(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property
`Organization
`
`International Bureau
`
`(43) International Publication Date
`17 June 2004 (17.06.2004)
`
`PCT
`
`(10) International Publication Number
`WO 2004/051585 A2
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`(51) International Patent Classification7:
`
`G07F 7/10
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`(21) International Application Number:
`PCT/US2003/037928
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`(22) International Filing Date:
`26 November 2003 (26.11.2003)
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BW, BY, BZ, CA, CH, CN, CO, CR,
`CU, CZ, DE, DK, DM, DZ, EC, EE, EG, ES, FI, GB, GD,
`GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR,
`KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN,
`MW, MX, MZ, NI, NO, NZ, OM, PG, PH, PL, PT, RO, RU,
`SC, SD, SE, SG, SK, SL, SY, TJ, TM, TN, TR, TT, TZ, UA,
`UG, UZ, VC, VN, YU, ZA, ZM, ZW.
`
`(25) Filing Language:
`
`'
`_
`(26) Publlcatlon Language:
`.
`.
`(30) Pmmy Data:
`60/429,754
`
`English
`
`'
`English
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`27 November 2002 (27.11.2002)
`
`US
`
`(71) Applicant: RSA SECURITY INC [US/US]; 174 Middle—
`sex Turnpike, Bedford, MA 01730 (US).
`
`(84) Designated States (regional): ARIPO patent (BW, GH,
`GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW),
`Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European patent (AT, BE, BG, CH, CY, CZ, DE, DK, EE,
`ES, FL FR, GB, GR, HU, IE, IT, LU, MC, NL, PT, RO, SE,
`SI, SK, TR), OAPI patent (BF, BJ, CF, CG, CI, CM, GA,
`GN, GQ, GW’ ML, MR, NE, SN, TD, TG).
`
`
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`2004/051585A2||||||||H||||H|||l||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||l
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`PubHShed:
`(72) Inventors: JAKOBSSON, Markus; 1203 Garden Street,
`Hoboken, NJ 07030 (Us). JUELS, Ari; 131 Freeman — without international search report and to be republished
`Street, Brookline, MA 02446 (US). KALISKI, Burton,
`”P0" ”66"!” (WW ”PO”
`S., Jr.; 22 Pembroke Road, Wellesley, MA 02181 (US).
`
`(74) Agent: PRAHL, Eric, L.; Hale and Dorr LLP, 60 State
`Street, Boston, MA 02109 (US).
`
`For two-letter codes and other abbreviations, refer to the ”Guid—
`ance Notes on Codes and Abbreviations” appearing at the begin—
`ning of each regular issue of the PCT Gazette.
`
`(54) Title: IDENTITY AUTHENTICATION SYSTEM AND METHOD
`
`(57) Abstract: A method and system for generating an authentication code that depends at least in part on a dynamic value that
`changes over time, an event state associated with the occurrence of an event, and a secret associated with an authentication device.
`By generating the authentication code responsive to an event state, an identity authentication code can be used to verify identity and
`to communicate event state information, and to do so in a secure manner.
`1
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`VISA — EXHIBIT 1113
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`VISA - EXHIBIT 1113
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`WO 2004/051585
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`PCT/U52003/037928
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`IDENTITY AUTHENTICATION SYSTEM AND METHOD
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`Cross Reference to Related Applications
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`[0001]
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`This application claims the benefit under 35 U.S.C. § 119(e) ofU.S. Provisional
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`Application No. 60/429,754, filed November 27, 2002.
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`Field of the Invention
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`[0002]
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`The invention relates generally to the fields of cryptography and security. More
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`specifically, the invention relates to the generation and verification of identity authentication
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`codes.
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`Background of the Invention
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`[0003]
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`Generally, security systems employ identity-based authentication schemes to verify
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`the identity of an entity that is allowed access to a physical location or object, in the case of a
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`physical security system, or electronic access to a computer system or data, in the case of a data
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`security system. One goal of such security systems is to accurately determine identity so that an
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`unauthorized party cannot gain access. Security systems can use one or more of several factors,
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`alone or in combination, to authenticate entities. For example, identification systems can be
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`based on something that the entity knows, something the entity is, or something that the entity
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`has.
