JPH10293725A - External storage device, ciphering unit device, decoding unit device, ciphering system, decoding system, ciphering method and decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unauthorized copying by a third person by ciphering a data ciphering key by an intrinsic secret key stored inside an external storage device, recording it in a recording medium along with data ciphered by the data ciphering key and not preserving the data ciphering key. SOLUTION: Along with the data ciphered by the data ciphering key, the data ciphering key is ciphered by the intrinsic secret key stored inside this external storage device (IC card) and recorded in the recording medium and the data ciphering key is not preserved. That is, in this system, at the time of ciphering one set of the data, the data ciphering key Sdk used for the ciphering of the data is generated and the Sdk ciphered by an intrinsic key Kic stored in the IC card 101 or the like and the data ciphered by the Sdk are recorded in the recording medium 121. At the time of reproduction, the data ciphering key read from the recording medium 121 is decoded by using the intrinsic key Kic and the ciphered data are decoded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external system for a system for communicating digitalized data such as documents, voices, images and programs via a network, or a system for recording and storing the digital data and for reading out the digital data. The present invention relates to a storage device, an encryption unit device, a decryption unit device, an encryption system, a decryption system, an encryption method, and a decryption method.

[0002]

2. Description of the Related Art At present, computers have become widespread, and it has become common practice to digitize and process information in various fields, or to digitize and save information in a recording device. In addition, network environments are becoming more and more common, and information is digitized for communication. In addition to document information,
The technology for electronically handling data such as voice and images is also rapidly advancing.

[0003] By the way, electronically handled information includes, of course, information that requires confidentiality, such as corporate secrets and personal information. It also includes information that requires careful handling, such as information related to copyright.

[0004] Therefore, a technique is often used in which information is encrypted when it is handled electronically so that only authorized persons can decrypt it. For example, in a cryptographic system in which data is encrypted and stored in a recording medium, and encrypted data is read from the recording medium and decrypted to extract the original data, a secret key used for encryption and decryption is determined in advance, and the secret key is determined. Saving and reading are performed using the key. According to this system, only a person who can use the secret key can decrypt the stored encrypted data, and a third party who cannot use the secret key is encrypted unless the secret key is decrypted. Data cannot be deciphered illegally.

[0005]

However, in the above system, if the secret key is decrypted by an unauthorized attack by a third party, not only all the encrypted data is decrypted, but also the data obtained by the decryption. (Plain data) can be freely copied.

Further, even if the secret key is not decrypted, if the same secret key is incorporated in another encryption system, the pirated copy can be easily created by copying the encrypted data as it is. I can do it.

Further, when it is discovered that the secret key has been revealed, it is necessary to update the secret key of the corresponding encryption system, which is not only complicated, but also after the secret key is updated, the secret key is revealed. In a system that takes an update form that cannot be used for decryption, after the private key is updated, the data encrypted with the exposed private key can no longer be decrypted, and the original There is a problem that the contents cannot be obtained.

The present invention has been made in view of the above circumstances, and has an external storage device, an encryption unit device, a decryption unit device, an encryption system, which can prevent unauthorized copying by a third party. It is an object to provide a decryption system, an encryption method, and a decryption method.

Further, the present invention provides an external storage device, an encryption unit device, a decryption unit device, which makes it difficult for a third party to obtain key information or decrypt encrypted data.
It is an object to provide an encryption system, a decryption system, an encryption method, and a decryption method.

Further, the present invention provides an external storage device, an encryption unit device, a decryption unit device, an encryption system, a decryption system, an encryption method, and a decryption method which do not require a key information update procedure. The purpose is to:

[0011]

According to the present invention, there is provided a computer system, comprising:
Before recording data (digitized data; for example, documents, voices, images, programs, etc.) input without passing through the U bus with a predetermined data encryption key, the data is encrypted with a predetermined data encryption key. An external storage device having a processing function connected to the CPU bus of the computer and used for a device for encrypting the data encryption key with a predetermined secret key before recording it on the recording medium (for example, Means for recording a secret key unique to the own device in a form concealed from the outside, and the unique secret key to the encrypting device via a CPU bus of the computer. Means for securely transmitting the predetermined secret key without being obtained from outside.

According to the present invention, a data encryption key read from a predetermined recording medium and encrypted with a predetermined secret key given via a CPU bus of a computer is decrypted, and the obtained data encryption key is decrypted. For decrypting data read from the recording medium and encrypted with a predetermined data encryption key given through the CPU bus using the CPU of the computer.
An external storage device having a processing function used by being connected to a bus, means for recording a secret key unique to the device in a form concealed from the outside, and the CPU via the CPU bus of the computer. Means for securely transmitting the unique secret key to the decrypting device as the predetermined secret key without being obtained from outside.

The present invention relates to an encryption unit for encrypting data input without passing through a CPU bus of a computer before recording the data on a predetermined recording medium. Means for securely receiving a private key unique to the external storage device recorded in the external storage device in a form concealed from the outside without being obtained from the outside, and data encryption Means for securely receiving the generated data encryption key from the key generation device via the CPU bus without being obtained from the outside, and the data received using the received unique secret key. It is characterized by comprising means for encrypting an encryption key, and means for encrypting the data to be encrypted using the received data encryption key.

The present invention relates to a decryption unit for use in connection with a CPU bus of a computer for decrypting encrypted data recorded on a predetermined recording medium. Means for securely receiving, via the CPU bus, a private key unique to the external storage device recorded in the external storage device in a form concealed from the outside without being obtained from the outside; Decrypting the data encryption key read from the recording medium and encrypted with the unique secret key given through the CPU bus, using the unique secret key as a decryption key, Means for determining, and using the determined data encryption key as a decryption key, the CPU read from the recording medium.
Means for decrypting data encrypted with a data encryption key given via a bus.

The present invention relates to a decryption unit device which is used by being connected to a CPU bus of a computer for decrypting encrypted data recorded on a predetermined recording medium. An encryption unit device that encrypts input data generates a data encryption key used for encrypting data to be encrypted, and sends the data encryption key to the encryption unit device via the CPU bus. Means for securely transmitting the key without being obtained from the outside;
Via a CPU bus from a predetermined external storage device, a secret key unique to the external storage device, which is recorded in the external storage device in a confidential form from the outside, can be securely obtained without being obtained from outside. Means for receiving, using the received unique secret key as a decryption key, decrypting a data encryption key read from the recording medium and encrypted with the unique secret key given via the CPU bus. Means for obtaining a data encryption key, and using the obtained data encryption key as a decryption key to read out the C
Means for decrypting data encrypted with the data encryption key given via the PU bus.

Preferably, after performing a predetermined conversion process on the original data obtained by decrypting the encrypted data read from the recording medium, the data is output to the outside without passing through the CPU bus of the computer. May be further provided.

The present invention uses an external storage device having a processing function connected to a CPU bus of a computer, a device for generating a data encryption key, and an encryption unit device, and receives input from outside without passing through the CPU bus. An encryption system for encrypting the data before recording it on a predetermined recording medium,
The external storage device is configured to record a secret key unique to the device in a form concealed from the outside, and the encryption unit device obtains the unique secret key from the outside via the CPU bus. Means for generating a data encryption key, wherein the device for generating the data encryption key is a device for generating a data encryption key used for encrypting data to be encrypted by the encryption unit device. Means and the C
Means for securely transmitting the data encryption key to the encryption unit device via a PU bus without being obtained from the outside, the encryption unit device transmits the CPU bus from the external storage device to the external device. Means for securely receiving the unique private key without being obtained from the outside via an external device, and a device for generating the data encryption key,
Means for securely receiving the data encryption key via a PU bus without being obtained from the outside, and means for encrypting the received data encryption key using the received unique secret key And means for encrypting the data to be encrypted using the received data encryption key.

