default or selected kernelversion does not have config value CONFIG_CRYPTO_RMD128.
Result is shown for kernelversion 6.9.9

RIPEMD-128 digest algorithm

modulename: rmd128.ko

configname: CONFIG_CRYPTO_RMD128

Linux Kernel Configuration
└─>Cryptographic API
└─>RIPEMD-128 digest algorithm
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
RIPEMD-128 (ISO/IEC 10118-3:2004).

RIPEMD-128 is a 128-bit cryptographic hash function. It should only
be used as a secure replacement for RIPEMD. For other use cases,
RIPEMD-160 should be used.

Developed by Hans Dobbertin, Antoon Bosselaers and Bart Preneel.
See <http://homes.esat.kuleuven.be/~bosselae/ripemd160.html>

source code: