JPH05110558A - Cipher processor - Google Patents

Abstract

PURPOSE:To provide the cipher processor provided with a means for changing a part or the whole of a cypher/decypher algorithm, and a character changing/ converting table when a cipher is decyphered. CONSTITUTION:A part or the whole of a program for constituting a part or the whole of a processing means 1 for generating a cipher sentence by enciphering a ordinary sentence, or decyphering an enciphered ciphere sentence is stored in an EEPROM 3. Also, in the case a cipher is decyphered, a rewriting means 5 rewrites a part or the whole of the processing means 1 stored in the EEPROM 3 by a signal inputted through a communication means 9 from the outside, and deals with the decyphering of the cipher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryptographic processing device used in, for example, pay broadcasting.

[0002]

2. Description of the Related Art Conventionally, in pay broadcasting and the like, plaintext is encrypted according to an encryption algorithm, and the plaintext obtained by this encryption is transmitted, and at the time of reception, this plaintext is decrypted according to the decryption algorithm. I was trying to get various information.

An encryption / decryption algorithm used in a conventional encryption processing device will be described below with reference to FIG. In this conventional cryptographic processing device, for example, when decrypting a text, a ROM (Read Only) of the processing unit 101 is used.
According to the encryption / decryption algorithm stored in the Memory, the transliteration / substitution table stored in the ROM 103 is read, and the cipher is decrypted by referring to this transposition / substitution table. Therefore, if this transfer / substitution table can be changed, a different encryption algorithm can be used.

On the other hand, since most of this encryption processing is performed according to a preset program, these encryption / decryption algorithm and transliteration / substitution table are usually placed on a ROM that cannot be rewritten but read. Is.

[0005]

However, there is a possibility that these ciphers will be decrypted, and if an encryption / decryption algorithm and a transliteration / substitution table are provided on the ROM, rewriting will be possible when the cipher is decrypted. Since this cannot be done, the encryption / decryption algorithm and the transliteration / substitution table cannot be changed, and it cannot be dealt with.

The present invention has been made in view of the above problems, and even if the cipher is deciphered, the cipher that can be dealt with by changing part or all of the cipher / decryption algorithm and the transliteration / substitution table. An object is to provide a processing device.

[0007]

In order to achieve the above object, the present invention provides a processing means for encrypting a plaintext into a plaintext, or a culture means for recovering the encrypted plaintext, or a part of the processing means. Rewritable and non-volatile storage means for storing a part or all of the program forming the whole, and rewriting means for rewriting a part or all of the processing means stored in the storage means by a signal input from the outside. The gist is to have.

[0008]

The cryptographic processing device of the present invention can rewrite part or all of the program that constitutes part or all of the processing means for encrypting plaintext to make it plaintext, or recovering the encrypted plaintext. And is stored in a non-volatile storage means.

When the code is decrypted,
Since the storage means is rewritable, the rewriting means rewrites part or all of the processing means stored in the storage means by a signal input from the outside to deal with the decryption of the cipher.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining the configuration of a decoder to which the present invention is applied. In the first embodiment shown in FIG. 1, since the encryption and the decryption are almost the same, the case of decryption in which this proposal is most effectively used will be described as an example.

In FIG. 1, a plaintext is encrypted according to an encryption algorithm, a coded text obtained by this encryption is transmitted, and the received coded text is input to a processing means 1 and the processing means 1 The state in which the decrypted sentence is output according to the decryption algorithm is shown. This processing means 1 has a non-volatile rewritable memory 1a that stores a decoding algorithm, and this non-volatile rewritable memory is, for example, an EEPROM (Electrically).
Erasable Programmable ROM)
Is adopted. Further, the processing means 1 is connected to a non-volatile rewritable memory 3 for storing a transliteration / replacement table. The nonvolatile rewritable memory 3, like the processing means 1, employs, for example, an EEPROM as the memory.

The non-volatile rewritable memory 3 is connected to a rewriting means 5 including a decoding algorithm rewriting means 5B and a transposing / replacement table rewriting means 5A. The rewriting means 5 is rewritten by a rewriting command detecting means 11. When a command is detected, the decryption algorithm of the processing means 1 and the rewriting / rewriting table of the non-volatile rewritable memory 3 are rewritten.

