Method for identifying a device used by a hacked terminal, and related device

A method for producing a control word k′, comprising:

• a step of receiving, by an electronic device, an encrypted control word c from a terminal,
• a step of applying to the encrypted control word c a decryption function D by a processor of said electronic device, and thus of calculating a decrypted word k such that k=D(c), wherein the decrypted word k comprises a component v, and
• a step of selectively producing a control word k′ according to the result of a comparison operation between the value of v and that of an identifier i that is exclusive to the device, and
• a step of issuing said control word k′to said terminal by said electronic device, said terminal being configured to decode content based on the issued control word k′ such that, if the issued control word k′ is identical to k, the content is decoded correctly, and, if the issued control word k′ is distinct from k, said terminal is unable to decode the content, wherein:
• the identifier i is a vector of z integers with values i=(i, . . . , iz)contained in a set [1,m], m and z being integers higher than 1;
• the component v is a vector of z integers with values v =(v, . . . , vz)contained in a set [0,m];
• and the step of producing the control word k′ comprises producing a word that is:
• identical to k if the value of each integer vl, is respectively lower than the value of each integer il, for every l between 1 and z,
• distinct from k, if the value of each integer vl, is respectively greater than or equal to the value of each integer il, for every l between 1 and z.

A method for producing a control word k′, comprising:

• a step of receiving, by an electronic device, an encrypted control word c from a terminal,
• a step of applying to the encrypted control word c a decryption function D by a processor of said electronic device, and thus of calculating a decrypted word k such that k=D(c), wherein the decrypted word k comprises a component v,
• a step of selectively producing a control word k′ that is distinct from k according to the result of a comparison operation between the value of v and that of an identifier i that is exclusive to the device, wherein the control word comprises a component t,
• a step of interpreting said component t in order to produce the control word k′ from v, i and k, and
• a step of issuing said control word k′ to said terminal by said electronic device, said terminal being configured to decode content based on the issued control word k′ such that, if the issued control word k′ is identical to k, the content is decoded correctly, and, if the issued control word k′ is distinct from k, said terminal is unable to decode the content.

An electronic device interacting with a terminal, said device comprising:

• an interface for receiving an encrypted control word c from the terminal;
• a processor for producing a control word k′ according to said encrypted control word c;
• an interface for providing, to said terminal, said control word produced in response to receiving the encrypted control word c, and
• a memory storing an identifier i,
• wherein said processor produces the control word k′ by the following steps:
• a step of receiving, by the electronic device, the encrypted control word c from the terminal,
• a step of applying to the encrypted control word c a decryption function D by the processor of said electronic device, and thus of calculating a decrypted word k such that k=D(c), wherein the decrypted word k comprises a component v,
• a step of selectively producing the control word k′ that is distinct from k according to the result of a comparison operation between the value of v and that of the identifier i that is exclusive to the device, wherein the control word comprises a component t,
• a step of interpreting said component t in order to produce the control word k′ from v, i and k, and
• a step of issuing said control word k′ to said terminal by said electronic device, said terminal being configured to decode content based on the issued control word k′ such that, if the issued control word k′ is identical to k, the content is decoded correctly, and, if the issued control word k′ is distinct from k, said terminal is unable to decode the content.

An electronic device interacting with a terminal, said device comprising:

• an interface for receiving an encrypted control word c from the terminal;
• a processor for producing a control word k′ according to said encrypted control word c;
• an interface for providing, to said terminal, said control word produced in response to receiving the encrypted control word c, and
• a memory storing an identifier i,
• wherein said processor produces the control word k′ by the following steps:
• a step of receiving, by an electronic device, an encrypted control word c from a terminal,
• a step of applying to the encrypted control word c a decryption function D by a processor of said electronic device, and thus of calculating a decrypted word k such that k=D(c), wherein the decrypted word k comprises a component v,
• a step of selectively producing a control word k′ that is distinct from k according to a result of a comparison operation between the value of v and that of an identifier i that is exclusive to the device, wherein the control word k′ is:
• identical to k if the value of the component v is lower than the value of the identifier l;
• and
• distinct from k if the value of the component v is greater than or equal to the value of the identifier l, and
• a step of issuing said control word k′ to said terminal by said electronic device, said terminal being configured to decode content based on the issued control word k′ such that, if the issued control word k′ is identical to k, the content is decoded correctly, and, if the issued control word k′ is distinct from k, said terminal is unable to decode the content.

An electronic device interacting with a terminal, said device comprising:

• an interface for receiving an encrypted control word c from the terminal;
• a processor for producing a control word k′ according to said encrypted control word c;
• an interface for providing, to said terminal, said control word produced in response to receiving the encrypted control word c, and
• a memory storing an identifier i,
• wherein said processor produces the control word k′ by the following steps:
• a step of receiving, by an electronic device, an encrypted control word c from a terminal,
• a step of applying to the encrypted control word c a decryption function D by a processor of said electronic device, and thus of calculating a decrypted word k such that k=D(c), wherein the decrypted word k comprises a component v, and
• a step of selectively producing a control word k′ according to the result of a comparison operation between the value of v and that of an identifier i that is exclusive to the device, and
• a step of issuing said control word k′ to said terminal by said electronic device, said terminal being configured to decode content based on the issued control word k′ such that, if the issued control word k′ is identical to k, the content is decoded correctly, and, if the issued control word k′ is distinct from k, said terminal is unable to decode the content, wherein:
• the identifier i is a vector of z integers with values i=(i, . . . , iz)contained in a set [1,m], m and z being integers higher than 1;
• the component v is a vector of z integers with values v=(v, . . . ,vz) contained in a set [0,m];
• and the step of producing the control word k′ comprises producing a word that is:
• identical to k if the value of each integer vl, is respectively lower than the value of each integer il, for every l between 1 and z,
• distinct from k if the value of each integer vl, is respectively greater than or equal to the value of each integer il, for every l between 1 and z.