Patent Application
20170339111
Data masking, or redacting, is an important data management technology which prevents access to sensitive data by unauthorized users. Data masking may be applied to stored data at any time, applied when data elements are changed in the persistent data store, or applied to the data while it is in transit wherein data elements are changed while being transmitted to the data consumer.
Data masking techniques include masking data reversibly. Reversible data masking allows recovery of the original data from its masked representation. Data element encryption is an example of a reversible data masking technique. Irreversible data masking, alternatively, transforms the original data element in such way that its original content is wholly or partially lost. For example, one irreversible masking technique extracts a substring of a character string and replaces the remaining characters with arbitrary values.
Traditional data masking is not application friendly. When traditional data masking techniques, such as partial redacting, are applied the applications produce different results than they would with original unmasked data elements. This is especially so when sensitive data is syntactically defined as, for example, a formatted data string such as a driver's license number stored as a data element such as PA12345678, where the first two data element members represent the state of issue and is limited to a set of fifty two-letter state identifiers. In such a case, a masking that results in a data element ZX87654321 received by an application might result in errors during processing if the application expects one of the fifty state identifiers. Or for example, a query on a data set comprising data elements each having the first 12 digits of a credit card number masked (for example xxxx-xxxx-xxxx-1234) may produce different result than a query on an unmasked data set due to possible duplicate credit cards with same last four digits of the account number.
Format preserving encryption technology (“FPE”) exhibits certain desirable properties, but has difficulty (or is entirely incapable of) handling data elements having specialized format transform rules, and requires the management of sensitive cryptographic material. For example, a California license plate has a syntactically constructed format such that the first member of the California license plate is a digit between two and seven, the next three members are letters, and the last three members are digits between zero and nine. FPE is incapable of performing a semantically correct transformation of a complex data element such as a California license plate number due to the independence between the data object components. For example, the three letter code cannot be derived from the serial number value and vice versa. Any attempt to adjust the three letter code to achieve semantic correctness of the license plate number leads to the loss of original information during decryption or requires additional information stored in the database which effectively increases the size of the protected data objects in the database.
Accordingly, improvements are needed in systems for masking data while preserving formatting in a deterministic fashion such that each instance of an original data element when transformed by the data masking system under the same conditions results in the same masked data element having the same format.
While methods, apparatuses, and computer-readable media are described herein by way of examples and embodiments, those skilled in the art recognize that methods, apparatuses, and computer-readable media for generating masked data elements utilizing format preserving data masking are not limited to the embodiments or drawings described. It should be understood that the drawings and description are not intended to be limited to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims. Any headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used herein, the word “may” is used in a permissive sense (i.e., meaning having the potential to) rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.
Due to limitations of the traditional masking, an improved technique for providing a masking mechanism for preserving format of the original data element in order to attain robust results from business applications which operate on masked data is desirable. Applicant has discovered methods, apparatus, and computer-readable media for generating masked data elements from original data elements utilizing format preserving data masking. The disclosed methods, media and systems involve data object characterization by means of one or a plurality of attributes, such as data type, data position, one or more basis sets or alphabets, and security parameters. More specifically, the disclosed methods and systems involve processing sensitive data elements to mask sensitive data in a way that is transparent to a user and maintains the robust performance of applications which rely on the masked sensitive data, resulting in a more secure computing environment without negatively impacting the performance of the computing environment, and/or in a more secure computing environment while improving the performance of the computing environment over traditional masking techniques.
Applicant has discovered a novel approach to transforming data elements based on a syntactic characterization of a set of data elements to allow a computer to process the data elements in a different way. A syntactic characterization of a data object, for example a sensitive data object, is a way of describing the semantic format of a set of data elements of a same type, for example an ordered pair comprising values of a different type arranged in a particular ordering such as the California license plate number described above.
The present system utilizes a novel technology for preserving the format of an original data element, for example data element x, having a datatype X. When a masking procedure is applied to obtain a masked data element, for example masked data element x*, such that x, x*∈X, that is data element x and masked data element x* each are of a set of all elements having a data type X. In other words, the various embodiments disclosed herein provide a one way mapping F(x) of an element x to another element x* wherein x and x* have the same syntactically defined format.
