http://cryptopals.com http://cryptopals.com - This is probably the best place to start. For general application and network security (not specifically crypto),

http://cryptopals.com http://cryptopals.com - This is probably the best place to start. For general application and network security (not specifically crypto), we (the company I work for) are trying to make this a great resource for self-education: https://github.com/paragonie/awesome-appsec https://github.com/paragonie/awesome-appsec