Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
  • G06F21/30—Authentication, i.e. establishing the identity or authorisation of security principals
  • G06F21/45—Structures or tools for the administration of authentication
  • G06F21/46—Structures or tools for the administration of authentication by designing passwords or checking the strength of passwords
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
  • G06F3/023—Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
  • G06F3/0233—Character input methods
  • G06F3/0236—Character input methods using selection techniques to select from displayed items
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/048—Interaction techniques based on graphical user interfaces [GUI]
  • G06F3/0487—Interaction techniques based on graphical user interfaces [GUI] using specific features provided by the input device, e.g. functions controlled by the rotation of a mouse with dual sensing arrangements, or of the nature of the input device, e.g. tap gestures based on pressure sensed by a digitiser
  • G06F3/0489—Interaction techniques based on graphical user interfaces [GUI] using specific features provided by the input device, e.g. functions controlled by the rotation of a mouse with dual sensing arrangements, or of the nature of the input device, e.g. tap gestures based on pressure sensed by a digitiser using dedicated keyboard keys or combinations thereof
  • G06F3/04895—Guidance during keyboard input operation, e.g. prompting

Definitions

• the present invention relates generally to computer systems and in particular to the treatment of passwords at log-on in such systems.
• a password is constituted of a succession of symbols taken within a predefined alphabet (for example: 4 numerical values for PIN code).
• a chosen password complies with a predefined policy.
• US 2004/250139 and US 2009/158406 present solutions for selecting such passwords.
• the invention is directed to a method of verification of an input password during log-on of a user to an entity protected by a password.
• a processor receives at least one character of the input password; and verifies that the at least one received character complies with a predefined property that sets at least one requirement for allowable passwords.
• the processor further verifies that the completed input password corresponds to the password that protects the entity.
• the completed input password comprises a first part and a second part, the property being expressed by the second part and compliance with the property is verified by processing the first part to see if the processed first part matches the second part.
• the property is dependent on the user.
• the processor determines that a brute force attack has been attempted upon detection of a predetermined number of input passwords or parts of input passwords that do not respect the property for the user. It is advantageous to take appropriate action upon determination that a brute force attack has been attempted. Such appropriate action comprises at least one of issuing a warning to an administrator, issuing a warning to the user, blocking the system and waiting a predetermined time before accepting further log-on attempts.
• the invention is directed to a device for verifying an input password during log-on of a user to an entity protected by a password.
• the device comprises an interface for receiving password characters; and a processor for verifying that at least one received password character complies with a predefined property that sets at least one requirement for allowable passwords.
• the interface is further for receiving an indication that the input password is complete and wherein the processor is further for verifying that the completed input password corresponds to the password that protects the entity.
• the completed input password comprises a first part and a second part, wherein the property is expressed by the second part, and the processor is adapted to verify compliance with the property by processing the first part to see if the processed first part matches the second part.
• the property is dependent on a user of the password .
• the processor is further for determining that a brute force attack has been attempted upon detection of a predetermined number of input passwords or parts of input passwords that do not respect the property for the user. It is advantageous to take appropriate action upon determination that a brute force attack has been attempted. Such appropriate action comprises at least one of issuing a warning to an administrator, issuing a warning to the user, blocking the system and waiting a predetermined time before accepting further log-on attempts.
• the invention is directed to a computer program product storing instructions of a software program that, when executed by a processor during log-on of a user to an entity protected by a password, receives at least one character of an input password; and verifies that the at least one received character complies with a predefined property that sets at least one requirement for allowable passwords.
• Figure 2 illustrates a method of password generation according to a preferred embodiment of the present invention.
• Figure 3 illustrates a method of password verification according to a preferred embodiment of the present invention.
• FIG. 1 illustrates an exemplary system in which the invention may be implemented.
• the system comprises a computing device (“computer") 1 10 and an authentication server 120; it will be appreciated that the invention may be implemented on the computer 1 10, the authentication server 120, or both the computer 1 10 and the authentication server 1 20.
• the computer 1 10 and the authentication server 120 can be any kind of suitable computer or device capable of performing calculations, such as a standard Personal Computer (PC) or workstation.
