1. Field of the Invention
The present invention relates to a system and method for validating or confirming information.
2. Background of the Invention
Many occasions arise when validation or confirmation of information is desired before taking a particular action. For example, a person may want to confirm that an address is a valid address before sending a valuable item or sensitive information to the address. As another example, a delivery business may want to confirm an address before sending a product. There are also occasions when validating an address can be lifesaving. For example, fire departments, ambulance companies, and police departments may want to confirm an address to efficiently respond to an emergency. There are times when other types of information, besides addresses, need to be validated or confirmed. For example, a traffic officer may need to confirm that a driver's license is valid before permitting a person to drive.
Despite the need to validate or confirm information, in today's information technology age, businesses and individuals are concerned about privacy and information security. Furthermore, businesses consider information to be a valuable company asset. Because of the concerns about information security and the view that information is an asset, owners of information may want to keep their information private and secure. On the other hand, an owner of information may also want to exploit the information by providing the information to others. For example, an owner of information comprising a list of all persons with access to a building may want to provide the list to a security company so that the security company may confirm whether a person seeking entrance into the building is on the list. However, for privacy reasons, the owner may not want to reveal to the security company all persons on the list. That is, the owner may feel that the list should only be revealed one person at a time as a person seeks entrance to the building. If a person on the list never seeks entrance to the building, then the security company never needs to know that the person is on the list. Based on the above concerns, it would be advantageous if an owner of information could provide the information to others for inquiry purposes, the information being in an encrypted format so that information may remain confidential.
In accordance with the invention, there is provided a method for representing a list of items using a bit array wherein each bit in the bit array is initialized to a first value. The method comprises converting each item into a N-bit object and determining bit positions based on the N-bit object. The method further comprises setting bits of the bit array to a second value at the determined bit positions.
There is further provided a method for determining whether an inquiry item is on a list of items. The list of items is represented by a bit array having first and second values. The method comprises converting the inquiry item into a N-bit object in a same manner that an item on a list of items is converted to produce a bit array representing the list of items. The method further comprises determining bit positions based on the N-bit object in a same manner that bit positions are determined for producing the bit array. Still further, the method comprises determining that the inquiry item is on the list if the bits of the bit array equal a second value at the determined bit positions and determining that the inquiry item is not on the list if at least one bit of the bit array does not equal a second value at the predetermined bit positions.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Systems and methods consistent with the present invention encode a list so that users of the list may make inquires to the coded list without the entire content of the list being revealed to the users.
Each item 102 in the list 105 turns on one or more bits in the bit array 110. That is, initially all the bits in the bit array 110 are low and are changed to high based on an item 102 in the list 105. More specifically, each item 102 in the list 105, once encoded by encoder 107, indicates which bit or bits to turn on in the bit array 110 to represent the item 102. For example, the first item 102 in the list 105 may turn on bits 1, 3, 11, as shown in
Each item 102 may turn on one or multiple bits in the bit array 110. In the example above, each item 102 turns on three (3) bits. However, a greater or lesser number of bits may be turned on for each item 102. The number of bits to turn on may be chosen to reduce the number of false positives that may result when a user makes an inquiry to the list 105, as discussed in greater detail below.
Once the encoder 107 has encoded each item 102 in the list 105, a bit array 110 with high and low values is used to represent the items 102 in the list 105. The bit array 110 may then be used by third parties for inquiry purposes without the content of the list 105 being revealed. Referring to
The inquiry item 202 undergoes the same encoding process that an original list item 102 undergoes. That is, the validation system 207 executes the same encoding process executed by the encoder 107. Recall that for the original list items 102, the encoder 107 determines which bits of the bit array 110 to turn on. For an inquiry item 202, the validation system 207 determines which bits of the bit array 110 to check. If all the bits checked are high, then the inquiry item 202 is determined to be part of the list. If at least one of the bits checked is low, then the inquiry item 202 is determined not to be part of the original list 105. For example, assume that that the validation system 207 processes the inquiry item 202, determining which bits to check. In
The standardizer 310 converts an input into a standard format prior to encoding. This step may be desirable for a list that may contain multiple variations of the same information. For example, a list that contains addresses may have multiple entries of the same address in different formats. It may be more efficient to encode a single representation of the same item than to encode each variation of the item. For instance, assume that multiple variations for an address are provided on a list. The entries include: 123 Main Street, Apartment 456; 123 Main St., Apt. 456; and 123 Main St., #456. The standardizer 310 may convert each of these entries to 123 Main St. 456 and encode this representation of the address rather than encoding each variation of the address.
