It appears that there may be a problem with the Makefile for this package. The "libcrypto___la_SOURCES" macro does not reference the "blake2.cpp" source file, although it ought to.
https://sources.debian.org/src/libcrypto++/5.6.4-8/blake2.cpp/ https://sources.debian.org/src/libcrypto++/5.6.4-8/debian/autotools/Makefile.am/ This may be why the BLAKE2 module does not get included in the dynamic library, and the linker fails to resolve the associated symbols. Please review the list of object modules which are to be included in the static and dynamic libraries provided by this source package.