• the computer 1 10 and the authentication server 120 each preferably comprise at least one processor 1 1 1 , 121 , RAM memory 1 12, 122, a user interface 1 13, 123 for interacting with a user, and a second interface 1 14, 124 for interaction with other devices over connection 130.
• the computer 1 10 and the authentication device 120 each also preferably comprise an interface for reading a software program from a digital data support 140 that stores instructions that, when executed by a processor, performs any of the password methods described hereinafter.
• a software program from a digital data support 140 that stores instructions that, when executed by a processor, performs any of the password methods described hereinafter.
• the skilled person will appreciate that the illustrated devices are very simplified for reasons of clarity and that real devices in addition would comprise features such as persistent storage devices.
• a main idea is to add a property a (also called 'rule' or 'function') to the set of passwords ⁇ . This will split the complete password space into two distinct subsets:
• the rules that define them may for ease of implementation overlap, in which case one rule should take precedence over the other.
• a rule that forbids the use of the year of birth of a user advantageously overrules any rules that would otherwise allow that specific combination.
• the choice of the property a is a trade-off between password entropy (size of ⁇ ⁇ ) and detectability of an attack (size of ⁇ ,).
• the use of the property a allows detection of brute force attacks. If an attacker systematically tries all password values, this will necessarily include the elements of ⁇ ,. In addition, dictionary attacks may be countered by adding known or likely dictionary elements to ⁇ ,.
• the property a can be a complex function. It can apply to the complete password but should preferably be ensured for each symbol entry by the user interface. In this case, the symbols that can be entered at a given step depend on previously entered symbols.
• the property a partitions the password space in two sections that are "well mixed" and of a non-negligible size, in order to ensure that a random password guessing has a non-negligible probability of using a password from the invalid subset.
• the property a could be to alternate between uppercase and lowercase letters.
• any character (uppercase or lowercase) can be chosen during password creation.
• the user interface proposes the set of lowercase characters if the previous one was uppercase and vice versa. The property a is therefore verified at each step of the creation of the password.
• the property a may depend on various elements, like for example the user name.
• two users can have different rules to construct their passwords. For example, if the number of characters of the username is odd (respectively even), then the password should contain only uppercase (respectively lowercase) characters. Any request composed of mixed uppercase and lowercase characters will be considered as an attack. Another example is to require the sum of the number of characters of the user name and the password to be even (or odd).
• a too complex property can have the following drawbacks: resulting passwords may be difficult to remember, and the size of valid password set ⁇ ⁇ may become too small to ensure sufficient entropy.
• the overall level of security of the system depends on the secrecy of the property a. Knowing or guessing this property would allow to build the set of the valid password values ( ⁇ ⁇ ) and perform a dictionary attack with this set, without being detected. To make it more difficult for an attacker to reconstruct the valid subset ⁇ ⁇ , it is advantageous not to actively highlight constraints in the user interface at the login moment, but to do so only during password construction. Furthermore, the classical countermeasures used in authentication systems (e.g. maximum number of tries and imposed delay between incorrect password entries) can still be used in combination with the solution of the present invention.
• the example also highlights the generalization of traditional countermeasures, for example avoiding dictionary attacks.
• a first step can be to exclude a particular set, "the dictionary", of combinations that are used too often or that are too simple, for example the same digit repeated 4 times (e.g. "7777") or where the 4 digits are in an increasing sequence (e.g. "1234").
• the system thus implemented will verify during password generation that the chosen PIN code is not part of the dictionary and, if this is the case, validates the chosen PIN code.
• login or other kinds of authentication
• a PIN code from the invalid subset ⁇ is entered, the system raises an exception and takes the planned countermeasures.
• the second step can be to integrate a function a to partition the password space ⁇ into a valid subset and an invalid subset (of which the latter will be combined with the "dictionary").
• the function a may state that the parity of every digit has to change with respect to the previous one.
• the system optionally, enforces the observation of this rule during the generation phase by modifying its interface and, optionally, showing only valid digits.
• password authentication the system checks that the entered PIN respects the rule a; if it doesn't, then an exception is raised and the system takes the planned countermeasures.
