Time-based One-time Password Algorithm

Time-based One-time Password Algorithm (TOTP) is an algorithm that computes a one-time password from a shared secret key and the current time. It has been adopted as Internet Engineering Task Force standard RFC 6238, is the cornerstone of Initiative For Open Authentication (OATH), and is used in a number of two-factor authentication systems.

TOTP is an example of a hash-based message authentication code (HMAC). It combines a secret key with the current timestamp using a cryptographic hash function to generate a one-time password. The timestamp typically increases in 30-second intervals, so passwords generated close together in time from the same secret key will be equal.

In a typical two-factor authentication application, user authentication proceeds as follows: a user enters username and password into a website or other server, generates a one-time password for the server using TOTP running locally on a smartphone or other device, and types that password into the server as well. The server then also runs TOTP to verify the entered one-time password. For this to work, the clocks of the user's device and the server need to be roughly synchronized (the server will typically accept one-time passwords generated from timestamps that differ by ±1 time interval from the client's timestamp). A single secret key, to be used for all subsequent authentication sessions, must have been shared between the server and the user's device over a secure channel ahead of time. If some more steps are carried out, the user can also authenticate the server using TOTP.

ISO 8601

ISO 8601 Data elements and interchange formats – Information interchange – Representation of dates and times is an international standard covering the exchange of date and time-related data. It was issued by the International Organization for Standardization (ISO) and was first published in 1988. The purpose of this standard is to provide an unambiguous and well-defined method of representing dates and times, so as to avoid misinterpretation of numeric representations of dates and times, particularly when data are transferred between countries with different conventions for writing numeric dates and times.

In general, ISO 8601 applies to representations and formats of dates in the Gregorian (and potentially proleptic Gregorian) calendar, times based on the 24-hour timekeeping system (including optional time zone information), time intervals and combinations thereof. The standard does not assign any specific meaning to elements of the date/time to be represented; the meaning will depend on the context of its use. In addition, dates and times to be represented cannot include words with no specified numerical meaning in the standard (e.g., names of years in the Chinese calendar) or that do not use characters (e.g., images, sounds).

Extension mechanisms for DNS

Extension mechanisms for DNS (EDNS) is a specification for expanding the size of several parameters of the Domain Name System (DNS) protocol which had size restrictions that the Internet engineering community deemed too limited for increasing functionality of the protocol. The first set of extensions was published in 1999 by the Internet Engineering Task Force as RFC 2671, also known as EDNS0.

Motivation

The Domain Name System was first developed in the early 1980s, since which time it has been progressively enhanced with new features, while maintaining compatibility with earlier versions of the protocol.

The restrictions in size of several flags fields, return codes and label types available in the basic DNS protocol were not sufficient to support some desirable features. Moreover, DNS messages carried by UDP were restricted to 512 bytes, not considering the Internet Protocol (IP) and transport layer headers. Resorting to a virtual circuit transport, using the Transmission Control Protocol (TCP), would greatly increase overhead. This presented a major obstacle to adding new features to DNS. In 1999, Paul Vixie proposed extending DNS to allow for new flags and response codes, and to provide support for longer responses in a framework that is backwards compatible with previous implementations.

Vim (text editor)

Vim (/vɪm/; a contraction of Vi IMproved) is a clone of Bill Joy's vi editor for Unix. It was written by Bram Moolenaar based on source for a port of the Stevie editor to the Amiga and first released publicly in 1991. Vim is designed for use both from a command-line interface and as a standalone application in a graphical user interface. Vim is free and open source software and is released under a license that includes some charityware clauses, encouraging users who enjoy the software to consider donating to children in Uganda. The license is compatible with the GNU General Public License.

Although Vim was originally released for the Amiga, Vim has since been developed to be cross-platform, supporting many other platforms. In 2006, it was voted the most popular editor amongst Linux Journal readers.

History

Bram Moolenaar began working on Vim for the Amiga computer in 1988. Moolenaar first publicly released Vim (v1.14) in 1991. Vim was based on an earlier editor, Stevie, for the Atari ST, created by Tim Thompson, Tony Andrews and G.R. (Fred) Walter.

Vim (cleaning product)

Vim is the name of a range of household cleaning products originally produced by Lever Brothers. The Vim brand is currently owned by European multi-national Spotless Group.

History

Vim scouring powder, one of the first products created by William Lever, first appeared on the market in 1904, an offshoot of Monkey Brand scouring soap. The name is thought to derive from the colloquial English word "vim" which has the same meaning as the Latin vis, vim ("force", "vigour").

Vim was produced at Port Sunlight near Liverpool, England. The name Vim remained solely associated with the scouring powder until 1993 when a range of associated products were released. Vim was also the name of a detergent tablet manufactured by Lever Brothers and sold in the United States during the 1960s. It was the sponsor of the CBS sitcom The Lucy Show starring Lucille Ball .

Former owner Unilever abandoned Vim in favour of rival product Jif, although it was still sold in some other European countries.

Vimentin

Vimentin is a protein that in humans is encoded by the VIM gene.

Vimentin is a type III intermediate filament (IF) protein that is expressed in mesenchymal cells. IF proteins are found in all metazoan cells as well as bacteria. IF, along with tubulin-based microtubules and actin-based microfilaments, comprise the cytoskeleton. All IF proteins are expressed in a highly developmentally-regulated fashion; vimentin is the major cytoskeletal component of mesenchymal cells. Because of this, vimentin is often used as a marker of mesenchymally-derived cells or cells undergoing an epithelial-to-mesenchymal transition (EMT) during both normal development and metastatic progression.

Structure

A vimentin monomer, like all other intermediate filaments, has a central α-helical domain, capped on each end by non-helical amino (head) and carboxyl (tail) domains. Two monomers are likely co-translationally expressed in a way that facilitates their formation of a coiled-coil dimer, which is the basic subunit of vimentin assembly.