External security module for a television signal decoder

Claim 2

A security system for transmission of a signal comprising: encoder means for encoding said signal, said encoder means comprising: signal scrambling means for scrambling signal and outputting a scrambled signal and a key for descrambling said scrambled signal, first key encryptor means coupled to said signal scrambling means, for performing a first encryption on said key using a first confidential serial number and outputting a once-encrypted key, and second key encryptor means coupled to said first key encryptor means, for performing a further encryption on said once encrypted key using a second confidential serial number and outputting a twice-encrypted key, decoder means coupled to said transmission means for receiving and descrambling said scrambled signal, said decoder means comprising: first key decryptor means coupled to said transmission means, for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, a replaceable security module, removably attached to said decoder means and containing a second key decryptor means coupled to said first key decryptor means, for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said second key decryptor means and said transmission means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 3

The security system of claim 1, wherein said encoder means further comprises: key memory means coupled to said signal scrambling means and said first key encryptor means for storing said key.

Claim 4

The security system of claim 1, wherein said encoder means further comprises: a first confidential serial number database coupled to said first key encryptor means, containing a list of first confidential serial numbers.

Claim 5

The security system of claim 3, wherein said encoder means further comprises: a second confidential serial number database coupled to said second key encryptor means, containing a list of second confidential serial numbers.

Claim 6

The security system of claim 1, wherein said decoder means further comprises: second confidential serial number memory means coupled to said first key decryptor means, for storing a second confidential serial number.

Claim 7

The security system of claim 5, wherein said replaceable security module contains said first confidential serial number memory means.

Claim 8

A security system for transmission of a signal comporising: encoder means for encoding said signal, said encoder means comprising: signal scrambling means for scrambling signal and outputting a scrambled signal and a key for descrambling said scrambled signal, first key encryptor means coupled to said signal scrambling means, for performing a first encryption on said key using a first confidential serial number and outputting a once-encrypted key, and second key encryptor means coupled to said first key encryptor means, for performing a further encryption on said once encrypted key using a second confidential serial number and outputting a twice-encrypted key, decoder means coupled to said transmission means for receiving and descrambling said scrambled signal, said decoder means comprising: a replaceable security module, removably attached to said decoder means and containing a first key decryptor means coupled to said transmission means, for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, a second key decryptor means coupled to said first key decryptor means, for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said first second key decryptor means and said transmission means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 9

A security system for transmission of a signal comporising: encoder means for encoding said signal, said encoder means comprising: signal scrambling means for scrambling signal and outputting a scrambled signal and a key for descrambling said scrambled signal, first key encryptor means coupled to said signal scrambling means, for performing a first encryption on said key using a first confidential serial number and outputting a once-encrypted key, and second key encryptor means coupled to said first key encryptor means, for performing a further encryption on said once encrypted key using a second confidential serial number and outputting a twice-encrypted key, decoder means coupled to said transmission means for receiving and descrambling said scrambled signal, said decoder means comprising: a replaceable security module, removably attached to said decoder means and containing a first key decryptor means coupled to said transmission means, for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, a second key decryptor means coupled to said first key decryptor means, for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said first second key decryptor means and said transmission means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 10

The security system of claim 7, wherein said decoder means further comprises: first confidential serial number memory means coupled to said second key decryptor means for storing a first confidential serial number.

Claim 11

The security system of claim 1, wherein said decoder means further comprises: telephone interface means for transmitting and receiving data to and from a pay television provider, said data encrypted with a confidential telephone number.

Claim 12

The security system of claim 9, wherein an encrypted key is received via said telephone interface means.

Claim 13

The security system of claim 1, wherein said transmission means further comprises: first transmission means for transmitting said scrambled signal, and second transmission means for transmitting said twice-encrypted key.

Claim 14

The security system of claim 1, wherein said signal is a television signal.

Claim 15

The security system of claim 11, wherein said television signal is a B-MAC type television signal.

Claim 16

The security system of claim 1, wherein said encoder means further comprises: multiplexor means for multiplexing said twice-encrypted key with said scrambled signal prior to transmission.

Claim 17

The security system of claim 14, wherein said decoder further comprises: demultiplexor means for demultiplexing said twice-encrypted key from said scrambled signal.

Claim 18

A decoder for receiving and descrambling a signal which has been scrambled using a key which has been subsequently twice-encrypted, said decoder comprising: first key decryptor means for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, a replaceable security module, removably attached to said decoder and containing a second key decryptor means coupled to said first key decryptor means for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said second key decryptor means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 19

A decoder for receiving and descrambling a signal which has been scrambled using a key which has been subsequently twice-encrypted, said decoder comprising: first key decryptor means for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, a replaceable security module, removably attached to said decoder and containing a second key decryptor means coupled to said first key decryptor means for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said second key decryptor means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 20

The decoder of claim 16, further comprising: key memory means coupled to said signal descrambler means and said second key decryptor means for storing said decrypted key.

