True, but I'm just talking about the sizes of the binaries generated by the default settings of common compilers (gcc, in the case of oathtool), for comparing o

True, but I'm just talking about the sizes of the binaries generated by the default settings of common compilers (gcc, in the case of oathtool), for comparing orders of magnitude. I'm sure there's plenty of fat you could trim by simply tuning the compilation a bit. (Oathtool also supports SHA2, since it may be used by other implementations, per the RFC. )