Because of patent concerns support for MDC-2 has been disabled in OpenSSL on most Linux distributions and is not implemented by many other cryptographic libraries.
The algorithm itself is available in OpenSSL, but it is not compiled in. If you really want to use it, download the source package, modify the
debian/rules file so that this line:
CONFARGS = --prefix=/usr --openssldir=/usr/lib/ssl --libdir=lib/$(DEB_HOST_MULTIARCH)\
no-idea no-mdc2 no-rc5 no-zlib no-ssl3 enable-unit-test no-ssl3-method enable-rfc3779\
does not include
no-mdc2 and compile it (it might be as simple as
dpkg-buildpackage -us -uc).
Otherwise use aes-256 with something like sha256.