How do I implement encryption/hashing on the client for no SSL scenarios?

In my aspnet_Membership table are fields like Password, PasswordFormat and PasswordSalt. How to know the format in which the password is stored (MD5/SHA1?). Say, if PasswordFormat=2 what does it mean? Additionally, in a scenario where SSL is absent, I wanted to have some client-side .js code to implement SHA1+salt encryption/hashing on the client as well as some sort of token-based challenge/response system on the server to validate my password.  Would be thankful if someone can point me to some resources on how to implement it.

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