Method and system for the secure transmission and storage of protectable information

Abstract: The present invention describes a method and system for the secure transmission and storage of protectable information, in particular, of patient information, by means of a patient card. The data stored on the patient card are protected by cryptographic methods. The data can be decrypted only with the same patient card if a doctor is authorised and the patient has given his agreement. All information which the patient card needs in order to decide whether the doctor is authorised and the key for protecting the control data and the random key are held on the chip. The patient data can be freely transmitted to any storage medium. The chip controls both the access to the data and the encryption and decryption functions. Random keys, which are themselves stored encrypted together with the data ensure that every data record remains separate from every other and that only authorised persons can access it. Every patient card has its own record key. The system and method in accordance with the invention is not directed exclusively to patient data but can be applied to any protectable data to which right of access is to be restricted.

Description: The invention relates to a method and a system for the secure transmission and storage of protectable information, in particular, of patient information stored on a patient card system. Patient card systems should primarily serve the interests of the patient. The person-related medical data of a person stored on the patient card is particularly sensitive and hence worth protecting. In addition patients are often in a very weak state and are not in a position to deal positively with their protection. Consequently, laws and agreements must be adopted in order to set in place the legal and technical framework which will support the patient in protecting these sensitive cards. Chip cards offer all the necessary control mechanisms with which the data in the non-volatile storage on the chip are protected. On one hand, the chip is effectively protected against physical access from outside, on the other hand an operating system monitors all accesses to the data and rejects attempts to read and/or write if the user cannot be authenticated and/or cannot enter a PIN. The chip thus prevents the protected data being read from outside through its data lines. Because of their recognised high security, chip cards are employed as identification systems primarily in the financial area. The optical storage of the optical memory chip card uses the known technology employed in CDs and CD-ROMs. Because of its high storage capacity it is well suited to the storage of large amounts of data. It is, however, a disadvantage of this storage, that it provides no physical protection for the data; anyone who has a reader can read the data. In spite of this, the data can be protected logically in that the data can be stored in encoded form. The coding of the data is also known under the technical term "cryptography". The problem with all symmetrical encryption procedures is the confidential distribution of the decryption key between the parties involved. The greater the number of parties who wish to communicate with one another, the more insurmountable the problem of key management becomes. It would be easy to solve if all participants were to use the same key; however, this would mean that every one of them could read what two participants had encrypted between them and, in the event of a successful access from outside to this one key, the whole system would be open. If each participant were to have his own key, successful access to a key would be limited to the information which is sent to and received by one key holder. The other keyholders remain protected. The problem of key exchange is even more problematical when it involves not just one sender and several receivers, that is, a 1-to-N relationship, but an n-to-N relationship. For example, every doctor may be the sender of information and any other authorised doctor must be able to read it. As already stated, the doctors should in no case have to agree a key which can be used throughout the whole system before they can get into communication. On the other hand, the participating doctors cannot all be expected to exchange their keys with one another beforehand. European Patent EP 0668 578 describes a memory and selective information system for the transfer of sensitive data comprising an optical memory card, on which a spatially defined storage field for the exclusive storage of a plurality of codes arranged at least one to each key access, at least one read/write device for the optical memory card with a plurality of key-recognition functions, where each key recognition function points to each of a plurality of formatting functions contained in the read/write device and activates the latter in conjunction with the code assigned to each, where each formatting function points to a data storage field of the optical card and qualifies the data stored thereon for reading on the basis of the formatting data. One disadvantage of this process is that there is a key region and a data region on the optical storage medium. Two separate accesses to the optical storage medium are therefore necessary in order to read the key and the data. The process described in EP 0668 578 uses fixed keys, i.e. keys are predetermined in accordance with a particular procedure by the system. The read/write device is an important constituent for the decision as to which key should be used. This depends on the code, the formatting functions and the decision functions. Usually the present process is limited only to optical storage media. US Patent 4,238,854 discloses a file security system for data files associated with a host data processing system. The host system includes a data security device which contains a secure host master key and is capable of performing a variety of cryptographic operations. At initialization time, the host system generates a series of file keys for the associated storage media and protects them by enciphering the file keys under a variant of the host master key. When a data file is to be created, a random number is generated and defined as an operational key enciphered under the file key of a designated storage media. The host data security device, using the enciphered file key of the designated storage media, transforms