Format-preserving cryptographic systems

• US 9,208,491 B2
• Filed: 12/02/2013
• Issued: 12/08/2015
• Est. Priority Date: 01/16/2007
• Status: Active Grant

• Current Assignee: entIT Software LLC (Open Text Corporation)
• Original Assignee: Voltage Security Incorporated (HP Inc.)
• Inventors: Spies, Terence, Pauker, Matthew J.
• Primary Examiner(s): Hewitt, II, Calvin L
• Assistant Examiner(s): Castilho, Eduardo
• Application Number:
  US14/094,354
• Publication Number:
  US 20140089203A1
• Time in Patent Office: 736 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 21/6227 where protection concerns the structure of data, e.g. records, types, queries
• CPC Class Codes: G06F 21/6245 Protecting personal data, e.g. for financial or medical purposes
• CPC Class Codes: G06Q 20/3823 combining multiple encryption tools for a transaction
• CPC Class Codes: G06Q 20/3829 involving key management
• CPC Class Codes: G06Q 20/401 Transaction verification
• CPC Class Codes: G06Q 2220/00 Business processing using cryptography
• CPC Class Codes: H04L 9/0618 Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/0866 involving user or device identifiers, e.g. serial number, physical or biometrical information, DNA, hand-signature or measurable physical characteristics
• CPC Class Codes: H04L 9/0869 involving random numbers or seeds
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853

Abstract

Key requests in a data processing system may include identifiers such as user names, policy names, and application names. The identifiers may also include validity period information indicating when corresponding keys are valid. When fulfilling a key request, a key server may use identifier information from the key request in determining which key access policies to apply and may use the identifier in determining whether an applicable policy has been satisfied. When a key request is authorized, the key server may generate a key by applying a one-way function to a root secret and the identifier. Validity period information for use by a decryption engine may be embedded in data items that include redundant information. Application testing can be facilitated by populating a test database with data that has been encrypted using a format-preserving encryption algorithm. Parts of a data string may be selectively encrypted based on their sensitivity.

Claims

1. A method for cryptographically processing credit card numbers, the method comprising:

obtaining, by a first application running on first computing equipment, a credit card number from another application;

sending, by the first application, over a communication network, to a key server a request for a key, wherein the request comprises a first identifier and a validity period;

receiving, by the first application, a key corresponding to the request from the key server;

by the first application, generating an index value corresponding to the validity period, encrypting the credit card number using the key, and generating a ciphertext using the encrypted credit card number and the index value;

transmitting, by the first application, the ciphertext to a second application on second computing equipment;

by the second application, extracting the encrypted credit card number and the index value from the ciphertext and retrieving the validity period using the extracted index value;

transmitting, by the second application, a second identifier and the validity period to the key server over the communication network, wherein the second identifier is equivalent to the first identifier;

receiving, by the second application, the key corresponding to the second identifier and the validity period; and

decrypting, by the second application, the encrypted credit card number using the received key.

2. The method defined in claim 1, further comprising:

by the first application, removing a checksum digit from the credit card number;

using an encryption engine implemented on the first computing equipment, encrypting the credit card number from which the checksum digit was removed;

by the first application, computing a new valid checksum for the encrypted version; and

by the first application, embedding a key selector into a checksum digit by combining the new valid checksum and the key selector.

3. The method defined in claim 2, wherein embedding the key selector into the checksum digit comprises adding the index value to the new valid checksum.

4. The method defined in claim 2, wherein encrypting the credit card number from which the checksum digit was removed comprises:

encrypting each digit of the credit card number from which the checksum digit was removed.

5. The method defined in claim 4, wherein encrypting each digit of the credit card number from which the checksum digit was removed comprises:

encrypting fifteen digits of the credit card number.

6. The method defined in claim 1, wherein encrypting the credit card number comprises encrypting the credit card number using a format-preserving encryption algorithm.

7. The method defined in claim 1, wherein obtaining the credit card number from the another application comprises obtaining the credit card number from a database.