Method and system for transferring information using an encryption mode indicator

A system for transferring information, said system comprising:

• a source device that encodes an encryption mode identifier (EMI) code into an information packet and that transmits said encoded information packet over a communication interface, said source device comprising:
• a common encryption circuit that encrypts data of said encoded information packet based on a first key if said EMI code indicates a first mode, wherein said common encryption circuit also encrypts data of said encoded information packet based on a second key if said EMI code indicates a second mode;
• and
• a sink device that receives said encoded information packet from said communication interface, said sink device comprising:
• an extractor circuit within said sink device that extracts said EMI code from said received information packet, wherein said EMI code corresponds to a key that encrypts said information packet;
• and
• a common decryption circuit that decrypts said data of said received information packet using said second key in response to said extractor circuit indicating that said EMI code is of said second mode,
• wherein an unauthorized change in said EMI code from said first mode to said second mode, after encrypting said information packet at said common encryption circuit, causes decryption of said received information packet with said second key, rendering said information packet inaccessible;
• and
• wherein said first mode is a copy prohibition mode indicating that said information packet is not to be reproduced by said sink device and wherein said second mode is a copy once inhibition mode indicating that said information packet is not to be reproduced more than once by said sink device.

A method of transferring information that contains copy protection modes comprising:

• a source device receiving an information packet having a copy protection mode;
• said source device storing an encryption mode indicator (EMI) code into a header of said information packet depending on said copy protection mode;
• said source device using a first encryption mechanism to encrypt data of said information packet if said EMI code is of a first mode;
• said source device using a second encryption mechanism to encrypt said data of said information packet if said EMI code is of a second mode;
• said source device not encrypting said data of said information packet if said EMI code is of a third mode;
• and
• said source device transmitting said information packet to a sink device, wherein said first mode is a copy prohibition mode indicating that said information packet is not to be reproduced by said sink device, said second mode is a copy once inhibition mode indicating that said information packet is not to be reproduced more than once by said sink devices and said third mode is an unrestricted mode indicating that said information packet can be freely reproduced by said sink device;
• wherein an unauthorized change in said EMI code, after encrypting said information packet, causes decryption of said received information packet based on a wrong EMI code, rendering said information packet inaccessible.