the enciphered operational key under control of the host master key into a form which permits the operational key to be used for enciphering host data. The operational key enciphered under the file key of the designated storage media, as header information, together with the host data enciphered under the operational key is written on the storage media as an enciphered data file. When the data file is recovered, the host data security device, using the enciphered file key of the designated storage media, transforms the enciphered operational key header information under control of the host master key into a form which permits the operational key to the used for deciphering the enciphered data file to obtain the file data in clear form. It is therefore an object of the present invention to propose a system and method for the transfer of information which requires to be protected which allows a maximal exchange of the said information between a plurality of users but ensures in doing so that the system/method only permits the entry and reading of said information to those authorised therefor. This object is achieved by the features of the independent claims. Advantageous embodiments of the present invention are set out in the sub-claims. In the present invention the encrypted data and the associated key are stored together in one file. In this way the encrypted data can be stored without security risk anywhere, e.g. in a computer, in a database or can be distributed over a network, regardless of the storage medium on which they were initially recorded. Within the file there may be data of differing degrees of confidentiality which can only be written or read with certain access authorizations. The data are stored encrypted with a random key. The random key, for its part, is encoded in the chip card and stored with the data. In this way, the decryption of the data is made considerably more difficult. The method of key generation takes place exclusively on the chip card. The authorised person consequently always has full control over access to his data. The preferred embodiment of the present invention is hereinafter explained and described in more detail with the aid of drawings, where FIG. 1 is a diagrammatic representation of the file structure in accordance with the invention and FIG. 2 is a flow chart of the reading and writing process illustrating the information and transfer system in accordance with the invention. FIG. 3 shows the method of operation of the information and transfer system in accordance with the invention with the aid of the requisite hardware. FIG. 1 shows the structure of the file structure in accordance with the invention consisting of the header and the data record. The header consists, for example, of the control data fields 1-7. The data record may consist of several data types 1-n, which are stored in the data record. Each type of data is coded with its own random key. This random key and a part of the control data which has to be protected, is in turn encrypted with a fixed key stored on the chip card. The chip card itself encrypts the control data and the random key; in this way the confidential fixed key never leaves the chip card. The secrecy stage, for example, of the data types contained in the files, is laid down in management fields 1 and 7, that is, each data type is characterised by its own secrecy stage with the associated key. There are data types which should always be readable, such as, for example, emergency data. Then there are data types which must only be readable with the agreement of the patient and/or only be accessible to certain groups of user. Which data are to be classified in which data type will depend on the data protection legislation of the country concerned. As a general rule, each data type should be accessible only to certain user groups. For example, chemists should only be able to access data which they require for their activities. The authorised user groups which have access to a particular data type are defined in the management fields. For example, it can be decided that the chemists can only have access to recipes and doctor's advice on contraindications. The following data types can therefore be established: Type 0 data - data are always readable - data are not encrypted. Type 1 data - data are only readable after entry of the patient's PIN. Type 2 data - data can only be read after authorization by a doctor in any speciality and after entry of the patient's PIN. Type 3 data - as for Type 2 data; with the addition that here the data can only be read after authorization by a doctor in a specific speciality. Type 4 data - reserved for later use. Type 5 data - the data can, for example, be read by both doctor and chemist without requiring the patient's PIN. This type of data can be directed towards members of a particular group, e.g. only to radiologists, chemists or to all. Several precisely specified target groups can also be entered as a list. The types of data mentioned are stored in the data record separate from one another. In addition, data of various specialist groups or data intended only for a specific target group are each held in different files. Each data record includes control data from which the type of data record (emergency data/chemist's data/clinical data), the types 0...5 of data contained, the speciality of the doctor who wrote the data record, his name, his identification, data, time and the target group for the data, can be determined. The target groups who may read the data can also be defined as "all". Each type of data is encrypted with its own random key. This random key and a part of the control data which has to be protected is, for its part, encrypted with a fixed key stored on the chip card. The chip card itself encrypts the control data and the random key; consequently, the secret fixed key never leaves the chip card. Only the chip itself encrypts the control data and random key, after it has checked whether either the doctor could be authorised for either the target group held in the control information. If the doctor does not belong to this target group, then he may only access these data with the agreement of the patient. Fig. 2 describes the individual steps in the reading and writing of the data in the form of a flow diagram. Prerequisites for the reading and writing of data by means of the system and method in accordance with the invention are the patient