Patent Application
20120317036
This invention relates to online transactions, and more particularly, to ways to help secure sensitive data during online transactions.
Online transactions such as purchase transactions often require that entities such as merchants and payment card processors exchange sensitive information. For example, in connection with a typical purchase by a customer, a merchant may obtain the primary account number (PAN) corresponding to the payment card account of a customer (e.g., the customer's credit card number). The merchant may provide the PAN to a payment card processor (payment processor) as part of an authorization request. The payment processor may use a tokenization server to generate a corresponding token that is provided to the merchant if the purchase is authorized. Later, when settling the purchase transaction, the merchant may submit the token and the settlement amount to the payment processor. The payment processor may recover the PAN of the customer from the token.
Because the token can be used to settle the purchase transaction, the token should not be exposed to any unauthorized parties. In environments with numerous merchants or merchants with numerous sub-entities, it can be challenging to secure tokens, leading to potential security vulnerabilities.
It would therefore be desirable to be able to provide improved ways in which to handle sensitive data such as tokens in connection with online transactions.
A customer may provide a merchant with primary account number information for a payment card in connection with a purchase transaction. The merchant may send an associated authorization request to a payment card transaction processor. The authorization request may include information on a monetary value associated with the desired purchase transaction and the primary account number.
If the payment card processor determines that the customer is authorized to make the desired purchase, a tokenization server at the payment card processor may generate a token corresponding to the primary account number. To secure the token, the token may be encrypted at the payment card processor using a cryptographic key shared with the merchant.
A structure preserving encryption algorithm may be used in encrypting the token. A processor identifier or other information may be embedded in the encrypted version of the token during the structure preserving encryption operation. The merchant can use the shared key to decrypt the token and extract the processor identifier. A settlement request may be directed to the processor from the merchant to settle the transaction. The settlement request may include the decrypted version of the token and the monetary settlement amount associated with the purchase transaction. The merchant may use the processor identifier to direct the settlement request to the appropriate payment card processor.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.
Merchants authorize and settle payment card purchase transactions by communicating electronically with payment card processors. An illustrative system 10 in which payment card transactions may be authorized and settled is shown in
Steps involved in an illustrative purchase transaction using a system of the type shown in
A customer desires to make a purchase at merchant 12. To make the purchase, merchant 12 obtains the primary account number (PAN) associated with the payment card account of the customer (e.g., the customer's credit card number). For example, a magnetic card reader or other equipment at the merchant may be used to read the PAN from the customer's card. At step 24, the merchant may submit an authorization request to payment processor 14 over network 16 to determine whether the customer is authorized to make a purchase. The authorization request generally includes the PAN and a requested authorization amount. The authorization amount may be somewhat larger than the actual expected purchase price.
In response to receiving an authorization request, payment card processor 14 determines whether the customer is authorized to make a purchase of the requested amount. If authorized, processor 14 may return a token to the merchant that corresponds uniquely to the customer's PAN. Processor 14 may use tokenization server 18 to manage tokens during the operations of step 26. Tokenization server 18 may maintain database 20. Database 20 may contain a list of PANs and corresponding tokens. Each entry in database 20 may include a PAN and a unique token for that PAN. When presented with a PAN at step 26, tokenization server 18 may consult database 20 to determine whether an entry for that PAN already exists. If an entry is present, the tokenization server may retrieve the token associated with the PAN. If no entry is currently present for the PAN, tokenization server 18 may generate a token for the PAN and may store the generated token in database 20 for future use.
After obtaining a token for the PAN in the authorization request from tokenization server 18 during the operations of step 26, payment card processor 14 may return the token to merchant 12 for use in settling the purchase transaction (step 28).
At a later time, the merchant may settle the purchase transaction by submitting a settlement request to payment processor 14 (step 30). The settlement request may include the token and the final purchase transaction amount (i.e., a monetary value). The final purchase transaction amount may be equal to the previously authorized amount or may be different from the previously authorized amount. As an example, if authorization was requested for $500, the settlement amount may be for $134. In processing the settlement request during the operations of step 32, the payment processor may use tokenization server 18 to retrieve the PAN associated with the transaction based on the token. After processor 14 has processed the settlement request with a settlement process running on the computing equipment of processor 14 that uses the retrieved PAN, the merchant may be informed of successful completion of the purchase transaction over network 16.
It may be desirable to use encryption techniques to help secure sensitive data during purchase transactions. For example, it may be desirable to use format preserving encryption algorithms and structure preserving encryption algorithms to encrypt tokens such as the token provided to the merchant at step 28 of the flow chart of
In format preserving encryption schemes, strings may be encrypted using a format preserving encryption (FPE) process that preserves the format of the string. During decryption operations, a corresponding FPE decryption process may be used in decrypting the encrypted string. An example is shown in
The unencrypted version of the string (i.e., 2137 in the example of
Format preserving encryption algorithms may be used to encrypt and decrypt strings of any suitable format (e.g., strings whose valid characters are letters, mixtures of letters and digits, subsets of the letter characters, subsets of the digit characters, selected sets of letters, selected sets of digits, selected sets of characters that include mixtures of letters and digits, non-digit characters such as letters and/or non-letter characters, non-letter characters such as digits and/or symbols, symbols, non-symbol characters, etc.). As one example, an FPE process may be used to encrypt and decrypt strings having the format of CCDDD, where C represents upper and lowercase letter characters and where D represents digit characters.
