Method and systems for protecting data on a mobile handset when remotely activated by a user involve encrypting the data using an encryption key, storing the encrypted data, and deleting the non-encrypted data along with the encryption key. Data may also be uploaded to a server to via a cellular data call for use in backing up the mobile handset. A mobile handset application configures the handset to receive activation commands from a server to encrypt, upload or download data. The encryption key is either received from the server or generated by the mobile handset and communicated to the server. Mock data files may be generated and stored on the mobile handset to enable handset applications to function normally after the data files have been encrypted.