The embodiments are not limited to a particular type of data element or a particular type of data type. A data element may take, without limitation, the form of continuous numbers, discontinuous numbers, strings, or symbols, any of which may also be subject to special conditions. A data element is comprised of a number of data element members in an ordered arrangement or a random arrangement. Each data element or data element member may be represented and stored according to any type of encoding such as hexadecimal, octal, decimal, decimal binary, binary numbers, binary numbers corresponding to ASCII values, combinations of decimal numbers stored as binary and letters numbers and symbols stored as ASCII values, or any combination of the above. It will be appreciated that any type of encoding may be used to represent the values comprising a data element as the data element is stored, as the data element is retrieved, as the data is communicated, as the data is processed and as the data is displayed to user. It will also be appreciated that the encoding of data elements may occur during the course of processing by necessity or by design to achieve efficiency in coding or system efficiency in implementation. It will also be appreciated that the various transformations of data during the course of storing, retrieving, processing, communicating etc. will all be handled by the various embodiments of the data masking system disclosed herein.
The embodiments can operate in a dynamic fashion applying data masking data elements as they are retrieved, communicated, or processed without the need to store intermediate values or masked values after they are needed, because each original data element will always result in the same format preserved masked data element under the same conditions. For example conditions can be the user, the users authorization, the users access level, the access level of the requesting application, the authorization level of the application or the machine one which the application is running, the instance of the data element, the database table in which the data element is stored, the database instance, or the particular deployment of the database. It will be appreciated that the types of conditions that might alter the masking of a data element are many and varied and not limited by those listed herein, but chosen by a system designer based on design specifications and costs including processing costs and costs associated with a data elements value among other things.
It will be further appreciated that the embodiments disclosed herein do not require any encryption schemes and are thus free of any restrictions associated with the use of encryption, while at the same time the masking capabilities provided by the data masking capabilities are equal to or exceed those data masking techniques that rely on encryption techniques, such as FPE, without the necessity of managing sensitive cryptographic information. It will also be appreciated that the data masking disclosed herein has significantly more flexibility than a comparable encryption based solution by virtue of unimpeded application of specialized format preserving transformation rules which are not possible with encryption based approaches.
Though the embodiments described herein are not reliant on encryption they are compatible with encrypted data while being independent of the encryption mechanisms in a particular system. Thus, the data masking mechanism disclosed herein allows separating the process of data objects encryption and format preserving presentation. In an exemplary implementation of this invention data objects in a database are encrypted using standard cryptographic methods such as AES encryption in Galois/Counter Mode (GCM) or, without limitation, in any other standard block cipher application mode while format preserving transformation is performed by a remote proxy service.
Though the description involves examples involving masking of a license plate number to demonstrate how a complex syntactically defined data element may be processed according to one or more embodiments, the disclosed methods, systems, and computer-readable medium can also be utilized to mask sensitive data elements of arbitrary data objects, such as bank account numbers, badge numbers, identification numbers, classification numbers, names, credit cards numbers, and the like.
First, an irreversible function 120 is applied to data element 110. The irreversible function is a one way function. The irreversible function 120 may be for example a hash function, a deterministic random bits generator (“DRBG”), or a pseudorandom number generator (“PRNG”). The irreversible function can for example be sha-256 or md5. It will be appreciated that any one way function may be used so long as it deterministically arrives at the same output for a given set of inputs, and the particular form of the irreversible function can be selected based on the security requirements of the system.
Irreversible function 120 when applied to data element 110 outputs a derivative data element 112. Depending on which one way function is chosen as the irreversible transform 120, the resulting derivative data element will comprise a fixed number of values encoded in a uniform format that typically will not be of the same data type as data element 110, that is the derivative data element 112 will not be syntactically defined in the same way as data element 110. Derivative data element 112 may, if for example the irreversible transform is md5, comprise for example thirty-two hexadecimal members encoded in binary digits, two hexadecimal digits to an octal, or alternatively it may be encoded as a string of thirty-two members each encoded in ASCII. Alternatively, for example, if the irreversible function 120 is adler32, the derivative data element 112 may be a string of eight values.
If a longer derivative data element 112 is desired, for example when using md5 as the irreversible function 120 resulting in a derivative data element comprising thirty-two member members but a given data element x is of data type X, having elements that comprise fifty data element members, the length in element members of the derivative data element can be increased for example by applying md5 to x and then hashing the result and concatenating the two values. For example the resulting derivative data value may be md5(x)∥md5(md5(x)). This process can be reiterated to obtain a derivative data value of at least any desired size.
