the present study-both qualitative and quantitative--explored fifty efl learners’ preferences for receiving error feedback on different grammatical units as well as their beliefs about teacher feedback strategies. the study also examined the effect of the students’ level of writing ability on their views about the importance of teacher feedback on different error types. data was gathered throug...

increasing the popularity of sip based services (voip, iptv, ims infrastructure) lead to concerns about its ‎security. the main signaling protocol of next generation networks and voip systems is session initiation protocol ‎‎(sip). inherent vulnerabilities of sip, misconfiguration of its related components and also its implementation ‎deficiencies cause some security concerns in sip based infra...

We reveal instances of unsoundness, incompleteness, and redundancy in the cryptographic protocol analysis logic of Gong, Needham and Yahalom. Solutions are proposed for each of these problems. The logic is extended to formalize the use of an uncertiied key in the Yahalom protocol, and our analysis of the protocol suggests the possibility of a redundancy in the protocol.

We present a reduction semantics for the LYSA calculus extended with session information, for modelling cryptographic protocols, and a static analysis for it. If a protocol passes the analysis then it is free of replay attacks and thus preserves freshness. The analysis has been implemented and applied to a number of protocols, including both original and corrected version of Needham-Schroeder p...