An extension to FPE algorithms may be used that allows a string in a first format to be transformed into a string in a second format. For example, an all-digit string (DDDD) may be encrypted to produce a corresponding encrypted string with two leading digits and two trailing letter characters (DDCC). In this type of arrangement, which is sometimes referred to as structure preserving encryption (SPE) or format preserving encryption, it is not necessary for the first and second formats to be identical. Rather, the first and second formats may be arbitrarily selected when setting up the SPE process.
An example of an SPE process is shown in
The original and target character spaces may be of equal size or may be of different sizes. When the ciphertext strings are represented in a larger space than the plaintext strings, it is possible to embed information within the ciphertext as part of the encryption operation. In the illustrative arrangement of
Payment card processor 14 of illustrative system 10 of
In the illustrative system configuration of
Security may be enhanced by encrypting tokens so that a token cannot be used by an unauthorized party such an attacker associated with a merchant other than the intended recipient of the token or another unauthorized party. To ensure that tokens that are generated for one merchant cannot be used by personnel at another merchant or other unauthorized party, SPE process 22 can transform generally applicable (“global”) tokens that are generated by tokenization server 18 into merchant-specific tokens. In particular, SPE process 22 can convert a global token that is generated by tokenization server 18 for use by merchant A into a merchant-A-specific token by SPE-encrypting the global token using a key associated with merchant A. SPE process 22 can convert a global token that is generated by tokenization server 18 for use by merchant B into a merchant-B-specific token by SPE-encrypting the global token using a key associated with merchant B. SPE process 22 can likewise derive additional merchant-specific tokens using additional keys.
Merchants 12 can use corresponding SPE processes (and merchant-specific keys that are shared with the processor) to decrypt the encrypted version of the token. The decrypted version of the token may then be provided from the merchant to the processor during settlement requests. The processor can detokenize the decrypted version of the token using its tokenization server.
In some system configurations, merchants (e.g., large organizations) may wish to secure tokens so that respective sub-entities (e.g., offices, stores, branches, or other portions of a merchant's business) each receive tokens that have been individually encrypted. As shown in system 10 of
In illustrative system 10 of
When tokenization server 18 generates tokens for merchant A, SPE process 22 may encrypt the tokens using a key that is specific to merchant A (i.e., keyA). When tokenization server 18 generates tokens for merchant B, SPE process 22 may encrypt the tokens using a token that is specific to merchant B (i.e., keyB). SPE process 22′ may be used to further customize a merchant-A-specific token that is produced at the output of process 22. For example, the output of process 22 (i.e., the encrypted version of the token from server 18) can be encrypted using keyA1 to produce tokens specific to sub-entity A1, can be encrypted using keyA2 to produce tokens specific to sub-entity A2, and can be encrypted using keyA3 to produce tokens specific to sub-entity A3.
If desired, SPE processes such as processes 22 and 22′ of
Consider, as an example, illustrative system 10 of
Each processor 14 in system 10 of
To enhance efficiency, it may be advantageous for a merchant that has relationships with multiple processors to be provided with information that identifies which processor was used to provide each token. In this way, merchants can avoid providing settlement requests to settlement processes 14 at incorrect payment processors. The information that identifies the processor (e.g., a processor ID) may be embedded within each token using an SPE encryption process, as described in connection with
At step 37, one of merchants 12 (i.e., merchant “X”) may obtain a PAN of a customer (e.g., using a payment card magnetic stripe reader or other suitable computing equipment). The PAN and information on the monetary value of the desired payment transaction contemplated by the customer may be gathered in connection with an online purchase, in connection with a purchase at a brick-and-mortar establishment, or in connection with other suitable payment activities.
At step 38, computing equipment at the merchant may be used to formulate an authorization request with one or processors 14 (e.g., processor “Q”). Merchant X may be, for example, merchant A or merchant B of
At step 40, the processor may use the PAN to determine whether the customer's account has sufficient credit available and to otherwise determine whether or not the customer is authorized to complete the desired transaction. If the customer's PAN is authorized, the processor may tokenize the PAN using the tokenization server 18 at the processor. The tokenization server 18 may generate a global token (step 40).
At step 42, the SPE process 22 at the processor may convert the token from the tokenization server into a merchant-specific token. In particular, processor 22 may use SPE process 22 to perform an SPE encryption operation on the token from the tokenization server. The SPE encryption operation may optionally include a data embedding operation in which a processor ID that identifies the processor or other suitable information is embedded into the encrypted version of the token from the tokenization server. For example, a processor ID that identifies processor “K” may be embedded into encrypted versions of tokens generated by processor K. The SPE encryption process 22 that is used in encrypting the token preferably uses an appropriate cryptographic key. For example, the SPE encryption process at merchant Q (e.g., merchant K) may use a key (e.g., keyA) that is shared with the merchant (e.g., merchant A) for which the token is being encrypted. Keys such as keyA may be shared during system setup operations (e.g., over network 16, via physical delivery on a memory device, using identity-based encryption key sharing techniques, or using other suitable key sharing techniques).
Merchant X (e.g., merchant A) may receive the encrypted version of the token at step 44 and may decrypt the token using an appropriate key (e.g., keyA) and SPE process 22 at merchant X. As described in connection with
At step 48, the settlement process at the processor can use the tokenization server at the processor to detokenize the received token and thereby determine the PAN that corresponds to the received token. The PAN and the monetary value from the settlement requests may then be used by the settlement process in settling the payment transaction.
The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.
