https://www.cryptopp.com/
https://debian.pkgs.org/sid/debian-main-amd64/libcrypto++6_5.6.4-9_amd64.deb.html
https://www.cryptopp.com/docs/ref/
https://www.cryptopp.com/wiki/

/usr/include/crypto++/
/usr/share/doc/libcrypto++-dev/Readme.txt.gz








adding /dev/random to entropy - 
mbedtls_entropy_add_source( &entropy, dev_random_entropy_poll,
                                        NULL, DEV_RANDOM_THRESHOLD,
                                        MBEDTLS_ENTROPY_SOURCE_STRONG ) ) != 0 )