The communication means 9 is provided separately from the decoder, for example, the new transposing / replacement table, the new decoding algorithm and the rewriting command stored in the storage means 7 installed in the broadcasting station, the rewriting means 5 and the rewriting command. Detecting means 11
Wireless communication is usually used, but it may be wired such as cable broadcasting, and it may be directly connected to a terminal provided for rewriting in the decoder. It may be.

Next, the operation of this embodiment will be described in accordance with the implicit sentence recovery process. In the normal state, the processing means 1
The ciphertext input to is decrypted according to the decryption algorithm stored in the non-volatile rewritable memory 1a and recovered, thereby performing the recovery operation. At this time, the decoding algorithm is executed by referring to the transliteration / substitution table stored in the non-volatile rewritable memory 3.

Further, when it is necessary to rewrite the decoding algorithm or the transliteration / replacement table by changing the broadcast format or deciphering the encryption, the storage is performed via the communication means 9 by wired or wireless communication. The new transliteration / replacement table, the new decoding algorithm and the rewriting command stored in the means 7 are transmitted to the rewriting means 5 and the rewriting command detecting means 11 of the decoder. This rewriting command is detected by the rewriting command detecting means 11, and the decoding algorithm rewriting means 5B and the transliteration / replacement table rewriting means 5A decode the algorithm and the new decoding algorithm of the transliteration / replacement table, and rewriting to the new transliteration / replacement table. It requires an action.

Therefore, when the rewriting command is detected by the rewriting command detecting means 11, this detection signal is input to the rewriting means 5 to request the rewriting operation, and the decoding algorithm rewriting means 5B and the transposing / rewriting table of the rewriting means 5 are requested. The rewriting means 5A rewrites the decoding algorithm stored in the non-volatile rewritable memory 1a of the processing means 1 and the transliteration / substitution table stored in the non-volatile rewritable memory 3 into a new decryption algorithm and a new transliteration / substitution table, respectively. Be done.

As described above, since the decoding algorithm and the transliteration / replacement table are both stored in the non-volatile rewritable memory, for example, the EEPROM, the decryption algorithm rewriting means 5B and the transposing / replacement table rewriting means 5A are included. The rewriting operation performed by the rewriting unit 5 can be appropriately rewritten as necessary. Further, the decryption algorithm rewriting means 5B and the transliteration / replacement table rewriting means 5A are provided with the new decryption algorithm and the new transliteration / replacement table stored in the storage means 7 by the communication means 9, so that it is necessary. Quick rewriting is possible.

Next, a second embodiment will be described with reference to FIG. Since the encryption and the decryption are almost the same in the second embodiment, the case of the decryption process in which this proposal is most effectively used will be described as an example. Although the decoding algorithm is not rewritten in FIG. 2 for the sake of understanding, the decoding algorithm can be rewritten by performing the same as in the first embodiment.

This second embodiment is a system with high security which is a further development of the first embodiment, and it has a processing means 21 for decoding and decoding the coded text according to a decoding algorithm and outputting the text. First non-volatile rewritable memory 23A for storing the transliteration / replacement table of No. 2 and second non-volatile rewritable memory 23 for storing the second transliteration / replacement table of
B, the transliteration / substitution table rewriting means 25, the new transposition / substitution table extraction means 27, and the rewriting command detection means 31.
And a table designating bit extracting means 33 and a changeover switch 35.

In the second embodiment, two types of transliteration / substitution tables are stored in the non-volatile rewritable memories 23A and 23B, that is, a first transliteration / substitution table and a second transposition / substitution table. Are stored respectively. In addition, the plaintext normally used in the system is input in the form of a packet, and this packet is encrypted so that it can be decrypted by the first transliteration / substitution table 23A. Further, each packet is provided with a table designation bit for selecting whether to use the first transliteration / substitution table 23A for decoding or the second transliteration / substitution table 23B for decoding. The bits are extracted by the table designation bit extracting means 33, and the switch 35 for selecting which of the first transposing / substitution table and the second transposing / substitution table is to be used is operated. .. As a result, the transliteration / substitution table data for decrypting the encryption applied to the packet is given to the decryption algorithm of the processing means 21.

Therefore, the first transfer / substitution table 23A
Packets that are encrypted so that they can be decrypted with are always sent, so it can be said that they are likely to be decrypted. Therefore, when the code is decrypted, it is necessary to change the encryption algorithm, so a packet for rewriting the transliteration / substitution table shown in FIG. 3 is added as a text.