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`[0004]
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`Examples of something an entity knows are a code word, password, personal
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`identification number (“PIN”) and the like. One exemplary computer-based authentication
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`method involves the communication of a secret that is specific to a particular entity or user. The
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`entity seeking authentication transmits the secret or a value derived from the secret to a verifier,
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`which authenticates the identity of the entity. In a typical implementation, an entity
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`communicates both identifying information (e.g., a user name) and a secret (e.g., a password) to
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`the verifier. The verifier typically possesses records that associate a secret with each entity. If
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`the verifier receives the appropriate secret for the entity, the entity is successfully authenticated.
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`If the verifier does receive the correct secret, the authentication fails.
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`[0005]
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`Examples of something the entity is include characteristics that are unique to people,
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`such as physical, biological, and psychological characteristics (referred to generally here as
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`biological characteristics), such as fingerprints, handwriting, eye retina patterns, and face, body,
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`and organ appearance, size and shape. Suitable biological characteristics typically are not under
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`the control of the person, and are therefore difficult for anyone besides the intended person to
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`present, because, in part, they are difficult to replicate. The verifier typically can observe the
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`characteristic, and compare the characteristic to records that associate the characteristic with the
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`entity. The observation of biological characteristics is referred to generally as biometric
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`measurement.
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`[0006]
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`An example of something an entity possesses is a physical or digital object, referred
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`to generally as a token, that is unique, or relatively unique, to the user. A simple example is a
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`conventional metal key for use in a door. Possession of the door key in effect authenticates the
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`user to the lock and allows entry. Similarly, possession of a token such as a bank card having
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`certain specific physical and electronic characteristics, for example containing a specific
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`identification number that is revealed when the token is accessed in a particular manner, can be
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`this type of factor. A token containing a computing device that performs encryption using an
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`encryption key contained in the device would also be regarded as this type of factor. For
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`example, a token could accept user input, which might include a PIN or a challenge value, and
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`provide as output a result encrypted With a secret encryption key stored in the card. The verifier
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`can then compare the output to an expected value in order to authenticate the entity.
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`[0007]
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`A token might also, or alternatively, use additional input information, such as time, or.
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`a counter, for example, such that the result changes over time but is deterministic to an entity that
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`possesses a secret (e.g., a value known only by the token and the verifier), but not predictable by
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`an observer who does not possess the secret. These systems generally perform some
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`computation using a stored secret as input to generate an authentication code that is used to
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`authenticate the entity. Some systems are time-based, in that they use a time-based dynamic
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`variable to calculate a non-predictable authentication code that ultimately authenticates the
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`entity. Here, “non—predictable” means that the authentication code is not predictable by a party
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`that does not know the associated secret, the algorithm for calculating the code, or both. One
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`example, US. Patent No. 5,937,068 entitled “System and Method for User Authentication
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`Employing Dynamic Encryption Variables,” uses as input a combination or subset of three
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`variables: the current time, the number of access requests made by the card, and a “secret
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`dynamic encryption key” that is updated with each access request. The token, in this case, also
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`verifies a PIN entered by the user before communicating an authentication code.
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`[0008]
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`Although the dynamic nature of the authentication codes generated by such an
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`approach avoids problems inherent with using fixed authentication codes, an unattended or
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`stolen token remains vulnerable to attack. Would-be attackers who gain access to tokens can
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`subject the tokens to sophisticated analysis intended to determine their methods of operation,
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`and/or the secret(s) stored within. Attackers might inspect the token and conduct such analysis
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`in order to determine the associated secret, the algorithm for calculating the authentication code,
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`or both. The attacker might then be able to generate apparently valid authentication codes in
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`order to illegally gain physical or electronic access to secured areas or systems. Many tamper-
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`resistant hardware designs are available, however, new attacks are frequently developed to
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`thwart tamper resistance. Further, current tamper resistant designs do not provide verifiers,
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`authentication systems, system administrators, or another relevant authority with any indication
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`that the token has been tampered with.
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`[0009]
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`One approach to detection of tampering is described in Johan Hastad, Jakob Jonsson,
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`Ari Juels, Moti Yung, “funkspiel schemes: an alternative to conventional tamper resistance”,
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`ACM Conference on Computer and Communications Security 2000; 125—133. Hastad et al.
