HMAC256(1) Libgcrypt HMAC256(1) (NAME) hmac256 - HMAC-SHA-256 (SYNOPSIS) hmac256 [--binary] key [FILENAME] (DESCRIPTION) HMAC-SHA-256 (MAC) HMAC-SHA-256 . Libgcrypt . (stack) . config.h . hmac256 : hmac256 "This is my key" foo.txt MAC `foo.txt' . (OPTIONS) hmac256 : --binary MAC (). MAC . --version . (SEE ALSO) sha256sum(1) Libgcrypt 1.12.3 2026-08-27 HMAC256(1)