Showing papers on "Password published in 1995"

Network Security: Private Communication in a Public World

Abstract: Acknowledgments. 1. Introduction. Roadmap to the Book. What Type of Book Is This? Terminology. Notation. Primer on Networking. Active vs. Passive Attackc. Layers and Cryptography. Authorization. Tempest. Key Escrow for Law Enforcement. Key Escrow for Careless Users. Viruses, Worms, Trojan Horses. The Multi-level Model of Security. Legal Issues. I. CRYPTOGRAPHY. 2. Introduction to Cryptography. What Is Cryptography? Breaking an Encryption Scheme. Types of Cryptographic Functions. Secret Key Cryptography. Public Key Cryptography. Hash Algorithms. Homework. 3. Secret Key Cryptography. Introduction. Generic Block Encryption. Data Encryption Standard (DES). International Data Encryption Algorithm (IDEA). Advanced Encryption Standard (AES). RC4. Homework. 4. Modes of Operation. Introduction. Encrypting a Large Message. Generating MACs. Multiple Encryption DES. CBC Outside vs. Inside. Homework. 5. Hashes and Message Digests. Introduction. Nifty Things to Do with a Hash. MD2. MD4. MD5. SHA-1. HMAC. Homework. 6. Public Key Algorithms. Introduction. Modular Arithmetic. RSA. Diffie-Hellman. Digital Signature Standard (DSS). How Secure Are RSA and Diffie-Hellman? Elliptic Curve Cryptography (ECC). Zero Knowledge Proof Systems. Homework Problems. 7. Number Theory. Introduction. Modular Arithmetic. Primes. Euclid's Algorithm. Chinese Remainder Theorem. Zn. Euler's Totient Function. Euler's Theorem. Homework Problems. 8. Math with AES and Elliptic Curves. Introduction. Notation. Groups. Fields. Mathematics of Rijndael. Elliptic Curve Cryptography. Homework. II. AUTHENTICATION. 9. Overview of Authentication Systems. Password-Based Authentication. Address-Based Authentication. Cryptographic Authentication Protocols. Who Is Being Authenticated? Passwords as Cryptographic Keys. Eavesdropping and Server Database Reading. Trusted Intermediaries. Session Key Establishment. Delegation. Homework. 10. Authentication of People. Passwords. On-Line Password Guessing. Off-Line Password Guessing. How Big Should a Secret Be? Eavesdropping. Passwords and Careless Users. Initial Password Distribution. Authentication Tokens. Physical Access. Biometrics. Homework. 11. Security Handshake Pitfalls. Login Only. Mutual Authentication. Integrity/Encryption for Data. Mediated Authentication (with KDC). Nonce Types. Picking Random Numbers. Performance Considerations. Authentication Protocol Checklist. Homework. 12. Strong Password Protocols. Introduction. Lamport's Hash. Strong Password Protocols. Strong Password Credentials. Strong Password Credentials Download Protocols. Homework. III. STANDARDS. 13. Kerberos V4. Introduction. Tickets and Ticket-Granting Tickets. Configuration. Logging Into the Network. Replicated KDC's. Realms. Interrealm Authentication. Key Version Numbers. Encryption for Privacy and Integrity. Encryption for Integrity Only. Network Layer Addresses in Tickets. Message Formats. Homework. 14. Kerberos V5. ASN.1. Names. Delegation of Rights. Ticket Lifetimes. Key Versions. Making Master Keys in Different Realms Different. Optimizations. Cryptographic Algorithms. Hierarchy of Realms. Evading Password-Guessing Attacks. Key Inside Authenticator. Double TGT Authentication. PKINIT-Public Keys for Users. KDC Database. Kerberos V5 Messages. Homework. 15. PKI (Public Key Infrastructure). Introduction. Some Terminology. PKI Trust Models. Revocation. Directories and PKI. PKIX and X.509. X.509 and PKIX Certificates. Authorization Futures. Homework. 16. Real-time Communication Security. What Layer? Session Key Establishment. Perfect Forward Secrecy. PFS-Foilage. Denial-of-Service/Clogging Protection. Endpoint Identifier Hiding. Live Partner Reassurance. Arranging for Parallel Computation. Session Resumption. Plausible Deniability. Data Stream Protection. Negotiating Crypto Parameters. Easy Homework. Homework. 17. IPsec: AH and ESP. Overview of Ipsec. IP and Ipv6. AH (Authentication Header). ESP (Encapsulating Security Payload). So, Do We Need AH? Comparison of Encodings. Easy Homework. Homework. 18. IPsec: IKE. Photuris. SKIP. History of IKE. IKE Phases. Phase 1 IKE. Phase - 2 IKE: Setting up Ipsec Sas. ISAKMP/IKE Encoding. Homework. 19. SSL/TLS. Introduction. Using TCP. Quick TCP. Quick History. SSL/TLS Basic Protocol. Session Resumption. Computing the Keys. Client Authentication. PKI as Deployed by SSL. Version Numbers. Negotiating Cipher Suites. Negotiating Compression Method. Attacks Fixed in v3. Exportability. Encoding. Further Reading. Easy Homework. Homework. IV. ELECTRONIC MAIL. 20. Electronic Mail Security. Distribution Lists. Store and Forward. Security Services for Electronic Mail. Establishing Keys. Privacy. Authentication of the Source. Message Integrity. Non-Repudiation. Proof of Submission. Proof of Delivery. Message Flow Confidentiality. Anonymity. Containment. Annoying Text Format Issues. Names and Addresses. Verifying When a Message Was Really Sent. Homework. 21. PEM & S/MIME. Introduction. Structure of a PEM Message. Establishing Keys. Some PEM History. PEM Certificate Hierarchy. Certificate Revocation Lists (CRLs). Reformatting Data to Get Through Mailers. General Structure of a PEM Message. Encryption. Source Authentication and Integrity Protection. Multiple Recipients. Bracketing PEM Messages. Forwarding and Enclosures. Unprotected Information. Message Formats. DES-CBC as MIC Doesn't Work. Differences in S/MIME. S/MIME Certificate Hierarchy. Homework. 22. PGP (Pretty Good Privacy). Introduction. Overview. Key Distribution. Efficient Encoding. Certificate and Key Revocation. Signature Types. Your Private Key. Key Rings. Anomalies. Object Formats. V. LEFTOVERS. 23. Firewalls. Packet Filters. Application Level Gateway. Encrypted Tunnels. Comparisons. Why Firewalls Don't Work. Denial-of-Service Attacks. Should Firewalls Go Away? 24. More Security Systems. NetWare V3. NetWare V4. KryptoKnight. DASS/SPX. Lotus Notes Security. DCE Security. Microsoft Windows Security. Network Denial of Service. Clipper. Homework. 25. Web Issues. Introduction. URLs/URIs. HTTP. HTTP Digest Authentication. Cookies. Other Web Security Problems. Homework. 26. Folklore. Perfect Forward Secrecy. Change Keys Periodically. Multiplexing Flows over a Single SA. Use Different Keys in the Two Directions. Use Different Secret Keys for Encryption vs. Integrity Protection. Use Different Keys for Different Purposes. Use Different Keys for Signing vs. Encryption. Have Both Sides Contribute to the Master Key. Don't Let One Side Determine the Key. Hash in a Constant When Hashing a Password. HMAC Rather than Simple MD. Key Expansion. Randomly Chosen Ivs. Use of Nonces in Protocols. Don't Let Encrypted Data Begin with a Constant. Don't Let Encrypted Data Begin with a Predictable Value. Compress Data Before Encrypting It. Don't Do Encryption Only. Avoiding Weak Keys. Minimal vs. Redundant Designs. Overestimate the Size of Key. Hardware Random Number Generators. Timing Attacks. Put Checksums at the End of Data. Forward Compatibility. Negotiating Parameters. Homework. Bibliography. Glossary. Index.

