Digest::HMAC_SHA1 (3pm) - Keyed-Hashing for Message Authentication
Digest::SHA1 (3pm)   - Perl interface to the SHA-1 algorithm
ldns_sign_public_rsasha1 (3) - (unknown subject)
ldns_verify_rrsig_rsasha1 (3) - (unknown subject)
sha1 (1ssl)          - message digests
sha1sum (1)          - compute and check SHA1 message digest