Technical University of Denmark
The Technical University of Denmark simply referred to as DTU, is a university in Kongens Lyngby, just north of Copenhagen, Denmark. It was founded in 1829 at the initiative of Hans Christian Ørsted as Denmark's first polytechnic, is today ranked among Europe's leading engineering institutions. DTU, along with École Polytechnique, École Polytechnique Fédérale de Lausanne, Eindhoven University of Technology, Technical University of Munich, is a member of Eurotech Universities. DTU was founded in 1829 as the'College of Advanced Technology' with the physicist Hans Christian Ørsted a professor at the University of Copenhagen, as one of the driving forces; the inspiration was the École Polytechnique in Paris, France which Ørsted had visited as a young scientist. The new institution was inaugurated on 5 November 1829 with Ørsted as its principal, a position he held until his death in 1851; the new college's first home was two buildings in Studiestræde and St- Pederstræde in central Copenhagen. Although expanded several times, they remained inadequate and in 1890 a new building complex was inaugurated in Sølvgade in 1890.
The new buildings were designed by the architect Johan Daniel Herholdt. In 1903 the College of Advanced Technology commenced the education of electrical engineers in addition to the construction engineers, production engineers and mechanical engineers educated at the college. In the 1920s space had once again become insufficient and in 1929 the foundation stone was laid for a new school at Østervold. Completion of the building was delayed by World War II and it was not completed until 1954. From 1933 the institution was known as Danmarks tekniske Højskole, translated as the'Technical University of Denmark'. On 1 April 1994, in connection with the joining of Danmarks Ingeniørakademi and DTH, the Danish name was changed to Danmarks Tekniske Universitet, in order to include the word'University', thus giving rise to the initials DTU by which the university is known today; the formal name, Den Polytekniske Læreanstalt, Danmarks Tekniske Universitet, still includes the original name. In 1960 a decision was made to move the College of Advanced Technology to new and larger facilities in Lyngby north of Copenhagen.
They were inaugurated on 17 May 1974. On 23 and 24 November 1967 the University Computing Center hosted the NATO Science Committee's Study Group first meeting discussing the newly coined term'Software Engineering'. On 1 January 2007 the university was merged with the following Danish research centers: Forskningscenter Risø, Danmarks Fødevareforskning, Danmarks Fiskeriundersøgelser, Danmarks Rumcenter, Danmarks Transport-Forskning; the university is governed by a board consisting of 10 members: six members recruited outside the university form the majority of the board, one member is appointed by the scientific staff, one member is appointed by the administrative staff, two members are appointed by the university students. The President of DTU is appointed by the university board; the president in turn appoints deans, deans appoint heads of departments. In 2014, DTU was granted an institutional accreditation by the Danish Accreditation Institution; the institutional accreditation ensures that the quality assurance system of the institution is well-described, well-argued, well-functioning in practice.
Since DTU has no faculty senate, since the faculty is not involved in the appointment of president, deans, or department heads, the university has no faculty governance. The university is located on a plain known as Lundtoftesletten in the northeastern end of the city of Lyngby; the area was home to the airfield Lundtofte Flyveplads. The campus is divided in half by the road Anker Engelunds Vej going in the east-west direction, perpendicular to that, by two lengthy, collinear roads located on either side of a parking lot; the campus is thus divided into four parts, referred to as quadrants, numbered 1 through 4 in correspondence with the conventional numbering of quadrants in the Cartesian coordinate system with north upwards. In 2018 there were two gun shootings in the area; the shootings have happened on Lundtoftevej between cars. DTU was the subject of controversy in 2009 because the former institute director of the Department of Chemistry was a high-ranking member of Scientology. In relation to this, the university was accused of violating the principles of free speech by threatening to fire employees who voice their criticism of the institute director.
