since version 3.10 (release Date: 2013-06-30)  
The ChaCha20, XChaCha20, and XChaCha12 stream cipher algorithms

ChaCha20 is a 256-bit high-speed stream cipher designed by Daniel J.
Bernstein and further specified in RFC7539 for use in IETF protocols.
This is the portable C implementation of ChaCha20. See
https://cr.yp.to/chacha/chacha-20080128.pdf for further information.

XChaCha20 is the application of the XSalsa20 construction to ChaCha20
rather than to Salsa20. XChaCha20 extends ChaCha20's nonce length
from 64 bits (or 96 bits using the RFC7539 convention) to 192 bits,
while provably retaining ChaCha20's security. See
https://cr.yp.to/snuffle/xsalsa-20081128.pdf for further information.

XChaCha12 is XChaCha20 reduced to 12 rounds, with correspondingly
reduced security margin but increased performance. It can be needed
in some performance-sensitive scenarios.

source code: