CONFIG_CRYPTO_TWOFISH_X86_64 is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

Twofish cipher algorithm (x86_64)

modulename: twofish-x86_64.ko

configname: CONFIG_CRYPTO_TWOFISH_X86_64

Linux Kernel Configuration
└─>Cryptographic API
└─>Twofish cipher algorithm (x86_64)
In linux kernel since version 2.6.19 (release Date: 2006-11-29)  
Twofish cipher algorithm (x86_64).

Twofish was submitted as an AES (Advanced Encryption Standard)
candidate cipher by researchers at CounterPane Systems. It is a
16 round block cipher supporting key sizes of 128, 192, and 256
bits.

See also:
<http://www.schneier.com/twofish.html>

source code: