Transaction security system

• US 4,755,940 A
• Filed: 01/06/1987
• Issued: 07/05/1988
• Est. Priority Date: 09/17/1983
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Matyas, Stephen M., Holloway, Christopher J., Oseas, Jonathan, Lennon, Richard E., Meyer, Carl H., Brachtl, Bruno
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/004,817
• Time in Patent Office: 546 Days
• Field of Search: 364/406, 364/408, 364/717, 364/200 MS File, 364/900 MS File, 235/379, 235/375, 235/380, 235/382, 340/825.34, 178/22.08, 178/22.09, 178/22.15, 380/24, 380/45, 380/47
• US Class Current: 705/44
• CPC Class Codes: G06Q 20/105 involving programming of a portable memory device, e.g. IC cards, "electronic purses"
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40 Authorisation, e.g. identification of payer or payee, verification of customer or shop credentials; Review and approval of payers, e.g. check credit lines or negative lists
• CPC Class Codes: G06Q 20/4012 Verifying personal identification numbers [PIN]
• CPC Class Codes: G06Q 20/4097 using mutual authentication between devices and transaction partners
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1016 Devices or methods for securing the PIN and other transaction-data, e.g. by encryption arrangements for secret communication, see H04L9/00

Abstract

An electronic funds transfer system (EFT) is described in which retail terminals located in stores are connected through a public switched telecommunication system to card issuing agencies data processing centers. Users of the system are issued with intelligent secure bank cards, which include a microprocessor, ROS and RAM stores. The POS includes a personal key (KP) and an account number (PAN) stored on the card when the issuer issues it to the user. Users also have a personal identity number (PIN) which is stored or remembered separately.

A transaction is initiated at a retail terminal when a card is inserted in an EFT module connected to the terminal. A request message including the PAN and a session key (KS) is transmitted to the issuers data processing center. The issuer generates an authentication parameter (TAP) based upon its stored version of KP and PIN and a time variant parameter received from the terminal. The TAP is then returned to the terminal in a response message, and based upon an imputed PIN, partial processing of the input PIN and KP on the card a derived TAP is compared with the received TAP in the terminal. A correct comparison indicating that the entered PIN is valid.

The request message includes the PAN encoded under the KS and KS encoded under a cross-domain key. Message authentication codes (MAC) are attached to each message and the correct reception and regeneration of a MAC on a message including a term encoded under KS indicates that the received KS is valid and that the message originated at a valid terminal or card.

Claims

1. A method of testing the validity of personal identification numbers (PIN) entered into an electronic funds transfer system (EFT) at a terminal connected through a data communication network to a data processing centre in which each user of the EFT system has an intelligent secure bank card on which is stored a personal key (KP) and a personal account number (PAN) and the data processing centre holds a master list of PINs and KPs or a logical function of PINs and KPs indexed by PANs, the method comprising the following steps:

1. generating a first transaction variant (Tterm) at the terminal whenever a transaction is initiated, and transmitting the first transaction variant to the card;

2. transmitting the PAN from the card and the first transaction variant (Tterm) to the data processing centre;

3. generating at the data processing centre a second transaction variant (Tiss) whenever a transaction message is received from a terminal;

3. A method as claimed in claim 1 in which the transaction variant includes a sequence number or time check portion and the data processor returns the transaction variant to the terminal with the transaction variant authentication parameter and the terminal performs a timeliness or sequence check on the returned message.

5. A method as claimed in claim 3 in which the transaction variant includes a random or pseudo-random number generated at the card logically combined with a random or pseudo-random number generated at the terminal.

2. generating a first transaction authentication parameter (TAP1) dependent upon the logical function of the associated PIN and KP and the first transaction variant (Tterm);

5. generating a second transaction authentication parameter (TAP2) dependent upon the first transaction authentication parameter (TAP1) and the second transaction variant (Tiss);

6. transmitting the second transaction authentication parameter (TAP2) and the second transaction variant (Tiss) to the terminal;

7. receiving from the card holder the PIN at the terminal and transmitting the PIN to the card;

8. generating at the card a first transaction variant authentication parameter based upon a logical combination of the entered PIN and the stored KP and the first transaction variant;

9. transmitting the card generated first transaction variant authentication parameter to the terminal;

10. at the terminal generating a second transaction variant authentication parameter dependent upon the first transaction authentication parameter received from the card and the second transaction variant received from the data processing centre;

11. comparing the terminal generated second transaction authentication parameter with the second transaction authentication parameter received from the data processing centre, a correct comparison indicating that the entered PIN was correct.

