Crypto++ source code is available from SourceForge.net. The latest code (including bug fixes) can be found at the project page.
If using a SVN client, point your Repo-Browser to https://cryptopp.svn.sourceforge.net/svnroot/cryptopp. Or issue the following from the command line:
$ svn checkout https://svn.code.sf.net/p/cryptopp/code/trunk/c5 cryptopp
When it comes time to sync because the SVN sources have changed on SourceForge, issue:
$ svn update
Finally, if you are only interested in a checkout upto a specific version, use the -r option. For example, to fetch Crypto++ revision 496, issue the following.
$ svn checkout -r 496 https://svn.code.sf.net/p/cryptopp/code/trunk/c5 cryptopp-r496
If prompted to verify a finger print, the prompt is for the server's finger print.
Once downloaded, issue the following under GNU Linux to build the archive, shared object, and test program. See Linux for full details (and information on FreeBSD and OpenBSD).
cd cryptopp make static dynameic test sudo make install PREFIX=/usr/local