Efficient Three Party Key Exchange Protocol

Key exchange protocols allow two or more parties communicating over a public network to establish a common secret key called a session key. In 1976, Diffie and Hellman proposed the first practical key exchange (DH key exchange) protocol. In 2005, Abdalla and Pointcheval suggested a new variation of the computational DH assumption called chosen based computational Diffie Hellman (CCDH) and presented simple password based authenticated key exchange protocols. Since then several three party password authenticated key agreement protocols have been proposed In 2007, Lu and Cao proposed a simple 3 party authenticated key exchange (S-3PAKE) protocol. Kim and Koi found that this protocol cannot resist undetectable online password guessing attack and gave fixed STPKE' protocol as a countermeasure using exclusive-or operation. Recently, Tallapally and Padmavathy found that STPKE' is still vulnerable to undetectable online password guessing attack and gave a modified STPKE' protocol. Unfortunately, we find that, although modified STPKE' protocol can resist undetectable online password guessing attack but it is vulnerable to man in the middle attack. Also, we propose and analyze an efficient protocol against all the known attacks

Cryptanalysis of an e_cient three-party password-based key exchange scheme

AbstractIn order to secure communications between two clients with a trusted server's help in public network environments, a three-party password-based authenticated key exchange (3PAKE) scheme is used to provide the transaction confidentiality and e_ciency. In 2010, Lou-Huang proposed a new simple three-party password-based authenticated key exchange (LH-3PAKE) scheme based on elliptic curve cryptography (ECC). By analysis, Lou-Huang claimed that the proposed LH- 3PAKE scheme is not only secure against various attacks, but also more e_cient than previously proposed 3PAKE schemes. However, this paper demonstrates LH-3PAKE scheme is vulnerable to o_-line password guessing attacks by an attacker

Analysis of two pairing-based three-party password authenticated key exchange protocols

Password-Authenticated Key Exchange (PAKE) protocols allow parties to share secret keys in an authentic manner based on an easily memorizable password. Recently, Nam et al. showed that a provably secure three-party password-based authenticated key exchange protocol using Weil pairing by Wen et al. is vulnerable to a man-in-the-middle attack. In doing so, Nam et al. showed the flaws in the proof of Wen et al. and described how to fix the problem so that their attack no longer works. In this paper, we show that both Wen et al. and Nam et al. variants fall to key compromise impersonation by any adversary. Our results underline the fact that although the provable security approach is necessary to designing PAKEs, gaps still exist between what can be proven and what are really secure in practice

Analysis of Two Pairing-Based Three-Party Password Authenticated Key Exchange Protocols

Password-Authenticated Key Exchange (PAKE) protocols allow parties to share secret keys in an authentic manner based on an easily memorizable password. Recently, Nam et al. showed that a provably secure three-party password-based authenticated key exchange protocol using Weil pairing by Wen et al. is vulnerable to a man-in-the-middle attack. In doing so, Nam et al. showed the flaws in the proof of Wen et al. and described how to fix the problem so that their attack no longer works. In this paper, we show that both Wen et al. and Nam et al. variants fall to key compromise impersonation by any adversary. Our results underline the fact that although the provable security approach is necessary to designing PAKEs, gaps still exist between what can be proven and what are really secure in practice

Contributions to Securing Software Updates in IoT

The Internet of Things (IoT) is a large network of connected devices. In IoT, devices can communicate with each other or back-end systems to transfer data or perform assigned tasks. Communication protocols used in IoT depend on target applications but usually require low bandwidth. On the other hand, IoT devices are constrained, having limited resources, including memory, power, and computational resources. Considering these limitations in IoT environments, it is difficult to implement best security practices. Consequently, network attacks can threaten devices or the data they transfer. Thus it is crucial to react quickly to emerging vulnerabilities. These vulnerabilities should be mitigated by firmware updates or other necessary updates securely. Since IoT devices usually connect to the network wirelessly, such updates can be performed Over-The-Air (OTA). This dissertation presents contributions to enable secure OTA software updates in IoT. In order to perform secure updates, vulnerabilities must first be identified and assessed. In this dissertation, first, we present our contribution to designing a maturity model for vulnerability handling. Next, we analyze and compare common communication protocols and security practices regarding energy consumption. Finally, we describe our designed lightweight protocol for OTA updates targeting constrained IoT devices. IoT devices and back-end systems often use incompatible protocols that are unable to interoperate securely. This dissertation also includes our contribution to designing a secure protocol translator for IoT. This translation is performed inside a Trusted Execution Environment (TEE) with TLS interception. This dissertation also contains our contribution to key management and key distribution in IoT networks. In performing secure software updates, the IoT devices can be grouped since the updates target a large number of devices. Thus, prior to deploying updates, a group key needs to be established among group members. In this dissertation, we present our designed secure group key establishment scheme. Symmetric key cryptography can help to save IoT device resources at the cost of increased key management complexity. This trade-off can be improved by integrating IoT networks with cloud computing and Software Defined Networking (SDN).In this dissertation, we use SDN in cloud networks to provision symmetric keys efficiently and securely. These pieces together help software developers and maintainers identify vulnerabilities, provision secret keys, and perform lightweight secure OTA updates. Furthermore, they help devices and systems with incompatible protocols to be able to interoperate