Methods and systems are provided for document encryption. In one embodiment, an adaptation engine is provided for partial encryption of a document. The adaptation engine may include a paginator for paginating the document into at least one sub-page according to characteristics of a specific device class. The adaptation engine may further include an encryptor for separately encrypting a to-be-encrypted element of the at least one sub-page using a partial encryption mechanism known by a client device that belongs to the specific device class.