A system and method is provided for secure file and document management and editing by local client devices. An exemplary method includes receiving by a server, an identifier of a data block and a portion of the data block from a client device, encrypting the first portion of the data block, and generating an encryption key based on the identifier of the data block. The method further includes transmitting, by the server, the encrypted first portion of the data block to the client device to be stored locally in memory of the client device, and causing a second portion of the data block to be encrypted by the client device using the encryption key. A as result, the encrypted second portion of the data block can be stored in the memory of the client device in connection with the encrypted first portion of the data block.