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We investigate the security of Diffie-Hellman key exchange as used in popular Internet protocols and find it to be less secure than widely believed. First, we present Logjam, a novel flaw in TLS that lets a man-in-the-middle downgrade connections to "export-grade" Diffie-Hellman. To carry out this attack, we implement the number field sieve discrete logarithm algorithm. After a week-long precomputation for a specified 512-bit group, we can compute arbitrary discrete logarithms in that group in about a minute. We find that 82% of vulnerable servers use a single 512-bit group, and that 8.4% of Alexa Top Million HTTPS sites are vulnerable to the attack. In response, major browsers have changed to reject short groups. We go on to consider Diffie-Hellman with 768- and 1024-bit groups. We estimate that even in the 1024-bit case, the computations are plausible given nation-state resources. A small number of fixed or standardized groups are used by millions of servers; performing precomputation for a single 1024-bit group would allow passive eavesdropping on 18% of popular HTTPS sites, and a second group would allow decryption of traffic to 66% of IPsec VPNs and 26% of SSH servers. A close reading of published NSA leaks shows that the agency's attacks on VPNs are consistent with having achieved such a break. We conclude that moving to stronger key exchange methods should be a priority for the Internet community. [ABSTRACT FROM AUTHOR]

Current network use is dominated by content distribution and retrieval yet current networking protocols are designed for conversations between hosts. Accessing content and services requires mapping from the what that users care about to the network's where. We present Content-Centric Networking (CCN) which uses content chunks as a primitive---decoupling location from identity, security and access, and retrieving chunks of content by name. Using new approaches to routing named content, derived from IP, CCN simultaneously achieves scalability, security, and performance. We describe our implementation of the architecture's basic features and demonstrate its performance and resilience with secure file downloads and VoIP calls. [ABSTRACT FROM AUTHOR]

Many Web sites embed third-party content in frames, relying on the browser's security policy to protect against malicious content. However, frames provide insufficient isolation in browsers that let framed content navigate other frames. We evaluate existing frame navigation policies and advocate a stricter policy, which we deploy in the open-source browsers. In addition to preventing undesirable interactions, the browser's strict isolation policy also affects communication between cooperating frames. We therefore analyze two techniques for interframe communication between isolated frames. The first method, fragment identifier messaging, initially provides confidentiality without authentication, which we repair using concepts from a well-known network protocol. The second method, post-Message, initially provides authentication, but we discover an attack that breaches confidentiality. We propose improvements in the post Message API to provide confidentiality; our proposal has been standardized and adopted in browser implementations. [ABSTRACT FROM AUTHOR]

It is informed that since its inception, the Internet has thrived on a myriad of innovative concepts and technologies. Recently, the peer-to-peer (P2P) architecture has evolved to empower masses of users to share a variety of file types, usually within a narrow niche such as music. There are many different applications of P2P, including file sharing, distributed computing, and real-time communication. In the P2P configuration, a computer becomes a node in a file-sharing network for users with common P2P applications. Using this scheme, a computer becomes a "peer" with simultaneous client and server roles. P2P protocols reduce the barriers to assigning a public network address to a peer, thus effectively creating a server within a client's name space. Each P2P network is defined by its client-side software, which uses its own unique set of protocols. P2P applications are designed to bypass the traditional Domain Name System (DNS) by retrofitting peers into the DNS model. As information technology departments are rewarded for their ability to preserve stability, P2P disrupts the traditional networking model and risks causing networking instability. With networks without servers being administered by unskilled users, many organizations are trying to keep this technology under control.

This article investigates the security problems in the 802.11-based data link protocol, Wireless Equivalent Privacy (WEP). It is evident that anyone with a radio receiver can eavesdrop on a wireless local area network (WLAN), and therefore widely acknowledged that a WLAN needs a mechanism to counter this threat. The IEEE 802.11 standard defines a data confidentiality mechanism known as WEP. The security goal of WEP is data confidentiality equivalent to that of a wired LAN. WEP falls short of this objective, which is an intuitively appealing but vague security goal. As a consequence, WEP was insufficiently thought through, and numerous flaws quickly appeared. The discovery of shortcomings led to a process to replace WEP by more robust security protocols. The study of WEP flaws illustrates the difficulties in security protocol design. An understanding of these flaws helps clarify the choices made by the designers of the new protocols. WEP has several serious inherent problems. It does not meet its fundamental goals of wired-equivalent confidentiality.

This article discusses firewall technology and the security protocols that have been proposed for the Internet, transport and application layer. A firewall builds a blockade between an internal network that is assumed to be secure and trusted, and another network, usually an external (inter)network, such as the Internet, that is not assumed to be secure and trusted. The general reasoning behind firewall usage is that without a firewall, a network's systems are more exposed to inherently insecure Internet protocols and corresponding services, such as probes and attacks from hosts elsewhere on the Internet. A firewall system usually consists of screening routers and proxy servers. A screening router is a multiported IP router that applies a set of rules to each incoming IP packet and decides whether it is to be forwarded on or not. A proxy server is a server process running on a firewall system to perform a specific TCP/IP function as a proxy on behalf of the network users. Firewall advocates consider firewalls as important additional safeguards because they aggregate security functions in a single point, simplifying installation, configuration and management.

The Internet can bring down physical barriers to commerce, almost immediately giving even the smallest business access to untapped markets around the world. By the same token, consumers can conduct business and make purchases from organizations previously unavailable to them. Armed with these goals, individuals have flocked to the Internet, and most businesses have set out to set up storefronts on the Internet and its World Wide Web. Just about every major business in the U.S., perhaps in the world, has a home page on the Internet on which can be found information about their services and products. As the Internet grew, the community expanded, and the existing security framework was found lacking. Over the past few years, people have seen evidence of this fact, in the form of Internet-based attacks on commercial systems. Awareness of these attacks has spawned the use of network security tools, such as firewalls, to protect individual networks from attack. More sophisticated attacks can take advantage of basic flaws in the Internet's infrastructure. INSET: Basic Flaws in Internet Infrastructure..

The article focuses on authorization management for digital library. University information services need unobtrusive but effective means of providing different members different levels of service. Safe Dealing (SD) is an authorization mechanism motivated by information delivery that has many other potential applications among popular services. SD's extreme target is the circumstance in which some user requests a valuable Internet service of a server. This server should grant the request only if the requester is appropriately authorized. Furthermore, the requester will want to avoid sharing personal information beyond what is reasonable for the transaction at hand. In fact, SD can deny digital servers any information about any user except the Internet Protocol address to which they should deliver results and can still reliably limit delivery as specified by service proprietors' policies. SD must enable somebody to trace any suspect transaction back to its human originator. SD limits this to transaction clearance centers made trustworthy by business controls and audits not practically or economically exercised in large numbers of individual servers.