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`describe several “funkspiel schemes” whereby a device can indicate to a verifier that tampering
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`has occurred, without revealing to an adversary Whether the tampering has been detected. The
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`schemes are oriented toward the generation of a sequence of message authentication codes,
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`Where the message authentication may fail after tampering has been detected. In one example
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`given, the message authentication code is embedded into a digital signature scheme, where the
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`digital signature indicates whether a transaction has been approved by a device, while the
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`message authentication code indicates whether the device has been tampered with. The message
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`authentication code itself may not be suitable as an identity authentication code as it is oriented
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`toward a sequence of message transactions rather than time-based identity authentication. In
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`particular, Hastad et a1 does not provide any method for efficiently verifying a single
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`authentication code among those over a very long period of time, without substantial
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`computation by the verifier (e. g., a potentially long chain of function evaluations), substantial
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`computation by both parties (e. g., asymmetric encryption) or substantial storage by both parties
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`(e. g., many one-time bits).
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`Summary of the Invention
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`[0010]
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`The invention addresses these shortcomings by including an indication of the
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`occurrence of an event directly into the efficient computation of an identity authentication code,
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`where the verifier may efficiently verify the authentication code and identify the signaling of an
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`[0011]
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`While the previous approaches do not have the flexibility to communicate event
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`information in, or as part of, an authentication code, in the present approach, an authentication
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`code is generated in a manner that communicates to the verifier information about the occurrence
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`of one or more reportable events. A reportable event is an event other than events associated
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`with the normal operation of an authentication method (and that can be reported to the verifier).
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`Thus, for example, a reportable event would not include an event reporting a request for an
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`authentication code. A reportable event could be, on the other hand, an event that is at least one
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`of an anomalous, extraordinary, remarkable, unusual, and the like. A reportable event also could
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`be any sort of event that can be detected and/or communicated by or to the device. Example
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`reportable events include: device tampering; an event external to the device detected by the
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`device; an environmental event, such as temperature exceeding or falling below a threshold;
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`static discharge; high or low battery power; geographic presence at a particular location;
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`confidence level in a biometric reading; and so on. A reportable event may also provide an
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`indication of the likelihood that the security of the authentication system has been compromised
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`or the likelihood that the authentication device has or will develop an operational problem (e.g.,
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`the condition of the authentication device). A reportable event can be the cumulative effect of
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`multiple past events. A reportable event also can be the device operational status.
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`[0012]
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`A reportable event may include information concerning the condition of the
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`authentication device (cg, tampering, low battery power, etc.), the security of the authentication
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`system (e.g., strength of a user’s biometric information, accuracy of a PIN entry, verification of
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`an authentication device signature), the status of the user (e.g., mobile or stationary, network
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`access location, location in a facility, etc), the location of the device (e.g., region, country, city,
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`etc.) or the environment where the device is located (e.g., temperature, radiation level, etc.). In
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`one embodiment, the reportable event directly reports information concerning at least one of the
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`condition ofthe authentication device, the security of the authentication system, the status of the
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`user, the location of the authentication device, and the environment where the authentication
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`device is located.
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`[0013]
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`In general, in certain aspects of the invention, a user or a device on behalf of the user,
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`algorithmically computes an authentication code based on both a dynamic variable (e.g., that
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`changes over time) and a secret associated with the user or the device. The generated
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`authentication code is non-predictable to an observer, but is verifiable by a verifier. The
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`authentication code can also depend, in part, on any other information, for example, on one or
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`more of a PIN, a password, and data derived from a biometric observation, or information
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`associated with the user, the authentication device, or the verifier.
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`[0014]
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`The security of an authentication system is improved when a device takes specific
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`action upon the occurrence of a reportable event. In one illustrative example, if an attacker
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`attempts to disassemble or otherwise tamper with a device, it is useful for the device to signal the
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`occurrence of such event (once detected by the device) to a verifier by communicating the
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`device’s event state. In this example, the tampering event has at least two possible event states;
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`yes — tampering occurred, and no — tampering has not occurred. Other information also can be
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`communicated, such as information about the type of tampering or information about the time
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`that the tampering occurred. Other examples of reportable events include environmental events
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`(e.g., high or low temperature), battery voltage level, and accuracy of PIN or password entry.