Preferably, the means for transmitting and the means for receiving are respectively C
A means for sharing a predetermined temporary key without being obtained from the outside by a predetermined key sharing procedure cooperatively performed by exchanging information via the PU bus,
The means for transmitting includes means for decrypting the generated data encryption key with the shared temporary key and outputting the decrypted data, and the means for receiving is decrypted with the provided temporary key. A means for encrypting the data encryption key with the shared temporary key may be provided.

The present invention relates to a decryption system for decrypting encrypted data recorded on a predetermined recording medium using an external storage device having a processing function connected to a CPU bus of a computer and a decryption unit device. The external storage device includes means for recording a secret key unique to the own device in a form concealed from the outside, and externally storing the unique secret key in the decryption unit device via the CPU bus. Means for transmitting the message safely without being obtained from the external storage device.
Means for securely receiving the unique secret key via a bus without being acquired from the outside, and the received unique secret key as a decryption key, read from the recording medium and read via the CPU bus. Means for decrypting a data encryption key encrypted with a given unique secret key to obtain a data encryption key; and reading the data encryption key from the recording medium as a decryption key. Served CP
Means for decrypting the data encrypted with the data encryption key given via the U bus.

Preferably, the means for transmitting and the means for receiving are respectively C
A means for sharing a predetermined temporary key without being obtained from the outside by a predetermined key sharing procedure cooperatively performed by exchanging information via the PU bus,
The means for transmitting includes means for encrypting the generated data encryption key with the shared temporary key and outputting the encrypted data, and the means for receiving is decrypted with the provided temporary key. A means for decrypting the data encryption key with the shared temporary key may be provided.

Preferably, after performing a predetermined conversion process on the original data obtained by decrypting the encrypted data read from the recording medium, the data is output to the outside without passing through a CPU bus of the computer. May be further provided.

According to the present invention, an external storage device having a processing function connected to a CPU bus of a computer, a device for generating a data encryption key, and an encryption unit device are externally input without passing through the CPU bus. An encryption method for encrypting the encrypted data before recording it on a predetermined recording medium, wherein the encryption method encrypts the encrypted data from the external storage device to the encryption unit device via the CPU bus in the external storage device from outside. A secret key unique to the external storage device recorded in a written form is securely transmitted without being obtained from the outside, and the encryption unit is transmitted from the device for generating the data encryption key via the CPU bus. The device securely transmits the data encryption key generated by the data encryption key without being acquired from the outside, and the encryption unit device receives the unique secret received by the encryption unit device. Encrypts the data encryption key received using, characterized by encrypting the data to be the encryption target using the data encryption key received.

The present invention relates to a decryption method for decrypting encrypted data recorded on a predetermined recording medium using an external storage device having a processing function connected to a CPU bus of a computer and a decryption unit device. And from the external storage device to the decoding unit device via the CPU bus,
A secret key unique to the external storage device recorded in a form concealed from the outside in the external storage device, and safely transmitted without being acquired from the outside, and received by the decryption unit device, Using the unique secret key as a decryption key,
The data encryption key read from the recording medium and encrypted with the unique secret key given via the CPU bus is decrypted, a data encryption key is obtained, and the obtained data encryption key is obtained. As a decryption key, data read from the recording medium and encrypted with a data encryption key given via the CPU bus is decrypted.

According to the present invention, a data encryption key is generated each time, data is encrypted and recorded on a recording medium, and the data encryption key is encrypted with a unique secret key stored in an external storage device. By recording the data on a recording medium, the data cannot be decrypted without using an external storage device that stores the unique secret key used for the encryption. For this reason, even if a copy of the recording medium is made and distributed by directly recording it on another recording medium from the CPU bus, others cannot decrypt it (cannot be decrypted with another external storage device). ).

According to the present invention, the data encryption key and the unique secret key are shared between the devices via the CPU bus, for example, by encrypting using a shared temporary key. Even if the information flowing on the CPU bus is recorded,
Since this cannot be used later (it cannot be decrypted because the temporary key is different), it becomes meaningless to record information from the CPU bus.

According to the present invention, the data encryption key itself for encrypting the data and the temporary key used to share the data encryption key change each time, so that the third party can decrypt the code. It is extremely difficult to do.

Therefore, according to the present invention, unauthorized copying by a third party can be prevented. As a result, creation of a pirated copy or the like can be prevented beforehand, and copyright can be protected effectively. Further, according to the present invention, the procedure for updating the key information becomes unnecessary.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, a system in which data is encrypted and recorded on a recording medium, and encrypted data is read and decrypted from the recording medium will be described as an example.

In this embodiment, the encryption operation is performed by Ey
Expressed as (x). Here, x is data to be encrypted, and y is an encryption key used for encryption. Also, the decoding operation is represented by Dy (z). Here, z is data to be decrypted, and y is a decryption key used for decryption.

In the present embodiment, there is a case where certain data is first decrypted, and then the decrypted data is returned to the original data after being encrypted. This is based on the fact that, due to the nature of encryption, data decryption has the same effect as encryption. In other words, in order to restore the decrypted data, the key used for decryption must be known, and if the key is known, the decrypted data is encrypted to obtain the first decrypted data . This operation is represented by Ex (Dx (y)) = y, where x is the encryption key and y is the data.

The system according to the present embodiment is connected to a CPU bus of a CPU (not shown) provided in a computer (hereinafter, a PC) such as a personal computer. Is realized. In the present embodiment, data input / output is performed through, for example, an I / O port or the like other than the CPU bus, but is used for data transfer between a disk drive device (not shown) and the unit and between units. Uses a CPU bus. Therefore, data flowing on the CPU bus is encrypted (or decrypted prior to encryption).

According to the present embodiment, when a set of data is encrypted, a data encryption key Sdk used for encrypting the data is generated and stored in a recording medium such as an IC card. Sdk and S encrypted with the unique key Kic
The data encrypted with dk is recorded, and the unique key K
The data encryption key read from the recording medium is decrypted using ic, and the encrypted data recorded on the recording medium is decrypted using this.

In the first embodiment, one example of sharing a key between an IC card and the like via a CPU and a unit, and between the units, and in the second embodiment, an example of sharing a key between the IC card and the like via a CPU Another example of sharing a key between units is shown.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a block diagram showing the composition of the system used for data encryption concerning an embodiment. The key sharing circuit 3 of FIG.
FIG. 2 shows an example of the internal configuration of Oa and 30b, and FIG. 3 shows an example of the internal configuration of the key sharing circuits 30b and 30c in FIG. FIG. 4 shows an encryption procedure of the present system, and FIG. 5 shows an example of a key sharing procedure.

FIG. 6 is a block diagram showing the configuration of a system used for decoding data according to the first embodiment of the present invention. FIG. 7 shows an example of the internal configuration of the key sharing circuits 30a and 30c in FIG. FIG. 8 shows a procedure for decryption of the present system, and FIG. 5 shows an example of a key sharing procedure.