Claim 21

The decoder of claim 16, further comprising: second confidential serial number memory means coupled to said first key decryptor means, for storing a second confidential serial number.

Claim 22

A decoder for receiving and descrambling a signal which has been scrambled using a key which has been subsequently twice-encrypted, said decoder comprising: a replaceable security module, removably attached to said decoder and containing a first key decryptor means for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, second key decryptor means coupled to said first key decryptor means for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said second key decryptor means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 23

A decoder for receiving and descrambling a signal which has been scrambled using a key which has been subsequently twice-encrypted, said decoder comprising: a replaceable security module, removably attached to said decoder and containing a first key decryptor means for performing a first key decryption on said twice encrypted key using said second confidential serial number and outputting a partially decrypted key, second key decryptor means coupled to said first key decryptor means for performing a second key decryption on said partially decrypted key using a first confidential serial number and outputting a decrypted key, and signal descrambling means coupled to said second key decryptor means for descrambling said scrambled signal using said twice-decrypted key and outputting a descrambled signal.

Claim 24

The decoder of claim 16, further comprising: first confidential serial number memory means coupled to said second key decryptor means, for storing a first confidential serial number.

Claim 25

The decoder of claim 20, wherein said replaceable security module contains first confidential serial number memory means.

Claim 26

The decoder of claim 16, wherein said signal is a television signal.

Claim 27

The decoder of claim 16 further comprising: telephone interface means for transmitting and receiving data to and from a pay television provider, said data encrypted with a confidential telephone number.

Claim 28

The decoder of claim 23, wherein said twice-encrypted key is received via said telephone interface means.

Claim 29

The decoder of claim 22, wherein said television signal is a B-MAC type television signal.

Claim 30

The decoder of claim 16, wherein said scrambled signal and said twice-encrypted key have been multiplexed together prior to reception by the decoder.

Claim 31

The decoder of claim 24, further comprising: demultiplexor means for demultiplexing said twice-encrypted key from said scrambled signal.

Claim 34

The method of claim 28, wherein said second confidential security number is assigned to said decoder.

Claim 37

The method of claim 30, wherein said second confidential security number is assigned to said replaceable security module.

Claim 38

The method of claim 28, wherein said first confidential security number is assigned to said replaceable security module.

Claim 39

The method of claim 28, wherein said transmitting step further comprises: multiplexing said scrambled signal and twice-encrypted key together prior to transmission.

Claim 40

The method of claim 28, wherein said transmitting step further comprises: transmitting said scrambling signal and said twice-encrypted key as separate signals.

Claim 45

The method of claim 36 wherein said first confidential serial number is assigned to said decoder.

Claim 46

The method of claim 36, wherein said second confidential serial number is assigned to said replaceable security module.

Claim 47

The method of claim 35, wherein said second confidential serial number is assigned to said decoder.

Claim 48

The method of claim 35, wherein said first confidential serial number is assigned to said replaceable security module.

Claim 49

A decoder for receiving and descrambling a signal scrambled using a twice-encrypted key, said decoder comprising: connector means for connecting said decoder to a replaceable security module, through which connector means said twice-encrypted key is transmitted to said replaceable security module and a partially-decrypted key is received from said replaceable security module, key decryptor means, coupled to said connector means for performing a decryption on said partially-decrypted key using a second confidential serial number, and outputting a decrypted key, and signal descrambling means coupled to said key decryptor for descrambling said signal with said decrypted key and outputting a descrambled signal.

Claim 50

A decoder for receiving and descrambling a signal scrambled using a twice-encrypted key, said decoder comprising: connector means for connecting said decoder to a replaceable security module, through which connector means said twice-encrypted key is transmitted to said replaceable security module and a partially-decrypted key is received from said replaceable security module, key decryptor means, coupled to said connector means for performing a decryption on said partially-decrypted key using a second confidential serial number, and outputting a decrypted key, and signal descrambling means coupled to said key decryptor for descrambling said signal with said decrypted key and outputting a descrambled signal.

Claim 51

The decoder of claim 41, further comprising: key memory means coupled to said signal descrambling means and said key decryptor means for storing said decrypted key.

Claim 52

The decoder of claim 41, wherein said signal is a television signal.

Claim 53

The decoder of claim 41, wherein said television signal is a B-MAC type television signal.