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`[0015]
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`In one embodiment, the occurrence of an event is communicated explicitly in the
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`authentication code. For example, one or more bits included in the authentication code can be
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`dedicated to reporting the occurrence of an event, i.e., reporting the event state (and herein we
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`refer to event state data as data representing, communicating, or derived from the event state)
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`Where the event state is information about the state of a device with respect to the occurrence or
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`non-occurrence of event(s). In another embodiment, the device’s event state can be
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`communicated implicitly, such that only the device and the verifier can feasibly determine the
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`event state from the communication. It may be advantageous if an attacker with access to device
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`is unable to determine if an event was detected and communicated because an unwamed attacker
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`is more likely to take actions that can lead to observation and apprehension by authorities. In
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`some embodiments, the device operates differently upon occurrence of an event, such that the
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`occurrence of the event is communicated in identity authentication codes output by the device
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`subsequent to the occurrence of the reportable event. This may help discourage copying. For
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`example, when a device that is providing an alert of an anomalous event is copied, the “clone,”
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`or copied device will also report the anomalous event.
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`[0016]
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`In one embodiment, authentication methods can be incorporated in a hardware device
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`provided to the user, such as a token or a key fob. (Other possibilities are described below.)
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`Additionally, a device can include a software program for carrying out the method, for example,
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`as software executing on a general—purpose computer, handheld computer, telephone, personal
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`digital assistant, and so on, or in some other manner. The device may, in some implementations,
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`allow the user to input a second secret, such as a PIN, verifier identifier, and so on, in order to
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`generate an authentication code.
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`[0017]
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`In general, in one aspect, the invention relates to an authentication device that
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`generates an identity authentication code by storing an event state in the device, modifying the
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`event state in response to an event, and generating an authentication code that depends, at least in
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`part, on a dynamic value (e.g. a time value), the event state, and a secret associated with the
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`device. The authentication device thus produces a different identity authentication code based on
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`the event state. By comparing a received authentication code to the possible authentication
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`codes that could be generated by the authentication device, the verifier can not only verify the
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`identity of the user, but can also determine the event state, and thereby determine whether one or
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`more events occurred.
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`[0018]
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`In some embodiments, the event state is associated with .one or more reportable
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`events. In some embodiments, the event state is modified in response to a reportable event. In
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`some such embodiments, the event state is stored in the form of event state data, which reflects
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`the state of one or more reportable events. The event state data thus can communicate the event
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`state.
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`[0019]
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`In some embodiments, the method is constructed such that it is not possible for an
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`attacker who has access to the device to determine whether the report of an event was
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`communicated in the authentication code. As briefly described above, the communication of the
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`event information can be referred to as “covert.” On the other hand, if some event information
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`can be deduced by an attacker or observer, then the communication is referred to as “overt.”
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`Covert communication may be beneficial because it can be used to report the occurrence of an
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`event without an attacker becoming aware of the report. Overt communication may be beneficial
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`in that it allows a general observer to become informed about state information. It is possible to
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`signal some part of an event state in a covert manner, and another part in an overt manner.
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`[0020]
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`An implementation of a system for generating an identity authentication code using
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`event state information can include a data store for storing an event state in an authentication
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`device, an event recorder for modifying the event state in response to one or more reportable
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`events, and an authentication code generator for generating an identity authentication code that
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`depends at least in part on a dynamic value, the event state, and a secret associated with the
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`device. Such an implementation can be included as either part of an authentication device (e.g.,
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`a token) or part of a verifier (e.g., a verification computer), or both. For both the device and the
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`verifier, the system can be implemented as software running on a computer, such as a
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`microprocessor or other general purpose computer. The system can also be implemented in
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`hardware, as described above.
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`[0021]
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`In general, in another aspect, the verifier receives authentication information that
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`includes an identity authentication code generated by a device that at least in part depends on
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`time, a secret associated with the device, and an event state. The verifier verifies the identity of
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`the user and determines the event state in response to the received identity authentication code.
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`The verifier can determine whether an event occurred from the event state. The verifier can take
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`action in response to the determined event state, for example, logging the event state for later
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`analysis, warning the system administrator or relevant authorities, or providing more limited
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`access to the location or system than would be granted if a different event state was determined.
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`The authentication information can also include one or more of a user identifier, a PIN,
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`password, a biometric reading, and other additional authentication information.
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`[0022]
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`In some embodiments, the verifier generates an expected identity authentication code
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`that depends at least in part on a dynamic value associated with a time period and the event state.
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`The event state can include an event state secret, described further below, and bits derived from
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`the event state secret, where one or more bits are associated with a time interval.