As shown in FIG. 1, the system according to the present embodiment includes an external storage device (for example, an IC card; hereinafter, referred to as an IC card) 101 having a processing function, an encryption unit 102, and a decryption unit 104. ing. The IC card 101, the encryption unit 102, and the decryption unit 104 are connected to the CPU bus 103 of the PC. Note that the IC card 100 is connected only when used,
Otherwise, it is desirable to remove it and keep it.

A disk drive (not shown) is connected to the CPU bus 103, and the disk drive performs reading and writing on the recording medium 121. As shown in FIG. 1 and FIG.
Has a decryption circuit 115 as a part used for encryption, has an encryption circuit 210b as a part used for decryption, and has a key sharing circuit 30c as a part used for both encryption and decryption. The above components are formed as one independent IC chip and are sealed in the IC card.

The IC card 101 has a portion used for encryption (FIG. 1) and a portion used for decryption (FIG. 6).
May be separated into two and configured as two IC cards.

The encryption unit 102 includes the key sharing circuit 30
b, encryption circuits 117b to 117e. The encryption unit 102 is formed as one independent IC chip.

The decryption unit 104 includes a data encryption key generation circuit 105 and a decryption circuit 110b as parts used for encryption, and decryption circuits 207b to 207d as parts used for decryption. A key sharing circuit 30a is provided as a part used for both. The decoding unit 104 shall be formed as one independent IC chip.

The decryption unit 104 is divided into two parts, a part used for encryption (FIG. 1) and a part used for decryption (FIG. 6). ).

The overall control is performed by a control unit (not shown). The control unit can be realized, for example, by executing a program by the CPU of the PC. The data Data is input data to be encrypted and recorded, and is, for example, multimedia data such as video, audio, and text input from an I / O port of a PC.

Sdk is a data encryption key (common key in the common key cryptosystem) used for encrypting and decrypting data. In the present embodiment, the Sdk is generated (changed) for each set of data (for example, for each title). The Sdk may be generated (changed) for each disk, may be generated (changed) for each side of the disk or for each set of a plurality of disks, or may be generated for each group. The data may be generated (changed) for each subdivided portion (for example, for each chapter or for each song).

Kic is recorded in a secret area of the IC card 101 which cannot be taken out by the user.
This is a secret key (common key in the common key cryptosystem) unique to the IC card 101. This secret key Kic is different for each IC card.

Skf, Sks, and Skr correspond to the CPU bus 1
This is a temporary key (common key in a common key cryptosystem) to be converted each time the information is decrypted (decryption performed prior to encryption) when the information is passed on the information 03.

The data encryption key generation circuit 105 generates a data encryption key Sdk. Data encryption key generation circuit 105
May be constituted by a random number generator for the key length, for example. In generating a random number, time information from a clock (not shown) may be used. In addition,
When a key is generated with a random number in which all bits may be 0 or 1, it is necessary to perform a check process or the like so that all bits do not become 0 or 1.

The key sharing circuits 30a, 30b, and 30b have at least logically the same configuration, exchange information with the counterpart circuit by a procedure described later, and use the same temporary key (bus key) (Skf , Sks, Skr) are generated and shared. In the present embodiment, the decryption unit 10
4 and the encryption unit 102 are the key sharing circuits 30a and 30b.
, The same temporary key Skf is securely shared without being known from outside, and the encryption unit 102 and IC
The card 101 uses the key sharing circuits 30b and 30c to securely share the same temporary key Sks without being known from the outside, and similarly, the decryption unit 104 and the I
The C card 101 safely shares the same temporary key Skr using the key sharing circuits 30a and 30c. Key sharing circuit 30
It is assumed that a, 30b, and 30b are built in the IC chip so that the logic inside is not analyzed from outside.

In this embodiment, the encryption unit 10
2, one key sharing circuit 30b is provided. Instead, two key sharing circuits corresponding to the key sharing circuits 30a and 30c in the encryption unit 102 are provided. The same configuration as the key sharing circuit 30b) may be provided.

The recording medium 121 is for recording the input data from the encrypted I / O port. For example, a hard disk, an MO, an FD, a once-writable CD, a DVD-RAM, or the like is used. Can be considered.

In some cases, the disk drive device includes a modulation / demodulation / error correction circuit that performs a modulation and error correction circuit during recording and performs a demodulation and error correction circuit during reproduction.

In this embodiment, the decoding unit 1
04 is provided with a D / A conversion circuit for converting digital data Data into analog data.
It is assumed that data converted from analog is output from 04. When the digital data Data is to be decoded, a decoding circuit for decoding the digital data is D / A.
It shall be provided before the conversion circuit. For example, when the digital data Data is image data compressed by the MPEG system, an MPEG decoding circuit is provided. Also, a plurality of types of decoding circuits are provided so as to be able to output either data compressed or the like by various methods or data that does not need to be decoded, and these are switched appropriately and used, or these are not used. It is also possible. The output from the decoding unit 104 is displayed on a display as an image, for example.

First, the procedure at the time of encryption will be described with reference to FIGS. Note that C in FIG.
The PU corresponds to a control unit when implemented by a program, and here indicates that the CPU, that is, the control unit, mediates the procedure. Note that information may be directly exchanged between units without mediation of the control unit.

First, the IC card 101 is inserted into a card slot or the like (not shown) of the PC. If the recording medium 121 is a removable medium, it is set in a disk drive (not shown).

In step S11, the decoding unit 10
4 and the encryption unit 102 share a temporary key Skf by a key sharing procedure. Further, the temporary key Sk is shared between the encryption unit 102 and the IC card 101 by a key sharing procedure.
Share s.

Here, "Nikkei Electronics N
o. 676 pp. 13-14 1996.11.1.
8 "shall be applied. First, the configuration of the key sharing circuits 30a, 30b, and 30c shown in FIGS. 1 and 2 used for the key sharing procedure in the present embodiment will be described.

The key sharing circuit 30a includes a challenge key generation circuit 31a, an authentication key generation circuit 33a, a comparison circuit 35a, and a bus key generation circuit 37a. Similarly, the key sharing circuit 30b includes a challenge key generation circuit 31b, an authentication key generation circuit 33b, a comparison circuit 35b, and a bus key generation circuit 37b. Similarly, the key sharing circuit 30c includes a challenge key generation circuit 31c, an authentication key generation circuit 33c, and a comparison circuit 35
c, a bus key generation circuit 37c.

Challenge key generation circuits 31a, 31b, 3
1c generates a challenge key that changes each time it is generated using, for example, a random number generation algorithm. The authentication key generation circuits 33a, 33b, and 33c generate an authentication key from a challenge key using, for example, a one-way function.

The comparison circuits 35b and 35c compare whether or not the two authentication keys match. Bus key generation circuits 37a, 3
7b and 37c generate a bus key, that is, a temporary key, from two authentication keys using, for example, a one-way function.

Authentication key generation circuit 33a and authentication key generation circuit 3
3b and the authentication key generation circuit 33c generate the same authentication key for the same challenge key by using, for example, the same algorithm.

Bus key generation circuit 37a and bus key generation circuit 3
7b and the bus key generation circuit 37c generate the same bus key from the same two authentication keys, for example, by using the same algorithm.