A template 114 is selected 122 from a portion of the derivative data element 112. This selection of template 114 can be accomplished in any suitable manner. For example for a data element x 110 of length ten, i.e. L(x)=10, the selection of template 114 can be accomplished by selecting the first ten derivative data element members of the derivative data element 112 counting from the left. Alternatively the selection of template 114 can be accomplished by selecting the first ten derivative data element members from the right. Alternatively, the selection of template 114 can be accomplished by selecting the twenty-sixth through thirty-fifth derivative data element members from either the left or right. It will be appreciated that any suitable deterministic algorithm may be used to select a template 114 from derivative data element 112.
A masked data element 118 is then obtained by applying 124 a syntactic definition 101 to template 114. Syntactic definition 101 characterizes all elements of data type X in terms of one or more alphabets 102, a position map 104, and a set of conditions 106. For example, a California license plate issued after 1982, as discussed above, for example x=4SAM123 is syntactically defined by the format mSSSnnn, where m is taken from the alphabet of digits between 2 and 9, SSS is sequence of three characters taken from English alphabet, i.e. set of letters A-Z, and nnn is a three digit sequence of digits from 0 to 9. A special condition for California passenger vehicle license plate number is a gap in the character sequence: license plates 3YAA-3ZYZ series were not issued. Though simplified for brevity the above example thoroughly illustrates characterization of a data object type at hand.
In the case of the California license plate data element x, for example 110, having syntactic compound of the form mSSSnnn is of data type X, such that data element members xn for 0≦n≦6 are ordered in the form x6x5x4x3x2x1x0 where all elements of data type X comprise members of the form x6∈m, x5 x4 x3∈SSS, and x2 x1 x0∈nnn, where any xn comprises one octet for 0≦n≦6, for example x6∈m, comprises one octect of type m, it follows that SSS comprises three octets of type S, and nnn comprises three octets of type n; and for example, each octet is either an ASCII character or an 8 bit described binary number, such that x is a total of 7 octets. Each data element x of data type X comprises member data elements each of which is characterized by one of the following alphabets: x5, x4, x3∈S∈A1={ABCD . . . XYZ}; x2, x1, x0∈n∈Ax2={0123456789}; x6∈m∈A3={234567}. Thus the syntactic compound data element x, for example 110, expressed as data element members x6x5x4x3x2x1x0 of form mSSSnnn, is associated with a positional map that maps each data element member to an alphabet 102 for example positional map 104: x6x5x4x3x2x1x0∈A3 Ax2 Ax2 Ax2 A1 A1 A1. The syntactic compound word x of data type X, for example data element 110, additionally is associated with a set of conditions 106 (these special conditions allow for the discontinuities in the data element x), for example conditions 106 are: for x6=3∈A3, the following condition applies: x5x4x3<YAA or x5x4x3>ZYZ.
Applying 124 syntactic definition 101 to template 114 generates a masked data element 118 by converting the template to data type X by any suitable method. When one or more conditions 106 must be satisfied for masked data element 118 to conform to the syntactic definition, the conditions are then checked, at step 130, to determine that the conditions are satisfied. If the conditions are not satisfied, the result is an invalid masked data element 116. Irreversible function 120 is then applied to the invalid masked data element 116 and the system again carries out the method described above, and this is repeated until the conditions are satisfied, thus generating masked data element 118.
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Optionally, before applying the irreversible transform 314, data element of Type X 302 may be augmented by applying a unique salt value 316. This unique salt value may for non-limiting example be specific to a particular data object instance, a database table, a database, or a particular deployment among other things. For example, it may be the case that for security reasons a designer may want to preclude an unauthorized user or application from “seeing” that the same data entry, for example “John Smith,” exists in two separate databases. For example database A may be managed by a first company, and database B might be managed by a second company, and each of database A and database B might have the entry John Smith. It may be desirable that users or applications of each database should be precluded from knowing that each database A and B has a similar entry. Applying a unique salt 316 to the data element 302 before applying the irreversible transform 314 will ensure that derivative data element 304 of each implementation, or deployment, or instance, will be different.