Claim 54

The decoder of claim 41, wherein said scrambled signal and said twice-encrypted key signal have been multiplexed together prior to reception by the decoder.

Claim 55

The decoder of claim 45, further comprising: demultiplexor means for demultiplexing said twice-encrypted key signal from said scrambled signal.

Claim 56

The decoder of claim 41, further comprising: telephone interface means for transmitting and receiving data to and from a pay television provider, said data encrypted with a confidential telephone number.

Claim 57

The decoder of claim 47, wherein said twice-encrypted key is received via said telephone interface means.

Claim 58

A decoder for receiving and descrambling a signal scrambled using a twice-encrypted key, said decoder comprising: key decryptor means, for performing a first key decryption on said twice-encrypted key using a first confidential serial number and outputting a partially decrypted key, connector means, coupled to said key decryptor means for connecting said decoder to a replaceable security module, through which connector means said partially decrypted key is transmitted to said replaceable security module and a descrambling control signal is received from said replaceable security module, signal descrambling means, coupled to said connector means and receiving said descrambling control signal for descrambling said signal and outputting a descrambled signal.

Claim 59

A decoder for receiving and descrambling a signal scrambled using a twice-encrypted key, said decoder comprising: key decryptor means, for performing a first key decryption on said twice-encrypted key using a first confidential serial number and outputting a partially decrypted key, connector means, coupled to said key decryptor means for connecting said decoder to a replaceable security module, through which connector means said partially decrypted key is transmitted to said replaceable security module and a descrambling control signal is received from said replaceable security module, signal descrambling means, coupled to said connector means and receiving said descrambling control signal for descrambling said signal and outputting a descrambled signal.

Claim 60

The decoder of claim 49, wherein said signal is a television signal.

Claim 61

The decoder of claim 49, wherein said television signal is a B-MAC type television signal.

Claim 62

The decoder of claim 49, wherein said scrambled signal and said twice-encrypted key signal have been multiplexed together prior to reception by the decoder.

Claim 63

The decoder of claim 52, further comprising: demultiplexor means for demultiplexing said twice-encrypted key signal from said scrambled signal.

Claim 64

The decoder of claim 49 further comprising: telephone interface means for transmitting and receiving data to and from a pay television provider, said data encrypted with a confidential telephone number.

Claim 65

The decoder of claim 54, wherein said twice-encrypted key is received via said telephone interface means.

Claim 66

A replaceable security module for storing confidential serial number and performing a partial decryption of a twice-encrypted key and outputting a partially decrypted key, said replaceable security module comprising; connector means for connecting said replaceable security module to a decoder and through which a twice-encrypted key is received from said encoder and a partially decrypted key is transmitted to said decoder, memory means for storing at least a confidential serial number, and decryption means, coupled to said connector means and said memory means for performing a partial decryption on said twice-encrypted key and outputting a partially-decrypted key.

Claim 67

A replaceable security module for storing confidential serial number and performing a partial decryption of a twice-encrypted key and outputting a partially decrypted key, said replaceable security module comprising; connector means for connecting said replaceable security module to a decoder and through which a twice-encrypted key is received from said encoder and a partially decrypted key is transmitted to said decoder, memory means for storing at least a confidential serial number, and decryption means, coupled to said connector means and said memory means for performing a partial decryption on said twice-encrypted key and outputting a partially-decrypted key.

Claim 68

The replaceable security module of claim 56, wherein said memory means further comprises: security means for allowing the contents of said memory means to be read only by said decryption means.

Claim 69

A replaceable security module for storing a secret serial number and performing a decryption of a partially decrypted key and outputting a descrambling control signal, said replaceable security module comprising; connector means for connecting said replaceable security module to a decoder and through which a partially decrypted key is received from said encoder and descrambling control signal is transmitted to said decoder, memory means for storing at least a secret serial number, and decryption means, coupled to said connector means and said memory means for performing a decryption on said partially decrypted key and outputting a descrambling control signal.

Claim 70

A replaceable security module for storing a secret serial number and performing a decryption of a partially decrypted key and outputting a descrambling control signal, said replaceable security module comprising; connector means for connecting said replaceable security module to a decoder and through which a partially decrypted key is received from said encoder and descrambling control signal is transmitted to said decoder, memory means for storing at least a secret serial number, and decryption means, coupled to said connector means and said memory means for performing a decryption on said partially decrypted key and outputting a descrambling control signal.

Claim 71

The replaceable security module of claim 58, wherein said memory means further comprises: security means for allowing the contents of said memory means to be read only by said decryption means.