[LinuxBender]

I believe you will find most folks here will be against the concept of writing ones own encryption even if as a personal exercise. That said I am not a cryptologyst and can only suggest lurking on Cryptography and Security Stackexchange [1][2] for some time and then posting a detailed question/discussion on this topic. There may be other groups indirectly related to cryptography. [3] I personally think it is great you are taking on such a challenge and hope that you share here what you learned.

[1] - https://crypto.stackexchange.com/

[2] - https://security.stackexchange.com/

[3] - https://stackexchange.com/sites#