Abstract: Three-party EKE was proposed to establish a session key between two clients through a server However, three-party EKE is insecure against undetectable on-line and off-line password guessing attacks In this paper, we first propose an enhanced three-party EKE to withstand the security risk in three-party EKE We also propose a verifier-based three-party EKE that is more secure than a plaintext-equivalent mechanism in which a compromise of the server's database will not result in success in directly impersonating clients

Abstract: A device that performs private key operations (signatures or decryptions), and whose private key operations are protected by a password, can be immunized against offline dictionary attacks in case of capture by forcing the device to confirm a password guess with a designated remote server in order to perform a private key operation. Recent proposals for achieving this allow untrusted servers and require no server initialization per device. In this paper we extend these proposals to enable dynamic delegation from one server to another; i.e., the device can subsequently use the second server to secure its private key operations. One application is to allow a user who is traveling to a foreign country to temporarily delegate to a server local to that country the ability to confirm password guesses and aid the user's device in performing private key operations, or in the limit, to temporarily delegate this ability to a token in the user's possession. Another application is proactive security for the device's private key, i.e., proactive updates to the device and servers to eliminate any threat of offline password guessing attacks due to previously compromised servers.

Abstract: In 2000, Sun proposed an efficient remote user authentication scheme using smart cards (published in IEEE Transactions on Consumer Electronics, vol. 46, no. 4, 2000) Recently, Chien et al. pointed out that Sun's scheme only achieve the unilateral authentication. That is, only the authentication server can authenticate that of the remote user while the use cannot authenticate that of the server. Chien et al. further proposed a new efficient and practical solution to achieve the mutual user authentication (published in Computer & Security, vol. 21, No. 4 2002). This paper, however, will demonstrate that Sun's scheme is vulnerable to the off-line and on-line password guessing attacks and Chien et al.'s scheme is vulnerable to the parallel session attack.

Abstract: A password strength checking method has the steps of inputting a password to be checked, generating a plaintext password candidate according to the same generation procedure as that used by a password guessing tool, determining whether or not the inputted password and the generated password candidate match each other, directing generation of the next password candidate when the match is not determined, determining strength of the inputted password based on the number of the generated password candidates when the match is determined, and outputting information of the determined password strength.

Abstract: A password is held as part of authentication credentials on a secure media such as a smart card of a secure file. A user presents a PIN number which is different from the card which causes GINA or scripting module to unlock the secure module and extract the password. The password is presented to the operating system or an application to authenticate the user. The password may change without the user being aware of the new password. The GINA or scripting module recognises a change password request or screen and generates a new random password which is passed to the operating system or application and, if authenticated, stored as part of the authentication credentials.

Abstract: In an internet environment, such as UNIX, a remote user has to obtain the access right from a server before doing any job. The procedure of obtaining acess right is called a user authentication protocol. User authentication via user memorable password provides convenience without needing any auxiliary devices, such as smart card. A user authentication protocol via username and password should basically withstand the off-line password guessing attack, the stolen verifier attack, and the DoS attack. Recently, Peyravian and Zunic proposed one password transmission protocol and one password change protocol. Later, Tseng et al. (2001) pointed out that Peyravian and Zunic's protocols can not withstand the off-line password guessing attack, and therefore proposed an improved protocol to defeat the attack. Independently, Hwang and Yeh also showed that Peyravian and Zunic's protocols suffer from some secury flaws, and an improved protocol was also presented. In this paper, we show that both Peyravian and Zunic's protocols and Tseng et al.'s improved protocol are insecure against the stolen verifier attack. Moreover, we show that all Peyravian and Zunic's, Tseng et al.'s, and Hwang and Yeh's protocols are insecure against DoS attack.

Abstract: Recently, Tseng et al. proposed an improvement on Peyravian and Zunic's protected password transmission scheme and protected changing scheme to remove some security flaws. However, as we will point out in this paper, any adversary can intercept the request for changing the password sent by a legal user and modify it with a wrong password. Furthermore, we shall also propose an improved version of their protected password changing scheme to help it out of the trouble.

Abstract: This paper proposes a common password method for users who need to protect multiple accounts using passwords. It requires a user to remember only one password, called a common password, to access any of his/her accounts. Each account is protected by a different password, called a specific password. It is generated by a one-way hash function of an account-specific random number that is stored at the account server or a proxy in an encryption form, where the encryption key is derived from the common password. Compared with a convenient but insecure practice of using one or several passwords to protect multiple accounts, the common password method is convenient and secure. It assures that compromising one specific password does not reveal the common password and any other specific password. A Web-based implementation for the common password method is also presented in this paper. It employs a Web server to store every user's account identifiers and encrypted random numbers, and to supply them to the user in a Web page that contains a password calculator written in JavaScript. The user can compute a specific password using a Web browser on his/her computer for any application that requires password authentication.

