Secure distribution of digital content

Abstract

A computer-implemented method for secure processing of a usage key or transfer of a usage key between a server and a data processing device, the usage key encodable to execute a cryptographic operation comprises: receiving, at the data processing device, the usage key encrypted according to a transportation encryption algorithm; processing, at the data processing device, the encrypted usage key with a modified version of a decryption routine of the transportation encryption algorithm, wherein the modified version of the decryption routine is such that it returns a modified version of the usage key, different from the usage key; and converting, at the data processing device, the modified version of the usage key into an encoding of the usage key, the encoding of the usage key operable to execute the cryptographic operation using the encoding of the usage key.

Dependencies are inferred from the claim text.