On 7 April 2010, his successor was announced, at a department meeting, as Erling Stenby, who took over as Director on 1 May 2010. Shortly thereafter, the university management threatened Rolf W. Berg with dismissal for publicly criticizing the university. In November 2007 the Times Higher Education Supplement put the university as number 130 in their ranking of the universities of the world and number 122 in 2010. In "The World's Most Innovative Universities" 2015 ranking by Thomson Reuters, DTU is ranked:No. 1 in the Nordic countries No. 43 in the World In the "engineering" category in the QS subject rankings, DTU is ranked: No. 2 in the Nordic countries No. 36 in the World On the Leiden Ranking's 2008 "crown indicator" list of Europe's 100 largest universities in terms of the number of Web of Science publications in the period 2000–2007, DTU is ranked:No. 1 in the Nordic countries No. 5 in Europe In the 2015 QS World University Rankings DTU is ranked: No. 112 in the World In the 2013 Leiden Ranking DTU is ranked: No. 45 in the World No. 7 in Europe In the 2013–2014 Times Hi
Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products. Blowfish provides a good encryption rate in software and no effective cryptanalysis of it has been found to date. However, the Advanced Encryption Standard now receives more attention, Schneier recommends Twofish for modern applications. Schneier designed Blowfish as a general-purpose algorithm, intended as an alternative to the aging DES and free of the problems and constraints associated with other algorithms. At the time Blowfish was released, many other designs were proprietary, encumbered by patents or were commercial or government secrets. Schneier has stated that, "Blowfish is unpatented, will remain so in all countries; the algorithm is hereby placed in the public domain, can be used by anyone."Notable features of the design include key-dependent S-boxes and a complex key schedule. Blowfish has a variable key length from 32 bits up to 448 bits.
It uses large key-dependent S-boxes. In structure it resembles CAST-128; the adjacent diagram shows Blowfish's encryption routine. Each line represents 32 bits. There are five subkey-arrays: four 256-entry S-boxes; every round r consists of 4 actions: The F-function splits the 32-bit input into four eight-bit quarters, uses the quarters as input to the S-boxes. The S-boxes produce 32-bit output; the outputs are added XORed to produce the final 32-bit output. After the 16th round, undo the last swap, XOR L with K18 and R with K17. Decryption is the same as encryption, except that P1, P2, …, P18 are used in the reverse order; this is not so obvious because xor is associative. A common misconception is to use inverse order of encryption as decryption algorithm. Blowfish's key schedule starts by initializing the P-array and S-boxes with values derived from the hexadecimal digits of pi, which contain no obvious pattern; the secret key is byte by byte, cycling the key if necessary, XORed with all the P-entries in order.
A 64-bit all-zero block is encrypted with the algorithm as it stands. The resultant ciphertext replaces P1 and P2; the same ciphertext is encrypted again with the new subkeys, the new ciphertext replaces P3 and P4. This continues, replacing all the S-box entries. In all, the Blowfish encryption algorithm will run 521 times to generate all the subkeys - about 4KB of data is processed; because the P-array is 576 bits long, the key bytes are XORed through all these 576 bits during the initialization, many implementations support key sizes up to 576 bits. The reason for, a discrepancy between the original Blowfish description, which uses 448-bit key, its reference implementation, which uses 576-bit key; the test vectors for verifying third party implementations were produced with 576-bit keys. When asked which Blowfish version is the correct one, Bruce Schneier answered: "The test vectors should be used to determine the one true Blowfish". Another opinion is that the 448 bits limit is here to ensure that every bit of every subkey depends on every bit of the key, as the last four values of the P-array don't affect every bit of the ciphertext.
This point should be taken in consideration for implementations with a different number of rounds, as though it increases security against an exhaustive attack, it weakens the security guaranteed by the algorithm. And given the slow initialization of the cipher with each change of key, it is granted a natural protection against brute-force attacks, which doesn't justify key sizes longer than 448 bits. Blowfish is a fast block cipher, except; each new key requires pre-processing equivalent to encrypting about 4 kilobytes of text, slow compared to other block ciphers. This is not a problem in others. In one application Blowfish's slow key changing is a benefit: the password-hashing method used in OpenBSD uses an algorithm derived from Blowfish that makes use of the slow key schedule. See key stretching. Blowfish has a memory footprint of just over 4 kilobytes of RAM; this constraint is not a problem for older desktop and laptop computers, though it does prevent use in the smallest embedded systems such as early smartcards.