Abstract: A password-based protocol for authenticated key exchange must provide security against attacks using low entropy of a memorable password. We propose a new password-based protocol for authenticated key exchange, EPA (Efficient Password-based protocol for Authenticated key exchange), which has smaller computational and communicational workloads than previously proposed protocols with the same security requirements. EPA is an asymmetric model in which each client has a password and the server has a password file. While the server's password file is compromised, the client's password is not directly exposed. However, if the adversary mounts an additional dictionary attack, he can obtain the client's password. By using a modified amplified password file, we construct EPA+, which is secure against dictionary attack and server impersonation even if the server's password file is compromised.

Abstract: One-time passwords (OTPs) have the advantage over regular passwords in that they protect legitimate users from replay attacks by generating a different password for each time of authentication. There are two variables that play a major role in creating a secure OTP; they are the passphrase length and the number of times the one-time password should be hashed. It is already a known fact that the larger the passphrase length the better is the security an OTP can offer. However, there is still a lack of quantitative analysis carried out to study how optimal Web security can be achieved. We propose a novel Web security evaluation model that can be used to measure the strength of a one-time password.

Abstract: SUMMARY Recently, Zhu et al. proposed an passwordbased authenticated key exchange protocol based on RSA such that it is efficient enough to be implemented on most of the target low-power devices such as smart cards and low-power Personal Digital Assistants in wireless networks. They claimed that the proposed scheme is secure against dictionary attacks. In this paper, we show that the scheme proposed by Zhu et al. is insecure against undetectable on-line password guessing attacks. Furthermore, we examine Zhu et al.’s protocol and find that Zhu et al.’s protocol does not achieve explicit key authentication. An improved version is then proposed to defeat the undetectable on-line password guessing attacks and also provide explicit key authentication.

Abstract: From the Publisher: Covers electronic and wireless eavesdropping, computer surveillance, intelligence gathering, password cracking, keylogging, data duplication, black bag computer spy jobs, reconnaissance, risk assessment, legal issues, and advanced spying techniques used by the government Author shares easily-implemented countermeasures against spying to detect and defeat eavesdroppers and other hostile individuals Addresses legal issues, including the U.S. Patriot Act, legal spying in the workplace, and computer fraud crimes Companion Web site contains links to security tools and useful security information resources

Abstract: : A message in a protocol is said to have a type-flaw if it was created with an intended type, but is later received and treated as a different type. A type-flaw guessing attack is an attack in which a type-flaw is induced in a protocol to enable a password guessing attack to occur. Heather, Lowe, and Schneider in "How to Prevent Type Flaw Attacks on Security Protocols" (July 2000) prove that attacks that use type-flaws can be prevented if honest agents tag messages with their intended types. However, their tagging scheme cannot be used in a password protocol since it allows a guess to be directly verified using the tags inside password encryptions. In this paper, the authors prove that following a modification of Heather et al.'s scheme, most type-flaw guessing attacks can still be prevented.

Abstract: Some common onetime password authentication protocols are analyzed.A practical efficient onetime password authentication protocol is presented which based on the symmetric algorithm,which conquers common challengeresponse protocol weakness and can achieve mutual authentication and avoid replay attack and personating attack.It also can boost up the security of the application security system by integrating with it.

Abstract: We present a new password system, called dual password system, with the user verification procedure. Dual password system is the first password system in the world preventing the exposure of secret information to imposter at the terminal. User of dual password system matches two alphabets at same location of first password and second password iteratively for inputting password. Therefore, the deriving method of first password and second password from the password is important in dual password system. Related to the deriving method of first password and second password from password, a new problem, called dual password derivation problem, is defined, and the evaluation factors for the solutions of the dual password derivation problem are presented.

Abstract: In 1999, Seo and Sweeney proposed a simple authenticated key agreement protocol(SAKA) that was designed to act as a Diffie-Hellman scheme with user authentication However, the protocol was subsequently found to have security flaws and enhanced in the literature Recently, Ku and Wang showed a variant of SAKA This paper shows that the Ku and Wang’s scheme is still vulnerable to an off-line password guessing attack The attack illustrates that extreme care must be taken when passwords are combined to provide user authentication in the key agreement protocols This paper also presents a new key agreement protocol that resists the guessing attacks mounted by either passive or active network attackers, allowing low-entropy passwords to be used safely The protocol has more efficient performance by reducing the number of protocol steps

Abstract: Recently, Yeh and Sun proposed a simple authenticated key agreement protocol resistant to password guessing attacks called SAKA that is simple and cost-effective. And they provided a formal proof o...

Abstract: From Seo and Sweeney proposed SAKA (Simple Authenticated Key agreement Algorithm), many SAKA variants were proposed to cope with the weaknesses in SAKA. However, they still are vulnerable to off-line password guessing attack. This paper proposes a new secure authenticated key exchange protocol that can resist off-line password guessing attack. To solve the vulnerability of former protocols, keyed one-way hash function is used in the process of key verification. Proposed protocol solves all weaknesses in SAKA and its variants.