Next, a key sharing procedure performed between the decryption unit 104 and the encryption unit 102 will be described with reference to FIGS. First, in phase 1 of the key sharing procedure, in the decryption unit 104, the challenge key (Challen) is generated by the challenge key generation circuit 31a.
ge Key) 1 is generated, and this is
Tell 2 too. Next, each of the authentication key generation circuit 33a of the decryption unit 104 and the authentication key generation circuit 33b of the encryption unit 102 generates an authentication key 1 (Key1) based on the challenge key 1, The generated authentication key 1 is transferred from 102 to the decryption unit 104. Then, in the decoding unit 104, the comparison circuit 35
a, the decryption unit 104 and the encryption unit 10
The two authentication keys 1 generated in each of the two are compared.
If they match, the next phase 2 is started. If they do not match, the process ends abnormally.

Next, in the phase 2, the encryption unit 1
At 02, a challenge key (Challenge Key) 2 is generated by the challenge key generation circuit 31b, and this is also transmitted to the decryption unit 104. Next, the authentication key generation circuit 33b of the encryption unit 118 and the decryption unit 1
Each of the authentication key generation circuits 33a of 04 generates an authentication key 2 (Key2) based on the challenge key 2 and transfers the generated authentication key 2 from the decryption unit 104 to the encryption unit 102. Then, the encryption unit 102
The comparison circuit 35b compares the two authentication keys 2 generated by the encryption unit 102 and the decryption unit 104, respectively. If they match, the next phase 3 is started. If they do not match, the process ends abnormally.

Then, in phase 3, the bus key generation circuit 37a of the decryption unit 104 and the encryption unit 102
The bus key generation circuit 37b generates a bus key (BUS Key), that is, a temporary key Skf, based on the authentication key 1 and the authentication key 2.

As a result, the temporary key Skf is safely shared between the decryption unit 104 and the encryption unit 102. Next, a key sharing procedure performed between the encryption unit 102 and the IC card 101 will be described with reference to FIGS.

First, in phase 1 of the key sharing procedure, a challenge key (Challenge Key) 1 is generated by the challenge key generation circuit 31b in the encryption unit 102 and transmitted to the IC card 101. Next, the authentication key generation circuit 33b of the encryption unit 102 and the authentication key generation circuit 33c of the IC card 101 respectively generate an authentication key 1 (Key 1) based on the challenge key 1, and The generated authentication key 1 is transferred to the encryption unit 102. Then, the encryption unit 102
The comparison circuit 35b compares the two authentication keys 1 generated by the encryption unit 102 and the IC card 101, respectively. If they match, the next phase 2 is started. If they do not match, the process ends abnormally.

Next, in the phase 2, the IC card 101
, A challenge key (Challenge Key) 2 is generated by the challenge key generation circuit 31c and transmitted to the encryption unit 102. Next, the IC card 10
1 generates an authentication key 2 (Key2) based on the challenge key 2 in each of the authentication key generation circuit 33c and the authentication key generation circuit 33b in the encryption unit 102. The generated authentication key 2 is transferred. Then, in the IC card 101, the comparison circuit 3
5c, the IC card 101 and the encryption unit 102
Are compared with each other for the two authentication keys 2 generated. If they match, the next phase 3 is started. If they do not match, the process ends abnormally.

In the phase 3, the bus key generation circuit 37b of the encryption unit 102 and the bus key generation circuit 37c of the IC card 101 respectively use the bus key (BUS Key) based on the authentication key 1 and the authentication key 2. ), That is, a temporary key Sks is generated.

Thus, the encryption unit 102 and I
The temporary key Sks is safely shared with the C card 101. In step S12, a unique secret key Kic is transmitted from the IC card 101 to the encryption unit 102 using the shared temporary key Sks.
That is, first, in the IC card 101, the decryption circuit 1
In step 15, the secret key Kic unique to the IC card 101 is decrypted by Sks to obtain DSks (Kic). Next, the CP is sent from the IC card 101 to the encryption unit 102.
DSks (Kic) is sent through the U bus 103. Then, in the encryption unit 102, the encryption circuit 117d
Encrypts DSks (Kic) with Sks,
get ic.

In step S13, the decoding unit 10
At 4, the data encryption key generation circuit 105 generates a data encryption key Sdk for encrypting the input data. In step S14, the data encryption key Sdk is transmitted from the decryption unit 104 to the encryption unit 102 using the shared temporary key Skf. That is, first, in the decoding unit 104, Skf
By decoding dk, DSkf (Sdk) is obtained. Next, the CPU is sent from the decryption unit 104 to the encryption unit 102.
DSkf (Sdk) is sent through the bus 103. Then, in the encryption unit 102, the DSkf (Sdk) is encrypted with Skf by the encryption circuit 117b, and Sd
Get k.

In step S15, the encryption unit 10
At 2, the Sdk is encrypted by the encryption circuit 117e using Kic as an encryption key to obtain EKic (Sdk). Then, EKic (Sdk) is recorded on the recording medium 121.

In step S16, the encryption unit 10
In step 2, the input data Data is encrypted by the encryption circuit 117c using Sdk as an encryption key,
(Data) is obtained. Then, the ESdk (Data) is recorded on the recording medium 121.

Note that a plurality of EKic
When (Sdk) is stored, EKic (Sdk) and E
Sdk (Data) are stored in association with each other. Next, a procedure for decoding will be described with reference to FIGS.

First, the IC card 101 is inserted into a card slot or the like (not shown) of the PC. If the recording medium 127 is a removable medium, it is set in a disk drive (not shown).

In step S21, the temporary key Skr is shared between the decryption unit 104 and the IC card 101 by a key sharing procedure, as in step S11. First, in phase 1 of the key sharing procedure, the decryption unit 10
At 4, the challenge key (Challenge Key) 1 is generated by the challenge key generation circuit 31a and transmitted to the IC card 101. Next, decoding unit 1
The authentication key generation circuit 33a of the IC card 101 and the authentication key generation circuit 33c of the IC card 101 generate an authentication key 1 (Key 1) based on the challenge key 1, respectively.
01 to the decryption unit 104. Then, in the decryption unit 104, the decryption unit 104 and the IC card 10 are
The two authentication keys 1 generated by each of the authentication keys 1 are compared.
If they match, the next phase 2 is started. If they do not match, the process ends abnormally.

Next, in the phase 2, the IC card 101
, A challenge key (Challenge Key) 2 is generated by the challenge key generation circuit 31c and transmitted to the decryption unit 104. Next, the IC card 10
1 generates an authentication key 2 (Key2) based on the challenge key 2 in each of the authentication key generation circuit 33c and the authentication key generation circuit 33a in the decryption unit 104. The generated authentication key 2 is transferred. Then, in the IC card 101, the comparison circuit 3
5c, the IC card 101 and the decryption unit 104
Are compared with each other for the two authentication keys 2 generated. If they match, the next phase 3 is started. If they do not match, the process ends abnormally.

In phase 3, the bus key generation circuit 37a of the decryption unit 104 and the bus key generation circuit 37c of the IC card 101 use the bus key (BUS Key) based on the authentication key 1 and the authentication key 2 respectively. ), That is, a temporary key Skr is generated.