Blowfish was one of the first secure block ciphers not subject to any patents and therefore available for anyone to use. This benefit has contributed to its popularity in cryptographic software. Bcrypt is a password hashing function which, combined with a variable number of iterations, exploits the expensive key setup phase of Blowfish to increase the workload and duration of hash calculations, further reducing threats from brute force attacks. Bcrypt is the name of a cross-platform file encryption utility implementing Blowfish developed in 2002. Blowfish's use of a 64-bit block size makes it vulnerable to birthday attacks in contexts like HTTPS. In 2016, the SWEET32 attack demonstrated how to leverage birthday attacks to perform plaintext recovery against ciphers with a 64-bit block size; the GnuPG project recommends that Blowfish not be used to encrypt files larger than 4 GB
In cryptography, RC6 is a symmetric key block cipher derived from RC5. It was designed by Ron Rivest, Matt Robshaw, Ray Sidney, Yiqun Lisa Yin to meet the requirements of the Advanced Encryption Standard competition; the algorithm was one of the five finalists, was submitted to the NESSIE and CRYPTREC projects. It was a proprietary algorithm, patented by RSA Security. RC6 proper has a block size of 128 bits and supports key sizes of 128, 192, 256 bits up to 2040-bits, like RC5, it may be parameterised to support a wide variety of word-lengths, key sizes, number of rounds. RC6 is similar to RC5 in structure, using data-dependent rotations, modular addition, XOR operations. Note that the key expansion algorithm is identical to that of RC5; the only difference is. In August 2016, code reputed to be Equation Group or NSA "implants" for various network security devices was disclosed; the accompanying instructions revealed that some of these programs use RC6 for confidentiality of network communications.
As RC6 has not been selected for the AES, it was not guaranteed. As of January 2017, a web page on the official web site of the designers of RC6, RSA Laboratories, states the following: "We emphasize that if RC6 is selected for the AES, RSA Security will not require any licensing or royalty payments for products using the algorithm"; the emphasis on the word "if" suggests that RSA Security Inc. may have required licensing and royalty payments for any products using the RC6 algorithm. RC6 was a patented encryption algorithm. Pavan, R. L.. J. B.. Y. L.. "The RC6 Block Cipher". V1.1. Retrieved 2015-08-02. Beuchat, Jean-Luc. "FPGA Implementations of the RC6 Block Cipher". Archived from the original on 2006-05-05. Thompson, Iain. "How the NSA hacks PCs, routers, hard disks'at speed of light': Spy tech catalog leaks". The Register. Retrieved 2015-08-02. "Cryptography - 256 bit Ciphers: Reference source code and submissions to international cryptographic designs contests"."Symmetric Ciphers: RC6". Standard Cryptographic Algorithm Naming.
2009-04-15."RC6® Block Cipher". RSA Laboratories
Media Key Block
The Media Key Block is one of the keys included inside the copying protection system AACS. This system is used to protect HD DVD formats from being copied; the system was developed by companies from the film industry and the electronics industry including IBM, Microsoft, Sony, The Walt Disney Company and Warner Bros. The MKB key is found in the physical support together with the content of the disc encrypted; the MKB has the function of validating the reproduction devices on which the disc is being played and obtaining, from the devices codes, the key that will allow the decryption of the disc content. That is the Media Key. Blu-Ray or HD-DVD have as content the encrypted data, the Volume ID, the Encrypted Title Key and the MKB; the MKB is found encrypted in the disc to prevent it from being extracted off the disc and being manipulated and/or reproduced by another non authorized device. The reproduction device will have available its own keys, uniques for each model, called Device Keys; these keys are conceded by the AACS organization.
In the moment of the reproduction, one of these keys will decrypt the MKB contained on the disc and as a result of this process we obtain the Media key. The Media key is combined together as a result we obtain the Volume Unique Key. With the Kvu we are able to decrypt the Encrypted Title Key and obtain the Title keys which allows to decrypt the content of the disc and view it; this way the system can protect contents from being viewed in devices. Therefore, the system allows modifying the MKB in future relaunch of a determined content in order to select the devices in which this content can be viewed. Though it seems a simple mechanism the MKB key, found in the physical support of the disc follows a complex structure; the MKB is distributed in blocks that contain the version of the Media key, the list of devices that have been revoked, a field to authenticate the MKB, other fields that specify parameters corresponding to the decrypting algorithm and define the structure of the own Media Key and the Media key itself.
