A method of generating cryptographically protected digital data, the digital data encoding content and arranged into messages, each message being decodable by a decoder application on a client terminal having an interface to assemble each message for the decoder application, the method including: retrieving a message from a machine-readable medium; separating the message into a first and at least one further message section; encrypting at least part of the message, wherein said encrypting comprises encrypting each message section in such a way as to be decryptable independently of the other message sections; generating an encrypted message by adding a resynchronisation marker to each encrypted further message section, wherein said resynchronisation marker separates said encrypted further message section from an adjacent encrypted message section and includes explicit synchronisation information for resetting a cipher for decryption of said encrypted further message section; and providing the encrypted message as an output for a server interface configured to arrange the encrypted message into at least one packet including at least one header and a payload, each payload including a unique part of the encrypted message, at least one header including information enabling the interface on the client terminal to assemble the message for the decoder application from the payload of the packets; wherein either: (a) encrypting each message section uses a cipher in a cryptographic mode that uses feedback, wherein the cipher is re-initialised with a corresponding initialisation vector at the start of each message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number used as the initialization vector for the encryption of said encrypted further message section; or (b) encrypting each message section uses a cipher in a counter mode, wherein a counter of the counter mode is re-set before encrypting said message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number that is used to form the counter for the encryption of said encrypted further message section. retrieving a message from a machine-readable medium; separating the message into a first and at least one further message section; encrypting at least part of the message, wherein said encrypting comprises encrypting each message section in such a way as to be decryptable independently of the other message sections; generating an encrypted message by adding a resynchronisation marker to each encrypted further message section, wherein said resynchronisation marker separates said encrypted further message section from an adjacent encrypted message section and includes explicit synchronisation information for resetting a cipher for decryption of said encrypted further message section; and providing the encrypted message as an output for a server interface configured to arrange the encrypted message into at least one packet including at least one header and a payload, each payload including a unique part of the encrypted message, at least one header including information enabling the interface on the client terminal to assemble the message for the decoder application from the payload of the packets; wherein either: (a) encrypting each message section uses a cipher in a cryptographic mode that uses feedback, wherein the cipher is re-initialised with a corresponding initialisation vector at the start of each message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number used as the initialization vector for the encryption of said encrypted further message section; or (b) encrypting each message section uses a cipher in a counter mode, wherein a counter of the counter mode is re-set before encrypting said message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number that is used to form the counter for the encryption of said encrypted further message section. (a) encrypting each message section uses a cipher in a cryptographic mode that uses feedback, wherein the cipher is re-initialised with a corresponding initialisation vector at the start of each message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number used as the initialization vector for the encryption of said encrypted further message section; or (b) encrypting each message section uses a cipher in a counter mode, wherein a counter of the counter mode is re-set before encrypting said message section, and wherein the explicit synchronisation information of the resynchronisation marker added to each encrypted further message section comprises a unique sequence number that is used to form the counter for the encryption of said encrypted further message section.