Thus, the decoding unit 104 and I
The temporary key Skr is safely shared with the C card 101. In step S22, the unique secret key Kic is transmitted from the IC card 101 to the decryption unit 104 using the shared temporary key Skr.
That is, first, the encryption circuit 2 is
In step 10b, the secret key Kic unique to the IC card 101 is encrypted with Skr to obtain ESkr (Kic).
Next, C is sent from the IC card 101 to the decryption unit 104.
ESkr (Kic) is sent through the PU bus 103.
Then, in the decoding unit 104, the decoding circuit 207
b, encrypts ESkr (Kic) with Skr,
Get Kic.

In the step S23, the EKic (Skd) recorded on the recording medium 121 is sent to the decoding unit 104. Then, in the decryption unit 104, the decryption circuit 207c uses EKic (Sd
k) to obtain Sdk.

In step S 24, the ESdk (Data) recorded on the recording medium 121 is
Send to Then, the ESdk (Data) is decrypted by the decryption circuit 207d using Sdk as a decryption key, and the original input data is obtained.

If the IC card used for encrypting the data to be decrypted is different from the IC card 101, the corresponding Kic is not stored in the IC card 101. Cannot be decrypted. In other words, in the present embodiment, decryption can be performed only by using the recording medium 121 and the IC card used to record the encrypted data on the recording medium 121 as a set. If the IC card becomes damaged and cannot be used, the data encrypted and recorded using the IC card cannot be decrypted.
The same Ki by the organization that manages the key Kic unique to the card
If the IC card storing c is reissued, it can be decrypted again.

The procedure shown in the present embodiment is an example and can be variously modified. For example, in FIG. 4, the order of steps S11 to S15 can be changed as appropriate. If there is a buffer in the encryption unit, data may be read at any timing. Also, all data may be encrypted and then recorded on the recording medium, but encryption and recording (or reading, encryption and recording) may be repeated for each predetermined unit.

For example, in FIG. 8, if there is a buffer in the decoding unit, EKic (Skd) or E
Sdk (Data) may be read from the recording medium at any timing. Further, all the encrypted data may be output after being decrypted, or decryption and output (or reading, decryption and output) may be repeatedly performed for each predetermined unit.

The same encryption system may be used in the above-described encryption circuit and decryption circuit in all parts, or the encryption system used in each pair of the encryption circuit and the decryption circuit may be used separately. The method may be determined as appropriate (all may be different).

In the above description, the encryption circuit and the decryption circuit are shown as independent circuits. However, if the encryption system and the decryption circuit are the same, one or a plurality of circuits can be shared in the unit. It may be configured to perform
For example, in the encryption unit 102, the encryption circuit 11
If the encryption systems 7b to 117e are all the same, they may be configured by one circuit, or may be configured as two or three circuits by appropriately sharing them. For example, if the encryption methods of the encryption circuits 117b and 117d are the same and the encryption methods of the encryption circuits 117c and 117e are the same (the former and the latter are different), the encryption circuit 117
b and 117d may be composed of one circuit,
The encryption circuits 117c and 117e may be constituted by one circuit.

In the present embodiment, the encryption unit is built in the PC as, for example, an encryption board and connected to the CPU bus. However, the encryption unit may be built in the disk drive.

(Second Embodiment) FIG. 9 shows a second embodiment of the present invention.
It is a block diagram showing the composition of the system used for data encryption concerning an embodiment. FIG. 10 shows the details of the portion 213, 214, and 215 in FIG. 9 and the temporary key generation circuit 107. An example of the operation in this case is shown in the flowchart of FIG.

FIG. 12 is a block diagram showing a configuration of a system used for decoding data according to the second embodiment of the present invention. The details of the portion 213 and 215 in FIG. 12 and the temporary key generation circuit 107 are as shown in FIG. An example of the operation in this case is shown in the flowchart of FIG.

As shown in FIG. 9, the system according to the present embodiment includes an IC card 101, an encryption unit 102, and a decryption unit 104. In addition, IC card 1
01, the encryption unit 102, and the decryption unit 104
Are connected to the CPU bus 103 of the PC. In addition,
It is desirable to connect the IC card 100 only when it is used, and to remove and store the IC card 100 in other cases.

Further, a disk drive device (not shown) is connected to the CPU bus 103, and the disk drive device reads and writes data on the recording medium 121. As shown in FIG. 9, FIG. 10, and FIG.
01 is a decryption circuit 115 as a part used for encryption.
And the encryption circuit 210b
And encryption circuits 114a and 114b and a temporary key determination circuit 211 as parts used for both encryption and decryption. The above components are formed as one independent IC chip and are sealed in the IC card.

The IC card 101 has a portion used for encryption (FIG. 9) and a portion used for decryption (FIG. 1).
Alternatively, the two IC cards may be separated into two and configured as two IC cards.

The encryption unit 102 includes the encryption circuit 11
7a to 117f, and a temporary key determination circuit 210.
The encryption unit 102 is formed as one independent IC chip.

The decryption unit 104 includes a data encryption key generation circuit 105 and a decryption circuit 110b as parts used for encryption, and decryption circuits 207b to 207d as parts used for decryption. Temporary key generation circuit 107, decryption circuit 11
0a and 110c. Decryption unit 104
Are formed as one independent IC chip.

The decryption unit 104 is divided into two parts: a part used for encryption (FIG. 9) and a part used for decryption (FIG. 12).
Chip).

In the decryption unit 104, a plurality of master keys Mks (109a in the figure) described later are registered (created). Also, the encryption unit 102
A plurality of master keys Mks (109b in the figure) identical to the decryption unit 104 are registered (created).

Similarly, a plurality of master keys Mks (109c in the figure) identical to the decryption unit 104 are registered (created) in the IC card 101. If the master key is found to have been broken,
Thereafter, a master key is created in the decryption unit 104 except for the broken one. However, as for the IC card 101 and the encryption unit 102, a master key may or may not be created except for the torn one. In addition, it is desirable that the decryption unit 104 in which the broken master key is created be replaced with a new one in which the master key is created except for the broken master key. However, IC card 1
01 and the encryption unit 102 may use the one in which the broken master key is created as it is.

It is assumed that the overall control is performed by a control unit (not shown). The control unit can be realized, for example, by executing a program by the CPU of the PC. The data Data is input data to be encrypted and recorded, and is, for example, multimedia data such as video, audio, and text input from an I / O port of a PC.

Sdk is a data encryption key (common key in the common key cryptosystem) used for encrypting and decrypting data. In the present embodiment, the Sdk is generated (changed) for each set of data (for example, for each title). The Sdk may be generated (changed) for each disk, may be generated (changed) for each side of the disk or for each set of a plurality of disks, or may be generated for each group. The data may be generated (changed) for each subdivided portion (for example, for each chapter or for each song).

The Kic is recorded in a secret area of the IC card 101 which cannot be taken out by the user.
This is a secret key (common key in the common key cryptosystem) unique to the IC card 101. This secret key Kic is different for each IC card.

Mks (s = 1 to n, n is an integer of 2 or more)
Is a key ring of a master key (a common key in a common key cryptosystem). For example, a predetermined number of master keys are assigned to each maker. In this case, the master key is assigned so that there is no duplication between the manufacturers. Here, as an example, if s = 1,... 10 (s = 10), then Mk
, Mk2,..., Mk10 are stored in the IC card 101, the encryption unit 102, and the decryption unit 104.
It is made in each of.

As described above, the key bundle of the master key is used by each of the chip sealed in the IC card, the chip of the encryption unit, and the chip of the decryption unit so that the user cannot obtain it from outside. It is assumed that the information is recorded in a concealed area inside the chip so that the user cannot intentionally remove the chip.