The S/KEY One-Time Password System

Abstract: This document describes the S/KEY* One-Time Password system as released for public use by Bellcore and as described in reference [3]. A reference implementation and documentation are available by anonymous ftp from ftp.bellcore.com in the directories pub/nmh/...

Pluggable account management interface with unified login and logout and multiple user authentication services

Abstract: A system and method provide transparent access from any system entry service to multiple account management services, and particularly to multiple authentication services on a computer system, supporting unified login and logout. Transparency between system entry services and account management services, including authentication, password, account, and session services, is provided by an application programming interface and a configuration file. The configuration file stores associations between system entry services, and selected account management services, and allows an individual system entry service to be associated with multiple different ones of a given type of account management service, such as authentication services. The application programming interface determines dynamically in response to a request by a system entry service for an account management operation, such as authentication of a user, which account management service is associated with the system entry service by reading the configuration file and queuing pathnames stored therein of the account management services associated with the system entry service currently connecting user to the system. The application programming interface then invokes the queued pathnames for the desired operation. Multiple login is provided by encrypting authentication tokens used by the authentication services associated with a given system entry service with a primary authentication token of one of the authentication services, and subsequently decrypting the encrypted tokens as needed to authenticate the user. With unified login, the user need only provide the primary authentication token. Unified logout is provided by locating and destroying credentials of the user created by the multiple authentication services in response to a request of the valid user to logout.

