JPH0468836B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an encryption key distribution method for descrambling broadcast program data scrambled by a key on the transmitting side on the receiving side.

[Prior Art] FIG. 2 shows a conventional scrambling encryption key distribution system. In FIG. 2, the left side shows the transmitting side, and the right side shows the receiving side.

There are three types of encryption keys on the sending side: a scramble key Ks, a work key Kw, and a unique key Kmp. The program data BD is broadcast program data common to all receivers, and is scrambled with a scramble key Ks in the scrambler 101 and converted into a signal.
Converted to eBD. BJ is program information attached to a program common to recipients, and this program information BJ is composed of viewing permission conditions (eg, program price, viewing condition code, etc.), scramble key Ks, and the like. The program information BJ is encrypted by the work key Kw in the encoder 102 and converted into the signal eBJ. The scramble key Ks is a short-cycle key that is normally updated every about 1 second. Also, KJp in the individual information KJ group
is individual information unique to a specific recipient p (for example, Mr. In the device 103, the signal is encrypted using the unique key Kmp of the receiver p and converted into a signal eKJp. The above-mentioned work key Kw is a long-period key that is usually updated every about one month. In Figure 2, the individual information KJ group consists of KJ1, KJ2, ...KJn (n
is the number of recipients), and KJp represents one of the KJ groups. All of the KJ groups are each encrypted by the encoder 103 with the corresponding unique keys of the unique key Km group to become eKJ groups. The receiver-specific key group includes keys Km1, Km2, ..., Kmp, which each receiver owns one key group.
..., Kmn.

A large number of eKJs of the above-mentioned signals eBD and eBJ are combined by a combiner 104 and then delivered to each recipient.

On the other hand, on the receiving side, the signals eBD, eBJ and a large number of eKJs delivered to each receiver are sent to a separator 10.
5, and only the signals eBD, eBJ and the information addressed to itself eKJp are extracted. First, eKJp is decrypted into the original KJp by the decryptor 106 using the unique key kmp of the recipient p. Next, eBJ, in the decoder 107,
It is decrypted to the original BJ using the work key Kw that is common to the recipients and is included in KJp. Finally, the first half of K.J.
The switching device 109 becomes conductive only when the comparing and matching device 108 determines that the contract terms included in the eBD match the viewing permission conditions included in the BJ, and the descrambler 110 determines that the eBD is included in the BJ. The data is descrambled using the scramble key provided. In this way, the original program data BD is taken out and viewed on the recipient side.

[Problems to be solved by the invention] In the conventional key distribution method described above, if the number of recipients is 10 million, for example, the ability to distribute work keys Kw through one transmission path is 1 million per hour. Even if the work key is a person, the work key is encrypted with each recipient's unique key and delivered individually to each recipient, so it takes at least 10 hours to deliver the work key Kw to all recipients. Requires. In addition, if the recipient cannot always wait for reception or if the work key is sent several times in consideration of errors occurring in the transmission path, the delivery time of the work key Kw may take several tens of hours or more. Become. In this way, with conventional key distribution methods, when there are many recipients, the time required to send the work key becomes a problem, and it is not possible to deliver the work key Kw to all recipients in a short time using only one transmission path. It has the following drawbacks.

An object of the present invention is to provide an encryption key distribution system that can distribute a work key Kw in a short time even if there are many recipients.

[Means for solving the problem] In the encryption key distribution method according to the present invention, the scramble key is extracted on the receiving side under the condition that the contract conditions of individual information and the viewing permission conditions of program information match. Taking this into consideration, the unique key consists of a key common to all recipients and a different key for each recipient, and the work key is encrypted with a key common to all recipients and given to all recipients, and individual information other than the work key is is configured to be encrypted and transmitted using a different key for each recipient.

[Example] Examples of the present invention will be described below with reference to additional drawings.

FIG. 1 is a block diagram showing an encryption key distribution system according to the present invention. In FIG. 1, the left side shows a transmitting side device, and the right side shows a receiving side device. In Figure 1,
Since the basic configuration is the same as the conventional one shown in FIG. 2, the same elements shown in FIG. 1 and FIG. That is, 101 is a scrambler that scrambles program data BD, 102 is an encoder that encodes program information BJ, 103 is an encoder that encodes individual information, 104 is a synthesizer, 105 is a separator, and 106
107 is a decoder that decodes individual information; 107 is a decoder that decodes program information; 108 is a comparison/verification device; 109
110 is a switch, and 110 is a descrambler. The functions of each of the above components are as explained in the prior art section.

Next, characteristic parts of the present invention will be explained. The group of unique keys Km on the sending side includes unique keys Km1, Km2, . . . Kmp, . In the above, n is an integer representing the number of recipients, and p is a code representing an arbitrary recipient. Encryptor 103
encrypts the individual information KJp included in the individual information KJ group, but in this case, the common individual information KJO including the work key Kw and the other individual information KJp
and separately encrypted. That is, the encoder 103
Common individual information KJO including work key Kw in
is encrypted with the key KmO and exchanged into the signal eKJO,
Individual information KJp that differs for each other patient is encrypted using a key Kmp that differs for each recipient, and the signal eKJp
is converted to

On the other hand, on the receiving side, the decoder 106 decrypts the transmitted signals eKJO and eKJp using a common key KmO provided to each receiver and a different key Kmp for each receiver. and KJO
Take out. And individual information KJO work key Kw
The decoder 107 extracts the program information BJ using
Individual information KJp and program information BJ are compared and verified by the comparison unit 108.
are compared, and only when the contract condition and the viewing permission condition match, the switch 109 is made conductive and the scrambler key Ks is output.

In the above example, a key common to the recipients
Although KmO is common to all recipients, it can be configured as multiple keys by dividing all recipients into multiple blocks and providing a different key for each block. In this way, several or more keys common to recipients can be used if necessary.

[Effects of the Invention] As is clear from the above explanation, according to the present invention,
By preparing a common key for recipients in the unique key and encrypting the work key with this key, the work key can be instantly delivered to all recipients, significantly reducing the delivery time of long-cycle work keys. It can be shortened to Furthermore, even if the recipient has a short-term contract of one month, the work key can be changed at any time as needed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the encryption key distribution method according to the present invention, and FIG. 2 is a block diagram for explaining the conventional encryption key distribution method. [Explanation of codes] 101...Scrambler, 10
2,103...Encryptor, 104...Synthesizer, 10
5...Separator.

Claims (1)

[Claims] 1. A system that uses a scramble key to scramble program data, a work key to encrypt program information including this scramble key, and a unique key to encrypt individual information including this work key. In an encryption key distribution method in which the encrypted scramble key and work key are transmitted to each recipient, the unique key is a common key for the recipients and a key different for each recipient. On the sending side, the work key is encrypted with a key common to the recipients, and the individual information other than the work key is encrypted with a key that differs for each recipient, while the In this case, the unique key includes a key common to the receivers and a different key for each receiver, and the work key is extracted by decrypting the individual information with the key common to the receivers, and the individual information is The recipient's individual information is extracted by decrypting it with a different key for each recipient, and the viewing permission conditions in the program information decrypted with the extracted work key and the recipient's individual information are extracted. An encryption key distribution system characterized in that a scramble key extracted using the work key is given to a descrambler when reception contract conditions are met.