Skt is a temporary key (common key in a common key cryptosystem) for decrypting information (decryption performed prior to encryption) when flowing information on the CPU bus 103, and is generated each time. You.

The data encryption key generation circuit 105 generates a data encryption key Sdk. Data encryption key generation circuit 105
May be constituted by a random number generator for the key length, for example. In generating a random number, time information from a clock (not shown) may be used. In addition,
When a key is generated with a random number in which all bits may be 0 or 1, it is necessary to perform a check process or the like so that all bits do not become 0 or 1.

The temporary key generation circuit 107 is for generating a temporary key Skt, and generates it each time. The temporary key generation circuit 107 may be configured with a random number generator for the key length, for example. In generating a random number, time information from a clock (not shown) may be used. When a key is generated using a random number in which all bits may be 0 or 1, it is necessary to perform a check process or the like so that all bits do not become 0 or 1.

Note that the data encryption key generation circuit 105 and the temporary key generation circuit 107 provide the data encryption key Sdk and the temporary key Sk
It is also possible to configure as one key generation circuit capable of generating both of t.

The recording medium 121 is for recording input data from an encrypted I / O port. For example, a hard disk, an MO, an FD, a once-writable CD, a DVD-RAM, or the like is used. Can be considered.

In some cases, the disk drive device includes a modulation / demodulation / error correction circuit that performs a modulation and error correction circuit during recording and performs a demodulation and error correction circuit during reproduction.

In this embodiment, the decoding unit 1
04 is provided with a D / A conversion circuit for converting digital data Data into analog data.
It is assumed that data converted from analog is output from 04. When the digital data Data is to be decoded, a decoding circuit for decoding the digital data is D / A.
It shall be provided before the conversion circuit. For example, when the digital data Data is image data compressed by the MPEG system, an MPEG decoding circuit is provided. Also, a plurality of types of decoding circuits are provided so as to be able to output either data compressed or the like by various methods or data that does not need to be decoded, and these are switched appropriately and used, or these are not used. It is also possible. The output from the decoding unit 104 is displayed on a display as an image, for example.

First, the procedure at the time of encryption will be described with reference to FIGS. First, IC card 1
01 is inserted into a card slot or the like (not shown) of the PC. If the recording medium 121 is a removable medium, it is set in a disk drive (not shown).

In step S31, the decoding unit 10
At 4, the temporary key generation circuit 107 generates the temporary key Skt and the data encryption key generation circuit 105 generates the encryption key Sdk for encrypting the input data.

In step S32, the generated temporary key Skt is transmitted from the decryption unit 104 to the encryption unit 102 and the IC card 101 using the following procedure.
Tell

[0111] In order not to obtain the plain data of Skt, Skt is obtained by using any of the master keys Mks (s = 1, ..., n) recorded in the decryption unit 104 (this is Mki). The decrypted DMki (Sk
t) the encryption unit 1 through the CPU bus 103
02 and the IC card 101 respectively.

Here, if there is only one master key (this is Mk0), the Skt is simply decrypted by Mk0 in the decryption unit 104, and this DMk0 is decrypted.
(Skt) with the encryption unit 102 and the IC card 101
To the encryption unit 102 and the IC card 1
01, Skt can be extracted by encrypting DMk0 (Skt) with Mk0.
In the present embodiment, the identification information that directly points to the used master key Mki in the key bundle composed of a plurality of master keys is not transmitted from the decryption unit 104 to the encryption unit 102 and the IC card 101. To
The information enabling identification of the master key Mki is transmitted from the decryption unit 104 to the encryption unit 102 and the IC card 1.
01, each of the encryption unit 102 and the IC card 101 specifies which of the n master keys the master key Mki used for encrypting the Skt is. Skt is obtained through the specification of

Hereinafter, a more detailed procedure of step S32 will be described. First, in the encryption unit 102, the n master keys Mks (i
= 1,..., N), the temporary key Skt is decrypted with one selected randomly or sequentially (this is Mki) to obtain DMki (Skt). The decryption circuit 110c decrypts the Skt using the temporary key Skt itself as an encryption key to obtain DSkt (Skt).
Then, DMki (Skt) and DSkt (Skt) are
Encrypting unit 102 and IC through CPU bus 106
Each is sent to the card 101.

Next, the same processing is performed in each of the encryption unit 102 and the IC card 101. First, the processing in the encryption unit 102 will be described. The encryption unit 102 first selects one master key (this is referred to as Mkp).

Using the selected Mkp as an encryption key, DMki (Skt) is encrypted by the encryption circuit 117a to obtain EMkp (DMki (Skt)) = Ska.

Next, DSkt is output by the encryption circuit 117f using the output Ska of the encryption circuit 117a as an encryption key.
(Skt) is encrypted to obtain ESka (DSkt (Skt)) = Skb.

Next, the temporary key determination circuit 210
It is checked whether a and Skb match. Here, the master key Mki obtained by decrypting the Skt in the decryption unit 104
Is Mkp, then Ska = EMkp (DMki (Skt)) = Skt, and therefore Skb = ESka (DSkt (Skt)) = ESkt
(DSkt (Skt)) = Skt, and therefore Ska = Skb = Skt.

That is, the temporary key determination circuit 210
If it is found that ka and Skb match, M
ki = Mkp and Ska = Skb = Skt,
In this case, the temporary key determination circuit 210 determines that Ska = Skb = S
kt is output.

On the other hand, the temporary key determination circuit 210
If a and Skb do not match, then M
ki ≠ Mkp, and Skt
Is not decrypted with this Mkp, but decrypted with another master key. In this case, the temporary key determination circuit 210 does not output (or the temporary key determination circuit 21
0 is not transmitted to the encryption circuits 117b and 117d).

Thereafter, the above procedure is repeated until the master key Mkp used for decryption is changed until Ska and Skb match. For example, if the above procedure is first performed using Mk1 as Mkp and Ska and Skb do not match, then the procedure is updated to Mk2 and the above procedure is repeated again.

Using the above procedure, the encryption unit 102 can specify which master key was used in the decryption unit 104, and the communication between the encryption unit 102 and the decryption unit 104 can be performed. It is possible to safely share the temporary key Skt between them.

Next, the processing in the IC card 101 will be described. First, one master key is selected on the IC card 101 (this is referred to as Mkp). Using the selected Mkp as an encryption key, DMki (Sk
Encrypt t) to get EMkp (DMki (Skt)) = Ska.

Next, using the output Ska of the encryption circuit 114a as an encryption key, the
(Skt) is encrypted to obtain ESka (DSkt (Skt)) = Skb.

Next, the temporary key determination circuit 211
It is checked whether a and Skb match. Here, the master key Mki obtained by decrypting the Skt in the decryption unit 104
Is Mkp, then Ska = EMkp (DMki (Skt)) = Skt, and therefore Skb = ESka (DSkt (Skt)) = ESkt
(DSkt (Skt)) = Skt, and therefore Ska = Skb = Skt.

That is, the temporary key determination circuit 211
If it is found that ka and Skb match, M
ki = Mkp and Ska = Skb = Skt,
In this case, the temporary key determination circuit 211 determines that Ska = Skb = S
kt is output.