This encrypted input packet includes an algorithm switching signal 41, a table designation bit 43, a transliteration / conversion character table alteration command 45, a first transliteration / conversion character table alteration data 47 and a second transliteration / conversion. It is composed of the character table change data 49. Of these, the transfer / conversion character table change command 45, the first transfer / conversion character table change data 47 and the second transfer / conversion character table change data 49 are The second transcribing / substitution table 23B used only when rewriting the transliteration / substitution table is encrypted.

Therefore, the cipher which is normally decrypted by the second transliteration / substitution table 23B is converted into the first transliteration / conversion character table change data 47 and the second transliteration / conversion character table change data 49. Based on the new first transliteration / substitution table 23Aa and the second transliteration / substitution table 23Ba, which cannot be solved while being rewritten, the decryption person must have performed the rewriting in the middle of the decryption. Without being able to know the contents of the first transliteration / conversion character table change data 47 and the second transliteration / conversion character table change data 49 newly transmitted this time, It is necessary to decipher a complex cipher in which the cipher decrypted by the second transliteration / substitution table 23B and the cipher decrypted by the first transliteration / substitution table 23A are switched in the middle, New first rolling character-substitution table 23 of
This makes it more difficult to decipher the cipher which is decrypted by Aa.

FIG. 4 shows a third embodiment in which the first embodiment shown in FIG. 1 or the second embodiment shown in FIG. 2 is arranged in parallel. That is, this third embodiment is shown in FIG.
In, the plaintext obtained by encrypting the plaintext according to the encryption algorithm is input to the first algorithm or the second algorithm via the algorithm switching detection means 61, and this plaintext is stored in the nonvolatile rewritable memory. The decoding is performed according to the decoding algorithm described above, and the restored text obtained by this decoding is output via the changeover switch 67.

Specifically, the first algorithm 6 is initially used.
When it is assumed that the ciphertext is sent by 3, the algorithm switching signal detecting means 61 detects the algorithm switching signal on the communication path which is transmitted when it is found that the first algorithm 63 has been decrypted, The system switches the algorithm switch signal to use the second algorithm 65. In the meantime, as in the first embodiment shown in FIG. 1 or the second embodiment shown in FIG. 2, the algorithm rewrite command is sent to the encryption algorithm to be rewritten, and this algorithm (the first algorithm 63 in this case) is sent. change. Once again it is found that the second algorithm 65 has been decrypted, the algorithm switch signal is changed to use the new first algorithm 63a rewritten while using the second algorithm 65 again. good.

In the present embodiment, these operations are repeated every time it is determined that the code has been decrypted, so that the system is continuously operated, and at the time when it is determined that the code has been decrypted, no hardware is required. It is possible to build a cryptographic system with high security without modification.

[0027]

As described above, according to the present invention,
Even if the existing cipher is broken, it can be changed to the new cipher, so that the security of the system can always be maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment according to the present invention.

FIG. 2 is a block diagram showing a configuration of a second exemplary embodiment according to the present invention.

FIG. 3 is a diagram showing a configuration of a transliteration / substitution table used in the second embodiment shown in FIG.

FIG. 4 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing means 3 Non-volatile rewritable memory 5A Transliteration / replacement table rewriting means 5B Decoding algorithm rewriting means 7 Storage means 9 Communication means 11 Rewriting command detecting means 21 Processing means 23A First non-volatile rewritable memory 23B Second non-volatile Rewritable memory 25 Transliteration / substitution table rewriting means 27 New transposition / substitution table extraction means 31 Rewriting command detection means 33 Table designation bit extraction means 35 Changeover switch 41 Algorithm switching signal 43 Table designation bit 45 Transliteration / conversion character table Change command 47 First transliteration / conversion character table alteration data 49 Second transliteration / conversion character table alteration data 61 Algorithm switching detection means 63 First algorithm 65 Second algorithm 67 Changeover switch

Claims (1)

[Claims] 1. A processing unit for encrypting a plaintext into a plaintext, or for recovering the encrypted plaintext, and a rewriting for storing a part or all of a program constituting a part or all of the processing unit. A cryptographic processing device comprising: a possible and non-volatile storage means and a rewriting means for rewriting a part or all of the processing means stored in the storage means by a signal input from the outside.