4. A method of authentication of a personal identification number (PIN) entered by one of a plurality of users at a terminal connected through a data communication network to a data processing center, each user having an intelligent secure card on which is stored a personal key (KP) and a personal account number (PAN) and the data processing center storing a master list of PINs and KPs accessible by PANs, the method comprising the steps of:

generating and storing at the terminal a transaction variant;

transmitting said transaction variant to said card and storing said transaction variant on said card;

transmitting the PAN from said card through said terminal to said data processing center, accompanied by said transaction variant;

generating at said data processing center by a one way encipher function, a transaction variant authentication parameter (TAP) directly dependent upon the PIN, the KP, and the transaction variant;

transmitting the TAP to the terminal and storing the TAP at the terminal;

receiving from said one of the plurality of users, the PIN at the terminal and storing the PIN on said card;

generating at said card a transaction variant authentication parameter (TAPc) directly dependent upon the entered PIN, the stored KP, and the stored transaction variant;

transmitting said TAPc from said card to the terminal and at the terminal comparing the TAP received from said data processing center with the TAPc received from said card, a correct comparison indicating that the entered PIN is valid.

6. A method as claimed in claim 4 in which the transaction variant includes a sequence number or time check portion and the data processor returns the transaction variant to the terminal with the transaction variant authentication parameter and the terminal performs a timeliness or sequence check on the returned message.

7. A method for maintaining secure communications between a user terminal and a central computer, wherein the user knows a memorized personal identification number (PIN) and carries in his possession a user card containing a personal account number (PAN) and a secret personal key value (KP) which remains in said card, the user card containing a microprocessor and a memory capable of communicating with the terminal when the user inserts the card into the terminal, the user initiating a transaction with the central computer by inserting the card in the terminal and entering his PIN number, the terminal including a secret terminal key (KMT) which it shares with the central computer, the method comprising the steps of:

generating a first random number (Tterm) at said terminal and transmitting it to said card to be stored thereon;

transmitting said PAN from said card to said terminal;

transmitting Tterm, PAN, and a terminal ID from said terminal to said central computer;

accessing a first data table stored in said central computer containing paired values of personal keys (KP) and personal identification numbers (PIN) for each authorized user of the system, assessible by said PAN;

generating at said central computer a second random number (Tiss);

generating at said central computer and transmitting to said terminal a centrally generated transaction authentication parameter TAP2 which is a function of Tterm, Tiss, KP and PIN, the values of KP and PIN being produced by said first table in response to said accessing step with said value of PAN;

transmitting from said central computer to said terminal said random numbers Tterm and Tiss, with Tterm enciphered under KMT, said terminal deciphering the enciphered Tterm under KMT and comparing it with the value of Tterm originally generated at the terminal, to insure that the terminal is receiving messages from the true central computer;

inputting by said user his PIN value into said terminal;

transmitting said PIN value from said terminal to said user'"'"'s card;

generating with said microprocessor on said user'"'"'s card a card generated transaction authentication parameter TAP1 from the values Tterm, KP and PIN, where the value of KP is provided by said user'"'"'s card and the value of PIN is provided by said user and transmitting said generated transaction authentication parameter TAP1 to said terminal;

generating on said card a test value transaction authentication parameter TAP2 which is a function of said generated value of TAP1 and the value Tiss and transmitting said test value of TAP2 to said terminal;

comparing in said terminal said centrally generated value of TAP2 from said central computer with said test value of TAP2 from said card;

authorizing said user to carry on his transaction using said card at said terminal with said central computer, if said comparison shows that the value of TAP2 from said central computer equals the value of TAP2 from said card;

denying authorization to said user to carry on a transaction with said card at said terminal to said computer center if said comparison shows that the value of TAP2 from said central computer does not equal the value of TAP2 from said card.