On the other hand, the temporary key determination circuit 211
If a and Skb do not match, then M
ki ≠ Mkp, and Skt
Is not decrypted with this Mkp, but decrypted with another master key. In this case, the temporary key determination circuit 211 does not output (or the temporary key determination circuit 21
1 is not transmitted to the decoding circuit 115).

Thereafter, the above procedure is repeated by changing the master key Mkp used for decryption until Ska and Skb match. For example, if the above procedure is first performed using Mk1 as Mkp and Ska and Skb do not match, then the procedure is updated to Mk2 and the above procedure is repeated again.

Using the above procedure, the IC card 101 can specify which master key is used in the decryption unit 104, and the communication between the decryption unit 104 and the IC card 101 can be performed. The temporary key Skt can be safely shared.

In step S33, first, the IC card 1
At 01, the decryption circuit 115 decrypts the secret key Kic unique to the IC card 101 using the temporary key Skt to obtain DSkt (Kic). And DSkt
(Kic) is sent to the encryption unit 102 through the CPU bus 103. Next, in the encryption unit 102, the encryption circuit 117d uses the temporary key Skt to generate DSkt (Ki
Encrypt c) to get Kic.

In step S34, first, in the decryption unit 104, the temporary key S
Decode Sdk with kt to obtain DSkt (Sdk).
Then, DSkt (Sdk) is sent to the encryption unit 102 through the CPU bus 103. Next, in the encryption unit 102, the temporary key Skt is generated by the encryption circuit 117b.
Encrypts DSkt (Sdk) to obtain Sdk.

At step S35, the encryption unit 10
At 2, the Sdk is encrypted by the encryption circuit 117e using Kic as an encryption key to obtain EKic (Sdk). Then, EKic (Sdk) is recorded on the recording medium 121.

At step S36, the encryption unit 10
In step 2, the input data Data is encrypted by the encryption circuit 117c using Sdk as an encryption key,
(Data) is obtained. Then, the ESdk (Data) is recorded on the recording medium 121.

It should be noted that a plurality of EKic can be stored in one recording medium.
When (Sdk) is stored, EKic (Sdk) and E
Sdk (Data) are stored in association with each other. Next, a procedure at the time of decoding will be described with reference to FIG. 12, FIG. 10, and FIG.

First, the IC card 101 is inserted into a card slot or the like (not shown) of the PC. If the recording medium 127 is a removable medium, it is set in a disk drive (not shown).

In step S 41, a temporary key Skt used to send a secret key Kic unique to the IC card 101 to the decryption unit 104 via the CPU bus 103 is transmitted to the decryption unit 104 by the temporary key generation circuit 107. Generate.

In the step S42, the previous step S34
Using the same procedure as that used in the above, the decryption unit 104 sends the generated temporary key S to the IC card 101.
kt.

In the step S43, first, the IC card 1
At 01, the encryption circuit 210b encrypts Kic with the temporary key Skt to obtain ESkt (Kic). Then, ESkt (Kic) is sent to the decoding unit 104 through the CPU bus 103. Next, the decryption unit 10
At 4, the decryption circuit 207 b outputs E to the temporary key Skt.
Skt (Kic) is decoded to obtain Kic.

In step S44, EKic (Skd) recorded on the recording medium 121 is sent to the decoding unit 104. Then, in the decryption unit 104, the decryption circuit 207c uses EKic (Sd
k) to obtain Sdk.

At step S45, the ESdk (Data) recorded on the recording medium 121 is decoded by the decoding unit 104.
Send to Then, the ESdk (Data) is decrypted by the decryption circuit 207d using Sdk as a decryption key, and the original input data is obtained.

The procedure shown in the present embodiment is an example and can be variously modified. For example, in FIG.
The order of steps S31 to S35 can be changed as appropriate. If there is a buffer in the encryption unit, data may be read at any timing. In addition, all data may be encrypted and then recorded on the recording medium, or encryption and recording (or reading, encryption and recording) may be repeated for each predetermined unit.

In FIG. 13, for example, if there is a buffer in the decoding unit, EKic (Skd) or ESdk (Data) may be read from the recording medium at any timing. Further, all the encrypted data may be output after being decrypted, or decryption and output (or reading, decryption and output) may be repeatedly performed for each predetermined unit.

As in the first embodiment, the same encryption scheme may be used in the above-described encryption circuit and decryption circuit in all parts, or the same encryption scheme may be used in the encryption circuit and the decryption circuit. The encryption method to be used may be determined as appropriate for each set of circuits (all may be different).

As in the case of the first embodiment, one or a plurality of encryption circuits and decryption circuits may be used in a unit or an IC card if the encryption system is the same. It does not matter. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the technical scope.

[0144]

According to the present invention, together with the data encrypted with the data encryption key, the data encryption key is encrypted with the unique secret key stored in the external storage device and recorded on the recording medium. By not storing the data encryption key,
Unless an external storage device that stores the unique secret key used for encryption is used, decryption cannot be performed.

Further, according to the present invention, the data encryption key and the unique secret key are encrypted using a temporary key, and the like.
Since the information is shared between the devices via the U bus, even if the information flowing on the CPU bus is recorded, it cannot be used later.

Further, according to the present invention, the data encryption key itself for encrypting data and the temporary key used for sharing the data encryption key change each time, so that the third party can decrypt the data. It is extremely difficult to do.

Therefore, according to the present invention, unauthorized copying by a third party can be prevented. As a result, creation of a pirated copy or the like can be prevented beforehand, and copyright can be protected effectively.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a system used for encryption according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of an internal configuration of the key sharing circuit of FIG. 1;

FIG. 3 is a diagram showing an example of an internal configuration of the key sharing circuit of FIG. 1;

FIG. 4 is a flowchart showing a procedure at the time of encryption in the embodiment;

FIG. 5 is a flowchart illustrating an example of a key sharing procedure.

FIG. 6 is a block diagram showing a configuration of a system used for decoding according to the embodiment;

FIG. 7 is a diagram showing an example of the internal configuration of the key sharing circuit in FIG. 6;

FIG. 8 is a flowchart showing a procedure at the time of decoding in the embodiment.

FIG. 9 is a block diagram illustrating a configuration of a system used for encryption according to a second embodiment of the present invention.

FIG. 10 is a diagram showing an example of a detailed configuration of components 213 to 125 for key sharing.

FIG. 11 is a flowchart showing a procedure at the time of encryption in the embodiment;

FIG. 12 is a block diagram showing a configuration of a system used for decoding according to the embodiment;

FIG. 13 is a flowchart showing a procedure at the time of decoding in the embodiment.