Job scheduling system for print processing

Abstract: A user equipment issues a job for a plurality of documents to a printing system by one operation. The user equipment assigns attributes to the job, the attributes including the specification of collation/uncollation, the designation of processing start instruction wait, the designation of exclusive processing, and the designation of password input wait. The printing system effects printing of the plurality of documents corresponding to attributes of the documents under control of a job scheduling device. The job scheduling device carries out the pausing of documents included in the job, the modification of attributes, addressing of document receiving failures, and search of a document whose format is to be converted, thereby making it possible to efficiently print the plurality of documents.

Refinement and extension of encrypted key exchange

Abstract: In their recent paper, "Encrypted Key Exchange: Password-based Protocols Secure Against Dictionary Attacks," Bellovin and Merritt propose a novel and elegant method for safeguarding weak passwords. This paper discusses a possible weakness in the proposed protocol, develops some enhancements and simplifications, and provides a security analysis of the resultant minimal EKE protocol. In addition, the basic 2-party EKE model is extended to the 3-party setting; this yields a protocol with some interesting properties. Most importantly, this paper illustrates, once again, the subtlety associated with designing password-based protocols.

Undetectable on-line password guessing attacks

Abstract: Several 3-party-based authentication protocols have been proposed, which are resistant to off-line password guessing attacks. We show that they are not resistant to a new type of attack called "undetectable on-line password guessing attack". The authentication server is not able to notice this kind of attack from the clients' (attacker's) requests, because they don't include enough information about the clients (or attacker). Either freshness or authenticity of these requests is not guaranteed. Thus the authentication server responses and leaks verifiable information for an attacker to verify his guess.

Method and apparatus for cryptographic authentication

Abstract: Method for providing user authentication and a memory for storing a computer program for providing user authentication are described. The method includes the steps of providing a first argument including a one-way cryptographic transformation of a password and a second argument including a one-way cryptographic transformation of a cryptographic combination of the password and a first nonce, computing a first term using the first argument and computing a second term using the first nonce, and comparing the second term with the second argument. The memory storing a computer program, the computer program including, means for providing a first argument including a one-way cryptographic transformation of a password and a second argument including a one-way cryptographic transformation of a cryptographic combination of the password and a first nonce, means for computing a first term using the first argument and computing a second term using the first nonce, and means for comparing the second term with the second argument.

System and method for protecting unauthorized access to data contents

Abstract: A smart card protection system is provided for protecting against unauthorized access of data contents on a smart card through human or electronic-machine tampering. The smart card protection system includes a smart card having an authorized password stored thereon for associated data and a smart card terminal to supply an entered password for accessing the data on the smart card. The smart card includes a comparator to compare the entered password to the stored password, and two counters: a fail counter and a delay counter. The fail counter keeps a fail count indicative of the number of times that the entered password fails to match the stored password. The fail counter is incremented when the entered password fails to match the stored password and decremented when the entered password successfully matches the stored password. The delay counter maintains a delay count that is incremented each time the comparator compares the entered password to the stored password regardless of a match. In the event that the fail count is not equal to its starting value of zero, the smart card denies access to the data contents. Access is denied even though a match might occur after initial misses because the fail count is not zero. Further, when access is denied, a delay period is imposed before comparing the next entered password received from the smart card terminal. The delay period increases each time based upon a function of the delay count.

Visual access to restricted functions represented on a graphical user interface

Abstract: Computer users access and/or execute a selected restricted function on a computer using a graphical user interface (GUI) by entering an iconic password that is defined by selecting two or more visual icons, called code icons, in a sequence called an iconic password sequence. The entered sequence is compared to a target sequence that represents the restricted function. If the entered sequence matches the target sequence, the user is permitted to execute/access the restricted function. The number of possible combinations in the target sequence, and therefore system security, can be increased by inputting both a code icon and a target site for one or more of the components of the target sequence.

