GB2434014A

GB2434014A - Transaction verification using signed data combination

Info

Publication number: GB2434014A
Application number: GB0600350A
Authority: GB
Inventors: Clive Leader
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-01-10
Filing date: 2006-01-10
Publication date: 2007-07-11
Also published as: GB0600350D0

Abstract

A transaction verification system in which a PIN may be entered at a point of sale, signed by a payment card having secret keys in conjunction with other data (e.g. card details and transaction data) and the resulting cryptogram sent to a card issuer. The card details and transaction data are available to the card issuer separately, which then recalculates the cryptogram using a stored value for the cardholder's PIN, and the secret keys, also known by the card issuer. If the two cryptograms are equal, the PIN is determined to have been entered correctly and the user and transaction are validated. The PIN is not signed as an entity in isolation, and need not be stored on the card or securely transmitted in isolation.

Description

Page 1 Title Secure Infrastructure Free PIN Verification for Payment

Cards

Background

Current cardholder verification solutions for payments and other instructions using the Personal Identification Number, as documented in industry standards for example, require either: * For hardware encryption of the secret PIN information throughout the route from the point of interaction to the issuing agent where the PIN can be verified (known as on-line PIN), or * For the PIN to be stored securely on an IC card (known as off-line PIN), meaning special effort is required to manage the PIN on the card (for example supporting PIN change or resetting the PIN Try Counter when the PIN has been entered incorrectly too many times), and effort is required to authenticate the IC card as being genuine at the time of the transaction.

The provision of this secure infrastructure increases the cost of deployment and limits the types of transactions and environments where PIN verification can be used.

Supporting PIN offline on the chip card increases the complexity of a transaction, as the card must be proved to be genuine, increases the time required to complete a transaction and takes special effort and cost to manage the PIN on the card.

Statement of Invention

This invention relates to a process to verify a payment card user without the need to provide a secure infrastructure between the card and the issuing agent -either at the time of the transaction or to manage secret data on the card after personalisation.

This solution requires the PIN to be presented to the IC card (chip card) by the PiN Pad / interface device. The card signs the PIN data, together with other data relating to the transaction or generated by the card or terminal, as part of a general authentication cryptogram produced. The PIN is not signed as an entity in isolation.

The cryptogram can be passed through the terminal, networks and intermediate processing systems in clear (without being kept confidential) as the secret data (the PIN) is not transported and cannot be deduced from the cryptogram produced.

The recipient issuing bank or agent uses the card details, transaction information, secret keys and the correct PIN number to recalculate the cryptogram and match this with the value received. If this matching is correct then the correct PIN number must have been entered at the time of the transaction.

The issuing agent can establish the correct PIN was entered for the transaction without actually receiving the PIN number that was entered.

The patent application relates to the unique method of having the PIN verified by the overall solution, not the underlying technology of the payment transactions which are widely known and published. The patent does not assume any specific method for communicating the PIN to the IC card, any specific hashing or cryptographic process in the card or any specific validation process by the issuing agent. The patent relates to the inclusion of the PIN within a general transaction cryptogram produced by the Page 2 IC card removing the need to securely transport the PIN to the issuing agent or manage the PIN data on the IC card itself.

Advantages This invention overcomes the problems of the two current predominant solutions: * As the PIN is not transmitted as part of the information sent to the issuer, there is no need to keep the data confidential. Hence the cost and technical complexity of providing secure confidentiality is eliminated * As the PIN is not maintained on the card, there is no need to manage the confidential data on the card. This simplifies the personalisation process and avoids the need to provide a secure infrastructure to manage the PIN on the card, for example to allow the customer to change their PIN or to reset the PIN try counter if this is exhausted.

The invention does not require for the acceptance device to validate that the card is genuine as the issuer of the card or their agent will implicitly do this as the cryptogram is validated.

By combining the PIN with other data to produce a single digital signature the invention: * Reduces the risk of a third party being able to deduce the PIN from a number of genuine cryptograms * Makes it easier for existing systems to transmit the cryptogram to the card issuer or their agent as it does not introduce extra data or security requirements

Description

The following describes the process flow in which the solution will be used: * A cardholder desires to make a purchase or other transaction. Any underlying standard or process may be used for the integrity of the transaction * The cardholder is invited to enter their PIN number into any suitable PiN entry device. This could be a secure PIN pad attached to a terminal or a standalone handheld card reader with key pad or another type of device * The PIN is transmitted to the chip card is a suitable manner. This may be via a contact chip interface or a contactless interface. The security of the PIN in transfer to the chip card is not part of this invention * The chip card generates a cryptogram based on secret keys in the card (these may be derived for each transaction or static) and input data from the card and / or the terminal. The PIN value entered is included within the hash value signed by the card to create the cryptogram. The PIN is only a part of the information included in the hash which should include data that is unique to the current transaction. To link the cardholder verification to the specific transaction a unique reference or the transaction amount may be included. This invention does not define a specific hash algorithm or data input, but the data must be unique or sufficiently unpredictable to make it impossible to deduce the PIN from multiple transaction details Page 3 * The cryptogram (or a portion thereof) is transmitted to the card issuer or their agent. This data does not need to be kept secret during transmission (it could, for example, be spoken, sent over the internet, entered via a mobile phone text message, written down on paper or transmitted via a standard open network) * The issuer recreates the cryptogram based on the secret keys (known to them), the reference PIN number (known to them) and card details and transaction information included with the message or deduced by the issuer. The cryptogram is then matched to the complete or part cryptogram received * This validation proves that the genuine PIN number was entered at the point of interaction

Claims

Page 4 Claims I. a cardholder verification process whereby the PIN

number entered by the cardholder is cryptographically signed by the card, along with other transaction, terminal or card data and transmitted through any media to the issuer or their agent for verification
2. a cardholder verification process, as claimed in the proceeding claim, that enables the issuer of the card or their agent to verify that the correct PIN has been entered, without the need to transmit any confidential or secret information to the issuer or to store PIN information on the chip card
3. a cardholder verification process, as claimed in any proceeding claims, whereby the PIN number entered by the cardholder is cryptographically signed by the card, along with other transaction or card data using secret keys known to or derivable by the card issuer or their agent
4. a cardholder verification process, as claimed in any proceeding claims, which may be used across a variety of communications devices including mobile phones, set top boxes, fixed telephones or PCs linked to dedicated communications or via the internet
5. a cardholder verification process, as claimed in any proceeding claims, which does not require direct connectivity between the card reading device and the communications system to the issuer
6. a cardholder verification process, as claimed in any proceeding claims which may support a variety of transactions including access to restricted, secret or confidential information, making value payments, commercial transactions or contractual commitments