Secure Distribution of Watermarked Content

System for enabling secure delivery and watermarking of a content item X, the system comprising:

• a key generator comprising a key generating algorithm for generating an encryption key e for said encryption unit and a decryption key d and a split-key algorithm for splitting e into i different split-encryption keys e1, e2, . . . , ei and/or for splitting d into k different split-decryption keys d1, d2, . . . , dk respectively wherein i, k≧1 and i+k>2;
• wherein when executing i consecutive encryption operations and k consecutive decryption operations on content item X using said split-encryption and split-decryption keys respectively, generates content item X (Ddk(Ddk-1( . . . (Dd2(Dd1(Eei(Eei−1( . . . (Ee2(Ee (X)) . . . ))=X);
• one or more encryption units for encrypting or partially encrypting at least a first content part of said content item using a first encryption algorithm E;
• and using said encryption key e or at least one of said split-encryption keys e1, e2, . . . , ei respectively;
• one or more decryption units comprising a decryption algorithm D and being configured for partially decrypting or decrypting an encrypted or partially encrypted first content part respectively on the basis of said first decryption algorithm D;
• and on the basis of at least one of said split-decryption keys d1, d2, . . . , dk;
• at least one watermark embedding module configured for embedding one or more encrypted, partially encrypted or partially decrypted perturbations in an encrypted, partially encrypted or partially decrypted first content part respectively, wherein a perturbation represents at least a part of a watermark.

A content delivery network for enabling secure delivery and watermarking of at least part of a content item X to a content consumption unit using a split-key cryptosystem comprising encryption and decryption algorithms E and D, a key generating algorithm for generating encryption and decryption keys e, d, a split-key algorithm for splitting e into i different split-encryption keys e1, e2, . . . , ei and/or for splitting d into k different split-decryption keys d1, d2, . . . , dk respectively wherein i, k≧1 and i+k>2;

• wherein when executing i consecutive encryption operations and k consecutive decryption operations on content item X using said split-encryption and split-decryption keys respectively, generates a fully decrypted content item X (Ddk(Ddk-1( . . . (Dd2(Dd1(Eei(Eei-1( . . . (Ee2(Ee1(X)) . . . ))=X);
• said content delivery network comprising:
• an encryption unit for encrypting or partially encrypting at least a first content part of said content item using a first encryption algorithm E;
• and, using said encryption key e or at least one of said split-encryption keys e1, e2, . . . , ei;
• and/or,
• a decryption unit comprising a decryption algorithm D and being configured for decrypting an encrypted or partially encrypted first content part on the basis of said first decryption algorithm D;
• and, on the basis of at least one of said split-decryption keys d1, d2, . . . , dk;
• a watermark embedding module configured for
• receiving at least an encrypted, partially encrypted or partially decrypted first content part and one or more encrypted, partially encrypted or partially decrypted perturbations respectively, wherein a perturbation represents at least part of a watermark
• embedding said one or more encrypted, partially encrypted or partially decrypted perturbations in said encrypted, partially encrypted or partially decrypted first content part respectively, a perturbation representing at least part of a watermark;
• and,
• at least one content delivery node configured for storing one or more encrypted content items and for delivering a partially decrypted watermarked content item to said content consumption unit.

A watermark embedding module for use with a split-key cryptosystem, said split-key cryptosystem comprising encryption and decryption algorithms E and D, a key generating algorithm for generating encryption and decryption keys e, d, a split-key algorithm for splitting e into i different split-encryption keys e1, e2, . . . , ei and/or for splitting d into k different split-decryption keys d1, d2, . . . , dk respectively wherein i, k≧1 and i+k>2;

• wherein when executing i consecutive encryption operations and k consecutive decryption operations on content item X using said split-encryption and split-decryption keys respectively, generates a fully decrypted content item X (Ddk(Ddk-1( . . . (Dd2(Dd1(Eei(Eei-1( . . . (Ee2(Ee1(X)) . . . ))=X);
• said watermark embedding module being configured for:
• receiving at least one of an encrypted, partially encrypted or partially decrypted first content part and one or more encrypted, partially encrypted or partially decrypted perturbations respectively, wherein a perturbation represents at least part of a watermark;
• and
• embedding said one or more encrypted, partially encrypted or partially decrypted perturbations in said at least one of an encrypted, partially encrypted or partially decrypted first content part respectively, a perturbation representing at least part of a watermark.