Method for securely storing electronic records

Abstract: An improved method of storing or retrieving electronic records. An image identification code and time data provided by a trusted source, as well as a password, are combined to generate a key. The image identification code and time data are stored in a public directory associated with the image data stream. Further, attributes of the image stream, such as its size and a hash of at least a segment of the image data, are determined. The attributes are then used to generated a verification code. The verification code is placed in a private area associated with the data image stream, and the private area is encrypted with the previously generated key.

Apparatus and methods for verifying the identity of a party

Abstract: Apparatus for verifying the identity of a party are disclosed, the apparatus including a database memory that stores a password signal encrypted by operation of a one-way commutative function; a number generator that generates an non-repeating number or signal representative thereof; and a processor element that can generate a challenge signal as a function of the number signal and a selected one-way commutative function and that can further generate a key signal as a function of the encrypted password signal and the number. The system includes a communication port for transmitting the generated challenge signal to a party requesting access to the secure system and for receiving a response from the party; and further includes a comparator element for comparing the received response with the generated key signal and for generating a match signal that indicates whether the response signal received from the party is substantially identical to the encrypted password signal stored in the database memory.

Encryption method and system for portable data

Abstract: A system and method allows portable, encrypted data to be accessible through multiple hosts, including new hosts (14), without requiring a secure link to the new hosts. A split key encryption system encrypts (52) data and stores the encrypted data on a portable device (10). A split of the encryption key is stored (54) in the portable device (10), and another split of the key is stored (54) in a home host (12) . A password-modified key is then made (58) by combining a password with the encryption key. This password-modified key is then reduced (58), with one split being stored on the host (12) and another split stored on the portable device (10) . Data can be accessed with a new host (14) by transferring (78) the host password-modified split to the new host (14) and entering (80) the password into the portable device (10).

Optimal authentification protocols resistant to password guessing attacks

Abstract: Users are typically authenticated by their passwords. Because people are known to choose convenient passwords, which tend to be easy to guess, authentication protocols have been developed that protect user passwords from guessing attacks. These proposed protocols, however, use more messages and rounds than those protocols that are not resistant to guessing attacks. This paper gives new protocols that are resistant to guessing attacks and also optimal in both messages and rounds, thus refuting the previous belief that protection against guessing attacks makes an authentification protocol inherently more expensive.

Yaksha: augmenting Kerberos with public key cryptography

Abstract: The Kerberos authentication system is based on the trusted third-party Needham-Schroeder (1978) authentication protocol. The system is one of the few industry standards for authentication systems and its use is becoming fairly widespread. The system has some limitations, many of which are traceable to the decision of the Kerberos designers to solely use symmetric key cryptosystems. Using asymmetric (public-key) cryptosystems in an authentication protocol would prevent some of the shortcomings. Several such protocols have been proposed and some have been implemented. However, all these designs are either completely different from the Kerberos system, or require major changes to the basic system. Any attempts to improve Kerberos would do so with only minimal impact to the protocol and the source tree. In this work, we describe Yaksha, a new approach to achieving these goals. Yaksha uses as its building block an RSA (Rivest, Shamir & Adelman, 1978) algorithm variant independently invented by Boyd (1989) and by Ganesan and Yacobi (1994), in which the RSA private key is split into two portions. One portion becomes a user's Yaksha password, and the other the Yaksha server's password for that user. Using this simple but useful primitive, we show how we can blend the Kerberos system with a public-key infrastructure to create Yaksha, a more secure version of Kerberos, with minimal changes to the protocol. >

Computer security system

Abstract: An improved computer security system including a portable, electronic Key, an Access Device with Touch Pad, a Lock, a Lock Server and Server Device, and a Master Device. The Access Device provides a means to validate the user to the Key. The Lock is physically located with, and connected to the host computer. Improved security is achieved through the use of "throw-away" passwords, which are generated in a random fashion by the Lock Server, and then loaded directly into volatile memory of Keys, but transferred to a Master Device for loading into volatile memory of Locks. These throw-away passwords are used in a process of cross validation between the Lock and Key, a requirement before access to the host computer is granted. A user specific "touch-print" provides a more secure and more user friendly way of preventing the use of Keys by unauthorized persons. Sensors, e.g., photosensors, within the Key, Lock and Master Device guard against physical attacks. Additional security is obtained by locating the Lock external to the host computer, thereby preventing an unauthorized user from defeating the host computer operating system security.