• the function a allows some combinations that are forbidden by the dictionary condition.
• the third step is to enforce, at password generation, the active condition via the interface or simply refusing an invalid PIN code.
• the system proceeds as in step two and three verifying both conditions and otherwise raising an exception.
• Figure 2 illustrates a method for password generation according to a preferred embodiment of the present invention. The method may be implemented on the computer 1 10 or on the authentication server 120 interacting with the computer 1 10.
• the system may propose possible characters, i.e. characters that comply with the property a, for the next user input, step 210.
• this step may be skipped, provided that the choice is free.
• the step may be substituted by a step that verifies that the input character complies with the property a and refuses to accept the character if this is not the case.
• step 220 a character is received from the user, step 220, and it is verified if the password is complete, step 230. This may be indicated by user input (such as if the user clicks on an icon or presses 'Return'), but it may also be implicit. If the password is complete, then the method ends in step 240; if not, the method returns to step 210.
• Figure 3 illustrates a method of password verification according to a preferred embodiment of the present invention.
• the password verification method is advantageously performed when a user logs on to an entity (an account, a device, a server etc.) protected by the password to be verified.
• the verification method may be implemented by the computer 1 10 or the authentication server 120.
• a character is received, step 310, and it is verified, step 320, if the character complies with the property a. If this is not the case, then it may be determined that a brute force attack has been attempted and appropriate action may be taken in step 330.
• Appropriate action may for example be issuing a warning to an administrator and/or the user, blocking the system after the input of X non-compliant passwords, and the use of a delay before accepting a further attempt. It will be appreciated that it is possible to keep the appropriate action on hold until the entire password has been input, in which case the method continues with step 340. Appropriate action may also be deferred until a certain number of incorrect passwords (i.e. passwords that do not respect the property a) have been entered; the number of incorrect passwords may consider the time, e.g. X number of incorrect passwords in the last Y seconds.
• a certain number of incorrect passwords i.e. passwords that do not respect the property a
• step 340 it is verified if the password is complete, which is done in a manner similar to step 230 of the generation method. If this is not the case, then the method waits for the reception of the next character in step 210; however, if this is the case, then the input password is verified, step 350, although this may not be necessary if the property a is not respected, as such a password cannot be correct. In other words, it is verified that the input password corresponds to the password that protects the entity. As mentioned, the appropriate action may be taken at this point, as well as earlier. It should also be noted that compliancy with the property a may be postponed until this step (i.e. step 320 does not occur until step 350, either before verification of the password or after unsuccessful verification of the password).
• Alternative embodiment compliancy with the property a may be postponed until this step (i.e. step 320 does not occur until step 350, either before verification of the password or after unsuccessful verification of the password).
• a different way to express the property a is to attach at the end of the password, integrally chosen by the user, one or more characters chosen by the server as "authenticating padding". It is preferable that the characters are the result of a pseudo-random function taking as parameters the password entered by the user, his login and a server side secret parameter.
• the drawback of this solution is that the user is obliged to learn few more characters added to his password.
• HMAC Hash-based Message Authentication Code
• the system computes an HMAC of it and returns the "complete" password composed by chaining the password entered by the user and the first n bits of the HMAC.
• the user enters the password, whereupon the system checks if it is a possible password, verifying that the last n bits correspond with the HMAC value. It will be appreciated that the present invention can provide a way of verifying passwords that:

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• 2010
  • 2010-05-11 EP EP10305498A patent/EP2386973A1/en not_active Withdrawn
• 2011
  • 2011-05-06 WO PCT/EP2011/057345 patent/WO2011141388A1/en not_active Ceased
  • 2011-05-06 JP JP2013509523A patent/JP5833640B2/ja not_active Expired - Fee Related
  • 2011-05-06 EP EP11718990.2A patent/EP2569725B1/en not_active Not-in-force
  • 2011-05-06 KR KR1020127029352A patent/KR20130072210A/ko not_active Ceased
  • 2011-05-06 US US13/697,135 patent/US9384343B2/en not_active Expired - Fee Related

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