Position map 418 characterizes all elements of data type X in terms of both the number of data element members of a data element, for example x 402, of data type X, and position map 418 characterizes all elements of data type X by specifying which alphabet, for example Ax1 412, Ax2 414, or Ax3 416, each data element member, for example data element member x6 422, is characterized by. Thus, data element x 402 comprises data element members x6x5x4x3x2x1x0, including seven distinct members where each value xn is a data element member, such as data element member x6 422, and the resulting data element x 402 is characterized by ordering each data element member xn according to the position map, thus to illustrate for x=4SAM123: x6=4∈Ax3, x5=S∈Ax1, x4=A∈Ax1, x3=M∈Ax1, x2=1∈Ax2, x1=2∈Ax2, x0=3∈Ax2, as is clearly set forth in position map 418.
Syntactic definition of data type X 410 includes a set of conditions 420. In this illustrative example, the disclosed embodiment data structure 400 includes conditions 420 in order to reflect the fact that California license plate numbers issued after 1982 exclude unissued license plates beginning with the following range of data element members 3YAA-3ZYZ, because California never issued a series of license plates beginning with the values 3YAA-3ZYZ. Thus one or more conditions 420 are required of a data element, for example 402, in order to accurately describe a data element in the set of all California license plates issued since 1982, for example data type X. One way of describing this condition is to express it as for a data element 402 having a data element member x6=3∈Ax3, the data element members x5x4x3 a must be less than the value YAA∈Ax1Ax1Ax1, or x5x4x3 must be greater than the value ZYZ∈Ax1Ax1Ax1. It will be appreciated that conditions may be described and imposed in any suitable manner. For example, one or more conditions 420 may be a checksum, or any other discontinuous range of values in an otherwise continuous set, or any condition that generally cannot be expressed in terms of a data element member position and corresponding alphabet.
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Thus at subprocess 760 the ASCII values are logically converted to their decimal values for performing operations on the values. Thus the representation of data element 704 comprising data element members 704a-704g corresponding to template 702, t=30dfa8d is logically represented at 706 as data element members 706a-706g in logical decimal as ‘51’ ‘48’ ‘100’ ‘102’ ‘97’ ‘56’ ‘100’. These values need to be mapped to a value within the desired alphabet, for example, 102, 412, 414, or 416, as described by the position map, for example (102 or 418), of the desired data type (corresponding to the data type of the original data element, for example 110, 302, 402, and 702). In this exemplary embodiment, to accomplish this mapping, modulo division is applied to each of the values 706a-706g where the basis modulo is determined by the length of the alphabet, for example 102, 412, 414, or 416, corresponding to the desired data element member as described by the relevant position map, for example 102 or 418.
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From intermediate result data element 708, at subprocess 880, each intermediate data element member 708a-708g is added to the first value of the corresponding alphabet as determined by the position map for the desired data type of the desired masked data element, for example 812. Recall that all data elements of data type X in this exemplary illustration are described by syntactic definition of data type X 410, including position map 418, which maps each element of data type X, for example masked data element x* 812, to a respective alphabet 412, 414, or 416. Thus the data element members of x* 812 are x*6x*5x*4x*3x*2x*1x*0 which correspond to positions 810a-810g in
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The various embodiments disclose consist of computer software code recorded on computer readable media and executed by one or more processors. Where the embodiments are disclosed in terms of their function in this description it is for the purpose of clarity of description, but need not be discrete devices or code portions, and may be integrated segregated or integrated in any particular manner. Various computer devices may be used to implement the embodiments such as servicers, PCs, mobile devices, laptop computers, tablets, handheld computing devices or various combinations of these devices. Furthermore, the embodiments need not be implemented in software code, but instead may be hardcoded into, for example, FPGAs, ASIC chips, customized processors, Stretch microprocessors, DSP chips, ARM processors, microprocessors, system on a chip based devices and the like.
Having described and illustrated the principles of our invention with reference to the described embodiment, it will be recognized that the described embodiment can be modified in arrangement and detail without departing from such principles. It should be understood that the programs, processes, or methods described herein are not related or limited to any particular type of computing environment, unless indicated otherwise. Various types of general purpose or specialized computing environments can be used with or perform operations in accordance with the teachings described herein. Elements of the described embodiment shown in software can be implemented in hardware, as discussed above, and vice versa.
In view of the many possible embodiments to which the principles of our invention can be applied, we claim as our invention all such embodiments as can come within the scope and spirit of the following claims and equivalents thereto