Propagating plain-text passwords from a main registry to a plurality of foreign registries

Abstract: A network system server that provides password synchronization between a main data store and a plurality of secondary data stores is disclosed. The network server further includes a security server, which is coupled to the main data store, a plurality of clients, coupled to the security server for accessing the main data store wherein each client maintains a unique, modifiable password, and a password synchronization server, coupled to the security server and the plurality of secondary data stores, that provides password propagation synchronization to each of the secondary data stores from a user associated with one of the plurality of clients so that user is able to maintain a single, unique password among plurality of secondary data stores. The password propagation is imposed on the plurality of secondary data stores regardless of the current password status of the secondary data stores.

Configurable password integrity servers for use in a shared resource environment

Abstract: A network system server that provides password composition checking for a plurality of clients is disclosed. The network system server includes a main data store, a security server, which is coupled to the main data store and the plurality of clients, a password synchronization server, which is coupled to the security server, a plurality of password strength servers, each of which is coupled to the password synchronization server, that provides password integrity among the plurality of clients so that each client maintains a password whose composition is consistent with the network server system. Each of the password strength servers is uniquely programmable with respect to performing password composition checking.

Cable tv system using passwords

Abstract: This invention relates to a method of distributing signals to valid subscribers comprised of storing subscriber terminal valid identification codes at a central station, broadcasting promotions of services available to subscribers, each associated with a specific promotion code, selecting one of the services and entering a selected service promotion code into a terminal at a subscriber location, automatically reading an identification number associated with the terminal in response to the entering of a selected promotion code, processing the identification number and the selected promotion code in accordance with an encryption algorithm, and generating an encrypted event request code therefrom, providing the event request code to a verification center, at the verification center, decrypting the event request code, verifying the number against the valid identification codes, and providing a password unique to the terminal and the selected promotion code, entering the password into the terminal at the subscriber location, and providing access to a service utilizing one of the distributed signals corresponding to the selected promotion code to the subscriber in response to the entering of the password.

Securing trusted personal computer system against unauthorized movement

Abstract: A personal computer system is described, having security features enabling control over access to data retained in such a system. The system has a normally closed enclosure, at least one erasable memory element for selective activation to active and inactive states and for receiving and storing a privileged access password when in the active state, an option switch operatively connected with the erasable memory element for setting the erasable memory element to the active and inactive states, a tamper detection switch operatively connected with the erasable memory element for detecting opening of the enclosure, and a system processor operatively connected with the erasable memory element for controlling access to at least certain levels of data stored within the system by distinguishing between entry and non-entry of any stored privileged access password. In addition, switch means are provided for monitoring unauthorized movement of the system together with means for rendering the movement monitoring switch enabled or disabled. When the movement monitoring switch detects movement of the system while the switch is enabled and when the tamper detection switch detects opening of the enclosure, power-up of the system is prevented until the privileged access password (or a power-on password) is successfully entered into the system by a user.

Retrieving plain-text passwords from a main registry by a plurality of foreign registries

Abstract: A network system server that provides password synchronization between a main data store and a plurality of secondary data stores is disclosed. The network system server includes a security server, which is coupled to the main data store, a plurality of clients, which is coupled to the security server for accessing the main data store wherein each client maintains a unique, modifiable password, a password synchronization server, which is coupled to security server and the plurality of secondary data stores, and a password repository, which is coupled to the password synchronization server, that stores the passwords. One of the secondary data stores can retrieve the passwords via the password synchronization server so that each client is able to maintain a single, unique password among the plurality of secondary data stores. Password retrieval is instigated by at least one of the plurality of secondary data stores regardless of the current password status of the secondary data stores.

Method and apparatus for providing upgrades in electricity meters

Abstract: An electricity meter having a protected enabling scheme for activating meter options and upgrades is presented. The meter has a unique serial number, which includes bit-flags indicating which options have already been enabled, stored in the non-volatile RAM. Each option which is not enabled must be requested and a password verified before it can be utilized. At least one password is stored in a read protected location in the non-volatile RAM. The meter is in communication with a computer, e.g., a desktop or laptop type of computer. The password is generated by processing a secret software key and the unique serial number of the meter with an authentication algorithm. The computer is loaded with an upgrade software program, which includes the authentication algorithm. A hardware key which stores a secret software key is attached to a parallel port of the computer. The upgrade software program reads the serial number from the non-volatile RAM in the meter and reads the secret software key from the hardware key, then processes the read secret software key and the read unique serial number of the meter with the stored authentication algorithm to generate at least one password. The password along with an upgrade command are presented to the meter where they are compared to the read-protected password in the meter, and, if there is a match, then the upgrade command initiates codes in the meter to implement one or more stored options or upgrades.