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`[0023]
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`In general, in another aspect, the invention relates to a system and method for
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`generating an identity authentication code by, for example, an authentication device and/or a
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`verifier. Describing first the device, the device stores a first secret value associated with the
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`authentication device, and a second secret value associated with event state. The device also
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`generates a dynamic value that changes over time. The device derives from the second value and
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`the dynamic value event state data associated with a time period. The device derives a value for
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`a time period from the first value and the event state data. The device then calculates an identity
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`authentication code using the time-specific value as input. The verifier likewise can implement
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`these method steps so as to determine one or more possible authentication codes, depending on
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`the event state data.
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`[0024]
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`In one embodiment, the event state data includes bits each associated with a time
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`period, where the time—specific value is derived from the first value and the respective bit
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`associated with the time period. In such an embodiment, there are two possible states associated
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`with a time period, depending on the value ofthe bit. If an event occurs, the bits are modified in
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`response to the detected event, such that the generated authentication code is the other of the two
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`possible choices. Optionally, the second secret value (associated with the event state) can also
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`be modified in response to the detected event, such that later generations of event state bits will
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`have a different value than normal. The first secret value can be the same as the second secret
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`value, or they can be different values, or they can partially overlap.
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`[0025]
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`In one embodiment, the event state data comprises a number of bits associated with a
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`respective time period, wherein the time-specific value is derived from the first value and the
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`number of bits associated With the respective time period.
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`[0026]
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`In general, in another aspect, a system for generating an identity authentication code
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`associated with an authentication device includes an authentication code generator. The
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`authentication code generator generates an identity authentication code that depends at least in
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`part on a dynamic value that changes over time, an event state indicative of the occurrence of an
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`event, and a secret associated with the authentication device. One embodiment of such a system
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`is implemented as a software program for execution on a processor, such as a microprocessor or
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`general purpose computer. The system can be included in an authentication device or a verifier,
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`or in another system.
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`[0027]
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`The foregoing and other objects, aspects, features, and advantages of the invention
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`will become more apparent from the following description and from the claims.
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`Brief Description of the Drawings
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`[0028]
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`In the drawings, like reference characters generally refer to the same parts throughout
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`the different views. Also, the drawings are not necessarily to scale, emphasis instead generally
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`being placed upon illustrating the principles of the invention.
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`[0029]
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`FIG. 1 is a block diagram depicting an authentication system including an
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`authentication device and a verifier according to an embodiment of the invention.
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`[0030]
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`FIG. 2 is a block diagram depicting the generation of an authentication code
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`according to an embodiment of the invention.
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`[0031]
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`FIG. 3 is a block diagram depicting the generation of an authentication code
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`according to an embodiment of the invention.
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`[0032]
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`FIG. 4 is a block diagram depicting a detailed implementation of the embodiment of
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`FIG. 3.
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`[0033]
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`FIG. 5 is an example demonstrating the use of event state data in generating an
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`authentication code.
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`[0034]
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`FIG. 6 is a flowchart depicting an embodiment of a method for generating an
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`authentication code.
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`[0035]
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`FIG. 7 is a block diagram depicting the generation of an authentication code
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`according to an embodiment of the invention.
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`[0036]
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`FIG. 8 is a block diagram depicting the generation of an authentication code
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`according to an embodiment of the invention.
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`Detailed Description
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`[0037]
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`Referring to FIG. 1, in one embodiment of an authentication system 100 according to
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`the invention, a verifier 105, is used to help securely authenticate the identity of exemplary user
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`110. As used here, “authenticate” means to verify the identity of a user, and so “authenticate”
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`and “verify” can be used interchangeably throughout. Also, although the specification will
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`discuss, for simplicity, authentication of “users,” it should be understood that “users” means any
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`entity requiring authentication such as, for example, a person, animal, device, machine, or
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`computer. The inclusion of a single user 110 is exemplary, and typically a verifier 105 will be
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`used to verify a large number of users 110. Similarly, the inclusion of a single verifier 105 is
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`exemplary, and typically a user 110 can have an authentication attempt verified by one or more
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`of a large number of verifiers 105. In some embodiments, a single verifier 105 is able to verify a
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`user 110, while in other embodiments, two or more verifiers 105 are together required to perform
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`this task.