card, user card, reading and writing device and a computer system for controlling the process. Particularly suitable as patient cards are optical cards. Any other chip card may also be employed. The patient card consists preferably of an optical bulk storage and a chip, which contains the cryptographic function. The chip of an optical chip card further serves as the protected communication channel over which two parties can transmit a key while it stores the key securely. Each patient card contains its own record key, which does not even need to be known to the card supplier. The patient card never discloses the key to the exterior. The patient card blocks the encryption and decryption functions until a doctor duly authorises it. In reading a file the doctor must be in possession of a user card. The user card legitimises the doctor as an authorised doctor in a particular specialty. The user card is read by a reader or reading/writing device. The user card is technically not absolutely essential for every legitimation since the user group information on the doctor may already be set down in secure form in the doctor system. In addition, it is necessary for the patient to insert his patient card into a reading/writing device. If the doctor is authorised, the system first gives him access to data which is accessible to every user group. These data are also not encrypted (emergency data). If the doctor requires access to protected data, the user card must contain information on the group to which the doctor belongs (e.g. dermatologist, pulmonary doctor, etc.). For this the system takes the relevant information on the user group to which the user belongs from the user card and calls up an authorization command from the patient card. The patient card verifies whether the user belongs to the user group mentioned and holds this information on the patient card. A user may belong to several user groups. The system then reads a file which contains medical data on the patient and separates the file into data header and data record. The data header with the control data with a decryption command is then transmitted to the patient card. Before the patient card decrypts the data header, it checks to see whether there is any authorization. In the event that there is an authorization and that the user is identical with the user group of the target group of the data header, it returns the decrypted data header to the system. The system takes the desired key from the data header and sends it to the patient card for decryption. The decrypted key is returned to the system, whereupon the system now decrypts the data record of the corresponding data type with a suitable decryption program. In writing data the procedure is exactly the reverse, with the distinction that the key is produced by the data key generator on the patient card. In this way the system first encodes the data record, where each data type in the data record is encrypted with its own random key. The key is then sent to the patient card for encrypting. The data header is then built up and the system likewise sends the data header to the patient card for encrypting. The result is an encrypted data record with an encrypted key and encrypted control data, which are also required for access to the data. For example, it can be laid down that only doctors have the right to post medical data to the patient card or that chemists have only limited right to write and that they can only read and write data related to their specialty. Thus they can cancel a prescription if they have sold a medicine, can store notes on the manufacturer and batch number and the like. The patient must always first agree before the doctor can write medical data to the card. The doctor therefore has the responsibility of checking with the patient what he can write on the card, so that the patient can give his approval or disapproval. If a doctor wishes to write data to a patient card he must have been authorised as a doctor. This is effected as in the reading process by means of a user card. From the user card, the relevant specialist group is obtained. The patient must likewise be legitimised by entering his PIN as the authorised owner of the patient card and have given his agreement before the doctor can write to a file. Given the appropriate authorization key the patient card will establish that it relates to a doctor in a particular specialist group. A doctor may also be in possession of several authorization keys if he is a specialist in several fields. This encrypted data record with encrypted key and encrypted control data can be written to optical storage media or the chip of the optical storage card, stored in a computer or sent over a network. A doctor can again have access to this data only with the consent of the patient. It is also possible to file the data from an optical chip card and make a duplicate if the original is lost. Fig. 3 shows the basic structure of an information and transmission system for the storage and transmission of protected data, in particular patient data. The system consists in essence of a computer, a write/read device for patient cards, a patient card, a write/read device for the user card and a user card. Technically, it is also possible to employ a single write/read device for both the patient card and the user card. The patient data are either stored on the patient card or can be stored on any other desired storage medium. In cases where the patient data is stored on the patient card an optical mass memory is preferably used. The patient card is preferably a chip card with an optical mass memory. It is always necessary for writing or reading the data. The following important data/functions are stored on the patient card: Authorising key for the relevant user groups, encryption key for the data key, encryption key for the data header, generator for the production of data keys and encryption and decryption functions. The present invention was described using patient cards exclusively as an example. It should be stated, however, that the system and method in accordance with the invention can also be applied to all data worth protecting, where a limited right of access to certain data on a person, company, bank, an authority or other institution is to be permitted. This applies particularly to application with the following framework conditions: the owner of data can set up and use various security levels, the