SHA1 digest algorithm

modulename: sha1_generic.ko

and/or

sha1.ko

configname: CONFIG_CRYPTO_SHA1

Linux Kernel Configuration
└─>Cryptographic options
└─>SHA1 digest algorithm
In linux kernel since version 2.6.12  
SHA-1 secure hash standard (FIPS 180-1/DFIPS 180-2).

source code:
crypto/sha1.c

depends
CONFIG_CRYPTO

is selected by
CONFIG_RPCSEC_GSS_KRB5