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`[0038]
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`The verifier 105 can be any sort of device that implements the functions described
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`here. In one embodiment, the verifier 105 is implemented as software running on a server class
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`computer including a processor, memory, and so on, to enable authentication of a large number
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`of users, for example, in an enterprise. The verifier 105 can also be implemented as software
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`running on a desktop computer, laptop computer, special-purpose device, or personal digital
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`assistant (PDA). For example, the verifier 105 can be implemented as a software program
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`running on a general-purpose computer, possibly interacting with one or more other computer
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`programs on the same or a different computer. Some or all of the verifier 105 functionality can
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`be implemented in hardware, for example in an Application Specific Integrated Circuit (ASIC)
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`and the like. In still further embodiments, the verifier 105 can be implemented in a cellular
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`telephone, or specialized hardware embedded in a cellular telephone and adapted to interact with
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`the cellular telephone’s circuitry. Other sizes, shapes, and implementations are possible without
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`departing from the spirit of the invention.
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`[0039]
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`Authentication can result in the performance of one or more actions including,
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`without limitation, providing access or privileges, taking action, or enabling some combination
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`of the two. Access includes, without limitation: access to a physical location, communications
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`network, computer system, and so on; access to such services as financial services and records,
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`health services and records and so on; or access to levels of information or services. The user
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`110 and the verifier 105 can be physically near one another or far apart.
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`[0040]
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`As illustrated, a user 110 can communicate with a user authentication device 120.
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`The user authentication device 120 provides information used to authenticate the user 110. The
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`user authentication device 120 can optionally provide a user interface 130. Communication
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`between the user 110 and the user authentication device 120 can take place via this user interface
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`130. The user interface 130 can provide an input interface, an output interface, or both. An
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`input interface enables the user 110 to communicate information to the user authentication
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`device 120. The input interface can be any mechanism for receiving user input, and can include,
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`without limitation: a keypad or keyboard; one or more push buttons, switches or knobs; a touch
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`sensitive screen; a pointing or pressing device; a trackball; a device for capturing sound, voice or
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`handwriting; a device for capturing biometric input (such as a fingerprint, retina or voice
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`characteristic); and so forth. An output interface enables the user authentication device 120 to
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`communicate information to the user 110 and can be any mechanism for communicating to a
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`user, including, without limitation: a visual display to support alphanumeric characters or
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`graphics such as a LCD display or LED display; an electrophoretic display; one or more light
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`sources; a loudspeaker, a sound or voice generator; a Vibration interface; and so forth. In some
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`embodiments, the user 110 provides, via the user interface 130, identifying information (such as
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`a user identifier, PIN, or password, or a biometric characteristic such as a fingerprint, retina
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`pattern, or voice sample), or possessions (such as physical keys, digital encryption keys, digital
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`certificates, or authentication tokens) to the user authentication device 120.
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`[0041]
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`The user authentication device 120 can take various forms in various embodiments of
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`the invention, provided that the user authentication device 120 performs the functions required of
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`the user authentication device 120 for secure authentication. The user authentication device 120
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`can be implemented in packages having a wide variety of shapes and form factors. For example,
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`the user authentication device 120 can be a credit—card sized and shaped device, or can be much
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`smaller or much larger. One credit—card sized embodiment of the user authentication device 120
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`includes a microprocessor with on-board memory, a power source, and a small LCD display.
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`The embodiment optionally includes a keypad or buttons for PIN entry, entry of authentication
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`information requests, or for other entry or interaction with the device 120. In another
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`embodiment, a credit-card sized device 120 includes a processor with on-board memory that is
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`used as a “smart card,” that can be installed into another device that provides power and/or
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`interface. In still other embodiments, a credit-card sized device 120 is a card such as a credit
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`card including a magnetic strip or other data store on one of its sides. In other embodiments, the
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`user authentication device 120 is a “key fob,” that is, a smaller device with a display and battery
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`that is sized and shaped to fit on a key ring. In yet another embodiment, the user authentication
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`device 120 is a peripheral device that communicates with a computer, telephone, or other device,
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`such as a USB dongle. In still other embodiments, the user authentication device 120 can be a
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`desktop computer, laptop computer, or personal digital assistant (PDA). For example, the
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`authentication device 120 can be implemented as a software program running on a general-
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`purpose computer, possibly interacting with one or more other computer programs on the same
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`or a different computer. In still further embodiments the user authentication device can be a
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`cellular telephone, or specialized hardware embedded in a cellular telephone and adapted to
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`interact With the cellular telephone’s circuitry, such as a SIM card. In this examp