The standardizer 310 may standardize a list in accordance with the teachings disclosed in the Provisional Application No. 60/277,622 entitled, “A Method For Standardizing A Mailing Address, Enhanced Modified Delivery Point”, by Robert Snapp, filed on Mar. 22, 2001, which is incorporated by reference. The provisional application discloses a method for standardizing a mailing address into a numeric string. As shown in
Once a list item 102 is standardized, it is input to the hashing function unit 320. The hashing function unit 320 may execute a one-way hash function, i.e., a function that transforms an input item making it difficult to impossible to reproduce the input. For example, a one-way hash function may take an input and produce an N-bit object having no obvious relationship to the input. Furthermore, a hash function may produce significantly different outputs for similar, but not identical, inputs. In an exemplary embodiment, the hashing function unit 320 executes a secure hashing algorithm, SHA-1, which was developed by the National Institute of Standards and Technology (NIST) and is an ANSI standard encryption technique.
The SHA-1 transforms an input into a 160-bit (20 byte) object called a message digest. The SHA-1 sequentially processes blocks of 512 bits when computing the message digest. Therefore, the SHA-1 pads an input bit string to produce a bit string with a length that is a multiple, n, of 512 prior to processing the input bit string. The SHA-1 pads the input bit string by appending a “1” to the input bit string, followed by a number of “0”s depending on the original length of the input bit string, followed by a 64-bit integer representing the original length of the input bit string. The number of “0”s appended to the input bit string equals a number which will produce a bit string with a length that is a multiple of 512 once the “1”, the “0”s, and the 64-bit integer is added to the input bit string. For example, to pad an input bit string with a length of 40, a “1” is appended to the input bit string, followed by 407 “0”s, followed by a 64-bit integer representing the length of the input bit string (i.e., 40).
The padded input bit string is viewed as a sequence of n blocks M1, M2, . . . , Mn, where Mi contains 16 words. Constant words K0, K1, . . . , K79 are used in the SHA-1, where, in hex:
Kt=5A827999 (0≦t≦19)
Kt=6ED9EBA1 ((20≦t≦39)
Kt=8F1BBCDC (40≦t≦59)
Kt=CA52C1D6 (60≦t≦79)
To generate the 160-bit message digest, the SHA-1 processes the blocks, Mi, for i=1, . . . , n. For each block, Mi, the SHA-1 computes constants words H0, H1, H2, H3, and H4. Initially, for block Mi, H0=67452301, H1=EFCDAB89, H2=98BADCFE, H3=10325476, and H4=C3D2E1F0 (all in hex). Hj for j=0, 1, 2, 3, 4 for subsequent blocks, Mi, initially equals the Hj computed for the previous block. The H0, H1, H2, H3, and H4 computed for block Mn is the 160-bit message digest.
Each block, Mi, is processed in the following manner. First, block Mi is divided into 16 words, W0, W1, . . . , W15. In addition, the following variables are initialized: A=H0, B=H1, C=H2, D=H3, and E=H4. For t=0 to 79, the SHA-1 computes the following equations:
TEMP=S5(A)+ft(B,C,D)+E+Wt+Kt
E=D; D=C; C=S30(B); B=A; A=TEMP
where:
Sn(X) is a circular shift of X by n positions to the left
ft(B,C,D)=(B^C)v(˜B^D) (0≦t≦19)
ft(B,C,D)=B XOR C XOR D (20≦t≦39)
ft(B,C,D)=(B^C)v(B^D)v(C^D) (40≦t≦59)
ft(B,C,D)=B XOR C XOR D (60≦t≦79)
Wt=S1(Wt-3 XOR Wt-8 XOR Wt-14 XOR Wt-16) (16≦t≦79)
X^Y=bitwise logical “and” of X and Y
XvY=bitwise logical “inclusive-or” of X and Y
X XOR Y=bitwise logical “exclusive-or” of X and Y
˜X=bitwise logical “complement” of X
X+Y=(x+y) mod 232 converted to a word, where x is the integer of X and y is the integer of Y.