Security system providing lockout for invalid access attempts

Abstract: A security system controlling access to a resource is arranged to operate such that when an attempt to access a resource using a password or PIN fails, the time interval "t" that must elapse before a subsequent attempt at access can be successful, is incremented. By making the increments increasingly large (illustratively, an exponential function of the number "n" of unsuccessful attempts), repeated access attempts by hackers or other unauthorized users is discouraged, because they simply cannot wait the time needed to make a large number of trial and error attempts. On the other hand, valid users, while experiencing a delay prior to access, are nevertheless able to gain access, rather than being completely "lockedout". This approach is a better compromise between access control and denial.

Middleware program with enhanced security

Abstract: The authentication and security mechanism in a first program is used to access an application program which requires a different type of authentication and password. A server program runs in the same machine as the application program. The server program communicates with the first program and it is accessed and it authenticates the user utilizing the security and authentication mechanism of the first program. After the user ID of a user who desires access to the second program has been authenticated using the authentication mechanism of the first program, the server program (a) generates a temporary password for the authenticated user I.D., (b) changes the password for the authenticated user ID to the temporary password, (c) accesses the second program using the authenticated ID and the temporary password, and (d) receives data and/or commands from the first program using the security mechanism from the first program and transmits this data and/or commands to the second program and (e) receives data and/or commands from the second program and transmits the data and/or commands to the user using the security mechanism of the first program.

Removable computer security device

Abstract: An intelligent removable information storage device (100), for coupling to a host microcomputer system (10), includes a local processor unit (106) including apparatus for preventing the microcomputer system from reading from, or writing to, the storage device absent the entry of an appropriate password by a user of the host microcomputer system. The storage device also includes a storage medium (e.g., a magnetic disk) for storing information including at least one password. The local processor unit includes apparatus for preventing access to the information stored in the storage means absent receipt of a valid password.

Paging device including password accessed stored cryptographic keys

Abstract: A paging device includes a cryptographic function and a password accessed cryptographic key look-up table associating each stored key with a password. When an cryptographic message is collected by the paging device, the user can select a relatively long cryptographic key by entering a relatively shorter password. The paging device then applies a cryptographic function to a received message using a selected relatively long cryptographic key, the selection being a function of user entry of a relatively short password. Overall, paging messages in transit, i.e., while broadcast by radio signal, enjoy a high level of security by encryption with a relatively long cryptographic key by a message source. As accessed by the user, however, the cryptographic messages are reviewed in readable form by use of a relatively short password designating a relatively long stored cryptographic key.

Method and apparatus for authenticating the use of software

Abstract: A hardware encoding circuit which generates a code value unique to a particular computer, stores a password unique to an application program and to the particular computer, tests the stored password against a verification value generated by the hardware encoding program each time the application program is run, and generates an error signal if the stored password and the verification value do not match.

Speech analysis method of protecting a vehicle from unauthorized accessing and controlling

Abstract: A speech analysis method of protecting a vehicle from unauthorized accessing and controlling has a mode of voice changing and a mode of changing a protection degree. In the voice changing mode, a system realizing the method is interactively entered in advance a voice password, voice service passwords including a voice changing mode service password, and control commands. The passwords and commands are analyzed in a voice dependent and voice independent modes and stored. Then, the voice changing mode service password is entered into the system the system, is taught the passwords and commands in the voice changing mode and transferred in an operational state. In the mode of changing protection degree, after the passwords and commands, including a voice service password for changing a system protection degree, are interactively entered into the system in advance, the protection degree is changed through interactively entering the protection degree service password the system is taught the password and the commands at the changed protection degree and transferred into the operational state.

Independent one-time passwords

Abstract: Existing one-time password (OTP) schemes suffer several drawbacks. Token-based systems are expensive, while software-based schemes rely on one-time passwords that are dependent on each other. There are disadvantages to authentication schemes that rely on dependent OTP's. It is difficult to replicate the authentication server without lowering security. Also, current authentication schemes based on dependent OTP's only authenticate the initial connection; the remainder of the session is assumed to be authenticated. Experience shows that connections can be hijacked. A new scheme for generating one-time passwords that are independent is presented. The independence property enables easy replication of the authentication server, and authentication that is persistent for the lifetime of a connection. This mechanism is also ideally suited for smart card applications. Our implementation and several applications are discussed.