Just a heads-up: tarsnap (v1.0.37) will not compile with headers from the openssl v1.1.0 series. This is (from what I can see) due to changes in the definition of “struct rsa_st” in rsa.h which makes that structure “anonymous”. Compiling with openssl v1.0.2 series works perfectly. (My environment is MacOS 10.12.3, but this is probably OS-independent.) /steve holmes