[Explanation of symbols]

30a, 30b, 30c key sharing circuit 31a, 31b, 31c challenge key generation circuit 33a, 33b, 33c authentication key generation circuit 35a, 35b, 35c comparison circuit 37a, 37b, 37c bus key generation circuit 101 IC Card 102 Encryption unit 103 CPU bus 104 Decryption unit 105 Data encryption key generation circuit 107 Temporary key generation circuit 109a to 109c Master key bundle 114a, 114b, 117a to 117f, 210b
Encryption circuits 115, 110a to 110c, 207b to 207d Decryption circuit 121 Recording media 210, 211 ... Temporary key determination circuit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akio Tanaka 2-9-9 Suehirocho, Ome-shi, Tokyo Inside the Toshiba Ome Plant (72) Inventor Nobuhiro Yoshida 2-9-9 Suehirocho, Ome-shi, Tokyo Stock Company Toshiba Ome Factory

Claims (12)

[Claims] 1. A method according to claim 1, wherein data input without passing through a CPU bus of a computer is encrypted with a predetermined data encryption key before being recorded on a predetermined recording medium, and said predetermined data encryption key is also stored on said recording medium. An external storage device having a processing function connected to the CPU bus of the computer for use in a device for encrypting with a predetermined secret key before recording. Means for recording in a confidential form; and for securely transmitting the unique secret key to the encrypting device via the CPU bus of the computer as the predetermined secret key without being obtained from outside. And an external storage device. 2. A computer which is read from a predetermined recording medium and is
A data encryption key encrypted with a predetermined secret key given via the PU bus is decrypted, read out from the recording medium using the obtained data encryption key, and given via the CPU bus. An external storage device having a processing function connected to the CPU bus of the computer and used for a device for decrypting data encrypted with a predetermined data encryption key, and a secret unique to the device itself. Means for recording the key in a form concealed from the outside, and secure the secret key unique to the decryption device via the CPU bus of the computer as the predetermined secret key without being obtained from outside. An external storage device comprising: 3. An encryption unit device for encrypting data input without passing through a CPU bus of a computer before recording the data on a predetermined recording medium, wherein the data is encrypted from a predetermined external storage device via the CPU bus. Means for securely receiving a private key unique to the external storage device recorded in the external storage device in a form concealed from the outside without being obtained from the outside; and a data encryption key. Means for securely receiving the generated data encryption key from the generating device via the CPU bus without being obtained from outside, and the data encryption received using the received unique secret key An encryption unit comprising: means for encrypting a key; and means for encrypting the data to be encrypted using the received data encryption key. . 4. A decryption unit device connected to a CPU bus of a computer and used for decrypting encrypted data recorded on a predetermined recording medium, wherein the decryption unit device transmits the data from a predetermined external storage device to the CPU bus. Means for securely receiving a private key unique to the external storage device recorded in the external storage device in a form concealed from the outside without being obtained from the outside; and To obtain a data encryption key by decrypting a data encryption key read from the recording medium and encrypted with the unique secret key given via the CPU bus, using a unique secret key as a decryption key. Means for decrypting data read from the recording medium and encrypted with the data encryption key given via the CPU bus, using the obtained data encryption key as a decryption key. Decoding unit device characterized by comprising and. 5. A decryption unit connected to a CPU bus of a computer for decrypting encrypted data recorded on a predetermined recording medium, wherein the decryption unit device does not pass through the CPU bus of the computer. An encryption unit device for encrypting input data generates a data encryption key used for encrypting data to be encrypted, and
Means for securely transmitting the data encryption key to the encryption unit device via a bus without being acquired from the outside; and from a predetermined external storage device to the external storage device via the CPU bus. Means for securely receiving a secret key unique to the external storage device recorded in a form concealed from the outside without being obtained from outside, and using the received unique secret key as a decryption key, Means for decrypting a data encryption key read from a recording medium and encrypted with a unique secret key given via the CPU bus to obtain a data encryption key; and the obtained data encryption key. Means for decrypting data read from the recording medium and encrypted with the data encryption key given via the CPU bus, using the encryption key as a decryption key. Unit apparatus. 6. A predetermined conversion process is performed on original data obtained by decrypting encrypted data read from the recording medium, and then output to the outside without passing through a CPU bus of the computer. 6. The decoding unit according to claim 4, further comprising: 7. An external storage device having a processing function connected to a CPU bus of a computer, a device for generating a data encryption key, and an encryption unit device, which are externally input without passing through the CPU bus. An encryption system for encrypting data before recording the data on a predetermined recording medium, wherein the external storage device is configured to record a secret key unique to the device in a form concealed from the outside, Means for securely transmitting the unique secret key to the encryption unit device via a CPU bus without being obtained from the outside, wherein the device for generating the data encryption key comprises: Means for generating a data encryption key used for encrypting data to be encrypted, and obtaining the data encryption key from the outside to the encryption unit device via the CPU bus Means for securely transmitting the unique secret key from the external storage device via the CPU bus without being obtained from outside. Means for securely receiving the data encryption key from the device for generating the data encryption key via the CPU bus without being externally obtained; and receiving the data encryption key using the received unique secret key. Encryption means for encrypting the data encryption key, and means for encrypting the data to be encrypted using the received data encryption key. system. 8. The means for transmitting and the means for receiving are each provided with a predetermined temporary key from the outside by a predetermined key sharing procedure which is performed cooperatively by exchanging information via a CPU bus of the computer. Means for sharing without being obtained, means for communicating, means for decrypting the generated data encryption key with the shared temporary key and outputting, and means for receiving 8. The encryption system according to claim 7, further comprising means for encrypting the data encryption key decrypted with the given temporary key with the shared temporary key. 9. A decryption system for decrypting encrypted data recorded on a predetermined recording medium using an external storage device having a processing function connected to a CPU bus of a computer and a decryption unit device. The external storage device includes: means for recording a secret key unique to the device in a form concealed from the outside; and acquiring the unique secret key to the decryption unit device from the outside via the CPU bus. Means for securely transmitting the unique secret key from the external storage device via the CPU bus without being obtained from the outside. Means for encrypting data read from the recording medium and encrypted with the unique secret key given via the CPU bus, using the received unique secret key as a decryption key Means for decoding a data encryption key, and using the obtained data encryption key as a decryption key, a data encryption key read from the recording medium and given via the CPU bus. Means for decrypting the encrypted data. 10. The means for transmitting and the means for receiving are each provided with a predetermined temporary key from the outside by a predetermined key sharing procedure which is performed cooperatively by exchanging information via a CPU bus of the computer. Means for sharing without being acquired, means for communicating, means for encrypting the generated data encryption key with the shared temporary key and output, and means for receiving 10. The decryption system according to claim 9, further comprising means for decrypting the data encryption key decrypted with the given temporary key using the shared temporary key. 11. An external storage device having a processing function connected to a CPU bus of a computer, a device for generating a data encryption key, and an encryption unit device, which are externally input without passing through the CPU bus. An encryption method for encrypting data before recording it on a predetermined recording medium, wherein the encryption is performed from the external storage device to the encryption unit device via the CPU bus and is concealed from the outside in the external storage device. Secret key unique to the external storage device recorded in the form of
While securely transmitting without being obtained from the outside, the data encryption key generated by the data encryption key is transmitted from the device for generating the data encryption key to the encryption unit device via the CPU bus. In the encryption unit device, the received data encryption key is encrypted using the received unique secret key, and the received data encryption key is used. And encrypting the data to be encrypted. 12. A decryption method for decrypting encrypted data recorded on a predetermined recording medium using an external storage device having a processing function connected to a CPU bus of a computer and a decryption unit device. From the external storage device to the decryption unit device via the CPU bus, a secret key unique to the external storage device recorded in the external storage device in a form concealed from the outside,
While securely transmitting without being acquired from the outside, the decryption unit device reads the unique secret key received from the recording medium as a decryption key and provides the unique secret key given via the CPU bus. The data encryption key decrypted with the secret key is decrypted to obtain a data encryption key, and the obtained data encryption key is read out from the recording medium and given through the CPU bus as a decryption key. A decryption method for decrypting data encrypted with the encrypted data encryption key.