Man pages matching name asn1_decode_simple_der in section 3:

asn1_decode_simple_der.3.en	debian 10 / libtasn1-6-dev
asn1_decode_simple_der.3.en	debian 11 / libtasn1-6-dev
asn1_decode_simple_der.3.en	debian 12 / libtasn1-6-dev