The MKB itself is found inside the field Media Key Data Record and has a variable length but it is always a multiple of 4 bytes. Many consumers associations have complained against this protection system since it can lead to a situation where physical devices cannot reproduce contents though they do not infringe any intellectual property; this situation can be achieved either by trying to reproduce some content in old devices, therefore not certified by the AACS, or because the device model has been disallowed by AACS, as a result all the owners of that device model will not be able to view contents protected with the MKB. This situation has become worse with the recent publication in multiple web sites of the Media Key, that is, the key that allows decrypting the Volume ID and at the same time, the encrypted content, without the need of using a certified device by the AACS or a valid MKB; this is critical because nowadays the Volume ID is the same in all the Blu-ray or HD-DVDs with equal content.
AACS web page. Guide to understand AACS. Introduction and Common Cryptographic Elements. Rev. 0.91. AACS Technical Overview. 7/2004
Peer review is the evaluation of work by one or more people with similar competences as the producers of the work. It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are used to maintain quality standards, improve performance, provide credibility. In academia, scholarly peer review is used to determine an academic paper's suitability for publication. Peer review can be categorized by the type of activity and by the field or profession in which the activity occurs, e.g. medical peer review. Professional peer review focuses on the performance of professionals, with a view to improving quality, upholding standards, or providing certification. In academia, peer review is used to inform in decisions related to faculty tenure. Henry Oldenburg was a British philosopher, seen as the'father' of modern scientific peer review. WA prototype is a professional peer-review process recommended in the Ethics of the Physician written by Ishāq ibn ʻAlī al-Ruhāwī.
He stated that a visiting physician had to make duplicate notes of a patient's condition on every visit. When the patient was cured or had died, the notes of the physician were examined by a local medical council of other physicians, who would decide whether the treatment had met the required standards of medical care. Professional peer review is common in the field of health care, where it is called clinical peer review. Further, since peer review activity is segmented by clinical discipline, there is physician peer review, nursing peer review, dentistry peer review, etc. Many other professional fields have some level of peer review process: accounting, engineering and forest fire management. Peer review is used in education to achieve certain learning objectives as a tool to reach higher order processes in the affective and cognitive domains as defined by Bloom's taxonomy; this may take a variety of forms, including mimicking the scholarly peer review processes used in science and medicine.
Scholarly peer review is the process of subjecting an author's scholarly work, research, or ideas to the scrutiny of others who are experts in the same field, before a paper describing this work is published in a journal, conference proceedings or as a book. The peer review helps the publisher decide whether the work should be accepted, considered acceptable with revisions, or rejected. Peer review requires a community of experts in a given field, who are qualified and able to perform reasonably impartial review. Impartial review of work in less narrowly defined or inter-disciplinary fields, may be difficult to accomplish, the significance of an idea may never be appreciated among its contemporaries. Peer review is considered necessary to academic quality and is used in most major scholarly journals, but it by no means prevents publication of invalid research. Traditionally, peer reviewers have been anonymous, but there is a significant amount of open peer review, where the comments are visible to readers with the identities of the peer reviewers disclosed as well.
The European Union has been using peer review in the "Open Method of Co-ordination" of policies in the fields of active labour market policy since 1999. In 2004, a program of peer reviews started in social inclusion; each program sponsors about eight peer review meetings in each year, in which a "host country" lays a given policy or initiative open to examination by half a dozen other countries and the relevant European-level NGOs. These meet over two days and include visits to local sites where the policy can be seen in operation; the meeting is preceded by the compilation of an expert report on which participating "peer countries" submit comments. The results are published on the web; the United Nations Economic Commission for Europe, through UNECE Environmental Performance Reviews, uses peer review, referred to as "peer learning", to evaluate progress made by its member countries in improving their environmental policies. The State of California is the only U. S. state to mandate scientific peer review.
