Patent ID: 8602306

Claim:
A protection device for a contactless communication object ( 3 ) with a smart circuit ( 31 , 32 ) storing sensitive information or information giving access to services, the protection device ( 1 ) comprising: at least one radio receiver ( 13 ) for receiving first radio signals (S 22 ) emitted by a contactless reader or terminal ( 2 ), in a range of frequencies of the order of one megahertz to a few tens of megahertz, the first received signals (S 22 ) generating the power for operating the protection device ( 1 ) in order to enable a circuit ( 11 ) of the protection device ( 1 ) to generate a scrambling signal (f) to be emitted by a radio emitter ( 14 ) of the protection device as scrambling radio waves (S 21 ) intended for the terminal ( 2 ) or the reader, the scrambling radio waves (S 21 ) being produced by the circuit ( 11 ) upon receiving the first signals with sufficient power so as to be received by a radio receiver of the terminal ( 2 ) or the reader, and to deteriorate the reception by the radio receiver of the terminal ( 2 ) or the reader of second radio signals emitted by the contactless communication object ( 3 ), in response to enabling by the terminal ( 2 ) or the reader; a switch ( 12 ) for validating or invalidating the scrambling by the protection device ( 1 ), the switch ( 12 ) of the protection device ( 1 ) being controlled according to the result of a comparison carried out by a means for comparison between a piece of information stemming from a means for interactive authentication ( 1010 , 1011 , 1012 , 1015 ) of the protection device on the one hand, and a piece of information stored in the memory storage means of the protection device ( 1 ) on the other hand; and a smart circuit, wherein the smart circuit ( 114 ) requires minimal power resources for operation in favor of the energy used by the radio emitter ( 14 ) of the protection device ( 1 ) to have maximum emission power for at least one scrambling signal (S 21 ).