After the above equations have been computed, Hj is computed as follows:
H0=H0+A
H1=H1+B
H2=H2+C
H3=H3+D
H4=H4+E
As stated above, the H0, H1, H2, H3, and H4 computed for block Mn is the 160-bit message digest.
The extraction circuit 330 extracts multiple n-bit samples from the N-bit object input from the hashing function unit 320. If the size of the bit array 110 is equal to 2x bits, then the size of each sample extracted from the N-bit object should be equal to or greater than x bits. The number of samples to extract from the N-bit sample may correspond to the number of bits that are turned on during the encoding process for each list item 102. In the case of the SHA-1, for example, the extraction circuit 330 may extract nine (9) 32-bit samples from the 160-bit object input from the hashing function unit 320.
The offset circuit 340 determines which bits in the bit array 110 to turn on based on the n-bit samples from the extraction circuit 330. Each n-bit sample turns on a bit in the bit array 110. Therefore, in
The encoder 107 may be implemented in software, firmware, hardware, or any combination thereof. The bit array 110 may be stored in any semi-permanent or permanent holding place for digital data, such as a magnetic disk (e.g., floppy disk or hard disk), optical disk (e.g., CD, CD-ROM, DVD-ROM), or magnetic tape.
As discussed above, the size of the bit array 110 or the number of bits the encoder 107 turns on may be chosen to reduce the number of false positives that may result when a user makes an inquiry to the list 105. False positives result when the validation system 207 returns an affirmative response although an inquiry item 202 is not on the list 105. This occurs because all the bits checked by the validation system 207 for the inquiry item 202 coincidentally where turned on by one or more other list items 102 during the encoding process. The probability of a false positive equals
where M equals the number of bits in the bit array 110, S equals the total number of bits turned on in the bit array 110, and k equals the number of bits the encoder 107 turns on per list item 102. Furthermore, S, the total number of bits turned on in the bit array 110, is approximately equal to
where N equals the number of list items 102. M, the number of bits in the bit array 110, and k, the number of bits turned on per list item 102, may be chosen to minimize the number of false positives based on the above equations. However, a higher false positive rate above the minimum may be chosen based on other considerations such as processing speed.
When an inquiry is made to determine whether an inquiry item 202 is on a list, it may be desirable to standardize the inquiry item 202 prior to determining whether the inquiry item 202 is on the list. If an inquiry item 202 is not standardized, the validation system 207 may incorrectly determine that the inquiry item 202 is not on the list simply because it is in a different format. The standardizer 510 may eliminate this problem by converting the inquiry item 202 into a standard format prior to validating. The standardizer 510 may operate in a same manner as the standardizer 310. Once an inquiry item 202 is standardized, it is input to the hashing function unit 520.
The hashing function unit 520 executes the same one-way hash function that is executed by the hashing function unit 320, generating an N-bit object. The N-bit object is input to the extraction circuit 530.
The extraction circuit 530 extracts multiple n-bit samples from the N-bit object in the same manner that the extraction circuit 330 extracts multiple n-bit samples. The multiple n-bit samples extracted by the extraction circuit 530 are input to the offset circuit 540.
The offset circuit 540 determines which bits in the bit array 110 to test based on the n-bit samples from the extraction circuit 530. The offset circuit 540 makes this determination in the same manner that the offset circuit 340 determines which bits in the bit array 110 to turn on. The validation system 207 tests the bits indicated by the offset circuit 540. As discussed above, if the bits tested are all high, then the validation system 207 determines that the inquiry item 202 is on the list 105; if at least one of the bits is low, then the validation system 207 determines that the inquiry item 202 is not on the list 105.
The validation system 207 may be implemented in software embodied locally in a workstation or in a server as shown in
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This is a continuation of, and claims the benefit of, U.S. patent application Ser. No. 10/344,990, filed Feb. 20, 2003, now U.S. Pat. No. 7,302,582 which was the National Stage of International Application No. PCT/US01/26125, filed Aug. 21, 2001, which claims the benefits of U.S. Provisional Application No. 60/226,568, filed Aug. 21, 2000, U.S. Provisional Application No. 60/277,622, filed Mar. 22, 2001, and U.S. Provisional Application No. 60/281,411, filed Apr. 5, 2001, all of which are incorporated herein by reference.
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