In 1997, the Governor of California signed into law Senate Bill 1320, Chapter 295, statutes of 1997, which mandates that, before any CalEPA Board, Department, or Office adopts a final version of a rule-making, the scientific findings and assumptions on which the proposed rule are based must be submitted for independent external scientific peer review. This requirement is incorporated into the California Health and Safety Code Section 57004. Medical peer review may be distinguished in 4 classifications: 1) clinical peer review. Additionally, "medical peer review" has been used by the American Medical Association to refer not only to the process of improving quality and safety in health care organizations, but to the process of rating clinical behavior or compliance with professional society membership standards. Thus, the terminology has poor standardization and specificity as a database search term. To an outsider, the anonymous, pre-publication peer review process is opaque. Certain journals are accused of not carrying out stringent peer review in order to more expand their customer base in journals where authors pay a fee before public
Digital video recorder
A digital video recorder is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to disk recording, portable media players and TV gateways with recording capability, digital camcorders. Personal computers are connected to video capture devices and used as DVRs. Many DVRs are classified as consumer electronic devices. Consumer digital video recorders ReplayTV and TiVo were launched at the 1999 Consumer Electronics Show in Las Vegas, Nevada. Microsoft demonstrated a unit with DVR capability, but this did not become available until the end of 1999 for full DVR features in Dish Network's DISHplayer receivers. TiVo shipped their first units on March 31, 1999. ReplayTV won the "Best of Show" award in the video category with Netscape co-founder Marc Andreessen as an early investor and board member, but TiVo was more successful commercially. Legal action by media companies forced ReplayTV to remove many features such as automatic commercial skip and the sharing of recordings over the Internet, but newer devices have regained these functions while adding complementary abilities, such as recording onto DVDs and programming and remote control facilities using PDAs, networked PCs, Web browsers.
In contrast to VCRs, hard-disk based digital video recorders make "time shifting" more convenient and allow for functions such as pausing live TV, instant replay, chasing playback and skipping over advertising during playback. Many DVRs use the MPEG format for compressing the digital video. Video recording capabilities have become an essential part of the modern set-top box, as TV viewers have wanted to take control of their viewing experiences; as consumers have been able to converge increasing amounts of video content on their set-tops, delivered by traditional'broadcast' cable and terrestrial as well as IP networks, the ability to capture programming and view it whenever they want has become a must-have function for many consumers. At the 1999 CES, Dish Network demonstrated the hardware that would have DVR capability with the assistance of Microsoft software. Which included WebTV Networks internet TV. By the end of 1999 the Dishplayer had full DVR capabilities and within a year, over 200,000 units were sold.
In the UK, digital video recorders are referred to as "plus boxes". Freeview+ have been around in the UK since the late 2000s. British Sky Broadcasting markets a popular combined receiver and DVR as Sky+. TiVo launched a UK model in 2000, is no longer supported, except for third party services, the continuation of TiVo through Virgin Media in 2010. South African based Africa Satellite TV beamer Multichoice launched their DVR, available on their DStv platform. In addition to ReplayTV and TiVo, there are a number of other suppliers of digital terrestrial DVRs, including Thomson, Fusion, Pace Micro Technology, Humax, VBox Communications, AC Ryan Playon and Advanced Digital Broadcast. Many satellite, cable and IPTV companies are incorporating digital video recording functions into their set-top box, such as with DirecTiVo, DISHPlayer/DishDVR, Scientific Atlanta Explorer 8xxx from Time Warner, Total Home DVR from AT&T U-verse, Motorola DCT6412 from Comcast and others, Moxi Media Center by Digeo, or Sky+.
Astro introduced their DVR system, called Astro MAX, the first PVR in Malaysia but was phased out two years after its introduction. In the case of digital television, there is no encoding necessary in the DVR since the signal is a digitally encoded MPEG stream; the digital video recorder stores the digital stream directly to disk. Having the broadcaster involved with, sometimes subsidizing, the design of the DVR can lead to features such as the ability to use interactive TV on recorded shows, pre-loading of programs, or directly recording encrypted digital streams, it can, however force the manufacturer to implement non-skippable advertisements and automatically expiring recordings. In the United States, the FCC has ruled that starting on July 1, 2007, consumers will be able to purchase a set-top box from a third-party company, rather than being forced to purchase or rent the set-top box from their cable company; this ruling only applies to "navigation devices," otherwise known as a cable television set-top box, not to the security functions that control the user's access to the content of the cable operator.
