Cipher text validation

A method of operating a device to receive data content in a network, the method comprising:

• receiving encrypted data content from another device in the network, the data content having been encrypted with a symmetric key shared with a trusted data content publisher device;
• requesting, from the trusted data content publisher device, a subset of the encrypted data content received from said another device in the network;
• and
• verifying whether or not the subset of the encrypted data content received from the trusted data content publisher device matches a selected section of the encrypted data content received from said another device in the network;
• to thereby determine that the encrypted data content received from said another device can be trusted.

A data publishing device configured to distribute data content to receiving devices in a network, the data publishing device comprising:

• a processing unit;
• and
• a memory, said memory containing instructions executable by said processing unit;
• wherein, upon executing the instructions, the processing unit is configured to operate the data publishing device to:
• encrypt the data content with a secret encryption key shared with the receiving devices;
• distribute the encrypted data content to at least one of the receiving devices;
• send a subset of the encrypted data content to at least a second one of the receiving devices upon request by the second one of the receiving devices, whereupon the second one of the receiving devices downloads the encrypted data content from one or more other receiving devices in the network.

A device configured to receive data content in a network, the device comprising:

• a processing unit;
• and
• a memory, said memory containing instructions executable by said processing unit;
• wherein, upon executing the instructions, the processing unit is configured to operate the device to:
• receive encrypted data content from another device in the network, the data content having been encrypted with a symmetric key shared with a trusted data content publisher device;
• request, from the trusted data content publisher device, a subset of the encrypted data content received from said another device in the network;
• and
• verify whether or not the subset of the encrypted data content received from the trusted data content publisher device matches a selected section of the encrypted data content received from said another device in the network to thereby determine that the encrypted data content received from said another device can be trusted.