This implies that if the server is hostile to the client, then the server wins and the client is doomed. Correspondingly, it is a futile endeavour to try to protect the client computations from the server. From this (somewhat simplistic) argument, we may conclude that it makes little sense to encrypt data on the client; just use SSL, send the data to server, and let the server do its job. The server is trusted, which means that if the server wants to betray you, then you are defenceless.
(Note that all of the above applies even if your protocol is rock-solid from a cryptographic point of view -- and not many cryptographers would dare pretend that they can accomplish such a feat by themselves, without extensive peer review.)