Improved techniques to update software in electronic devices that are already in use are disclosed. In one embodiment, software can be updated in a secure and controlled manner using cryptography. The authenticity of the updated software as well as its appropriateness for the particular electronic device can be confirmed prior to update. The software can also be updated on a per module basis. In one embodiment, a server hosts software updates for various electronic devices, and supplies the appropriate software update to the electronic devices via a data network.