data may be made accessible only to a particular target group or a number of target groups, with certain security levels authorization of the right to read can be enforced (e.g. with the user card), with certain security levels an identification and agreement of the possessor of the chip card can be enforced e.g. by entry of a PIN. As an example of the use of the present invention a chip bank card may be considered, on which value of personal or company assets are stored. The owner of this chip bank card may only permit the relevant bank to have limited right of access. A further example could be a chip credit card. The present invention can therefore be applied to all applications for the storage and transmission of protectable data without any alteration to the method and system in accordance with the invention. The present invention can be briefly summarised as follows. The data stored on the patient card be protected by cryptographic methods. Only the same patient card can decrypt the data again, if the patient has agreed and a doctor is authorised. All information which the patient card uses in order to decide whether the doctor is authorised is stored, together with the key for the protection of the control data and random key, on the chip. The patient data can, but does not have to be stored on the chip. The chip controls both access to the data and also the encryption and decryption functions. Random keys, which are themselves stored encrypted together with the data, ensure that each data record remains separate and that only authorised persons have access. Each patient card has its own record key. Should the random key for one data record be broken, the other data records on the card and all other cards in the system remain unaffected. If the key to the encryption of the random keys of a patient card be broken, the data on all the other cards in the system would remain secure. The keys on the patient card used for authorization are derived from a feature of the patient card and therefore differ from patient card to patient card. If a patient card were broken, only the keys not yet used in the system would be open. Members of the health service authorise themselves in respect of the patient cards with their user cards. The user card contains a set of group keys which the system operator defines. Only if a doctor is authorised with a key and the patient has agreed with his PIN number, can the doctor access the data. The group key varies according to his job in the health service and in accordance with medical specialty. Data may be classified differently according to the need for protection. The classes differ according to whether a user requires to be authorised or not and whether the patient has to agree or not.

Claims: A storage and reading system comprising: a computer having a data link to a data storage medium which stores data belonging to a data owner, wherein said data are stored in files, each file comprises a data header and different data types, each data type represents data with the same secrecy stage and the same access condition, wherein said data type accessible only to certain user groups is encrypted with its own data type own random key which is encrypted by a chip card fixed key and stored in said data header, having a data link to a read/write device allowing data exchange between said computer and a chip card, wherein said chip card is to be assigned to a data owner, wherein said chip card includes said chip card fixed key for encryption of newly generated data type own random keys, and a generator for generation of new data type own random keys; having a data link to an authorization means for controlling access to said owners data on said storage medium according to its assigned access conditions, and having a data link to an identification means for giving data owner's confirmation to access owner's data on said storage medium. A system according to claim 1, wherein said data storage medium is part of said chip card. A system according to claim 1, wherein said data storage medium is part of said computer. A system according to claim 3, wherein said computer is arranged in a network and said storage medium is arranged in any computer of said network. A system according to claim 1, wherein said authorization means comprising an authorization terminal. A system according to claim 1, wherein said identification means comprising an identification terminal. Method for storing information by means of a data storage and reading system according to claim 1-6, comprising the steps of: authorizing a user for writing data by means of an identification feature assigned to said user via said data storage and reading system generating for type of data an own random key in said chip card, transmitting said own random key from said chip card to said computer, encrypting in said computer, a data record, where each data type in the data record is encrypted with its own random key, encrypting said random key in said chip card with said chip card fixed key, and storing said encrypted random key with said encrypted data record. Method according to claim 7, wherein storing said encrpyted random key with said encrypted data record only if confirmation of the data owner via said identification means is given. Method for reading information by means of a data storage and reading system according to claim 1-6, comprising the steps of: authorizing a user for reading a file by means of an identification feature assigned to said user via said data storage and reading system: transmitting said file from the storage medium to said computer, wherein said file comprises an encrypted data header and encrypted data, transferring said encrypted data header from said computer to said chip card, decrypting said encrypted data header into decrypted data header by means of a chip card fixed key stored in said chip card, the decrypted header having an own random key, transmitting said decrypted header from said chip card to said computer, decrypting the encrypted data by means of said own random key. Method according to claim 9, wherein decrypting the encrypted data only if confirmation of the data owner via said identification means is given.

Inventors: DEINDL MICHAEL, WITZEL MARTIN, DEINDL, MICHAEL, WITZEL, MARTIN
Applicants: IBM, INTERNATIONAL BUSINESS MACHINES CORPORATION
Application year: 1997
Main classification: G07F7
IPC codes: G07F7, H04L9, G06F21, G06F12, G06K19