The overall net effect on digital video recorders and related technology is unlikely to be substantial as standalone DVRs are readily available on the open market. In Europe Free-To-Air and Pay TV TV gateways with multiple tuners have whole house recording capabilities allowing recording of TV programs to Network Attached Storage or attached USB storage, recorded programs are shared across the home network to tablet, smartphone, PC, Smart TV. In 2003 many Satellite and Cable providers introduced dual-tuner digital video recorders. In the UK, BSkyB introduced their first PVR Sky+ with dual tuner support in 2001; these machines have two independent tuners within the same receiver. The main use for this feature is the capability to record a live program while watching another live program or
Digital rights management
Digital rights management tools or technological protection measures are a set of access control technologies for restricting the use of proprietary hardware and copyrighted works. DRM technologies try to control the use and distribution of copyrighted works, as well as systems within devices that enforce these policies; the use of digital rights management is not universally accepted. Proponents of DRM argue that it is necessary to prevent intellectual property from being copied just as physical locks are needed to prevent personal property from being stolen, that it can help the copyright holder maintain artistic control, that it can ensure continued revenue streams; those opposed to DRM contend there is no evidence that DRM helps prevent copyright infringement, arguing instead that it serves only to inconvenience legitimate customers, that DRM helps big business stifle innovation and competition. Furthermore, works can become permanently inaccessible if the DRM scheme changes or if the service is discontinued.
DRM can restrict users from exercising their legal rights under the copyright law, such as backing up copies of CDs or DVDs, lending materials out through a library, accessing works in the public domain, or using copyrighted materials for research and education under the fair use doctrine. The Electronic Frontier Foundation and the Free Software Foundation consider the use of DRM systems to be an anti-competitive practice. Worldwide, many laws have been created which criminalize the circumvention of DRM, communication about such circumvention, the creation and distribution of tools used for such circumvention; such laws are part of the United States' Digital Millennium Copyright Act, the European Union's Copyright Directive. The rise of digital media and analog-to-digital conversion technologies has vastly increased the concerns of copyright-owning individuals and organizations within the music and movie industries. While analog media lost quality with each copy generation, in some cases during normal use, digital media files may be duplicated an unlimited number of times with no degradation in the quality.
The rise of personal computers as household appliances has made it convenient for consumers to convert media in a physical, analog or broadcast form into a universal, digital form for portability or viewing later. This, combined with the Internet and popular file-sharing tools, has made unauthorized distribution of copies of copyrighted digital media much easier. In 1983, a early implementation of Digital Rights Management was the Software Service System devised by the Japanese engineer Ryuichi Moriya. and subsequently refined under the name superdistribution. The SSS was based on encryption, with specialized hardware that controlled decryption and enabled payments to be sent to the copyright holder; the underlying principle of the SSS and subsequently of superdistribution was that the distribution of encrypted digital products should be unrestricted and that users of those products would not just be permitted to redistribute them but would be encouraged to do so. Common DRM techniques include restrictive licensing agreements: The access to digital materials and public domain is restricted to consumers as a condition of entering a website or when downloading software.
Encryption, scrambling of expressive material and embedding of a tag, designed to control access and reproduction of information, including backup copies for personal use. DRM technologies enable content publishers to enforce their own access policies on content, such as restrictions on copying or viewing; these technologies have been criticized for restricting individuals from copying or using the content such as by fair use. DRM is in common use by the entertainment industry. Many online music stores, such as Apple's iTunes Store, e-book publishers and vendors, such as OverDrive use DRM, as do cable and satellite service operators, to prevent unauthorized use of content or services. However, Apple dropped DRM from all iTunes music files around 2009. Industry has expanded the usage of DRM to more traditional hardware products, such as Keurig's coffeemakers, Philips' light bulbs, mobile device power chargers, John Deere's tractors. For instance, tractor companies try to prevent farmers from making DIY repairs under usage of DRM-laws as DMCA.
Computer games sometimes use DRM technologies to limit the number of systems the game can be installed on by requiring authentication with an online server. Most games with this restriction allow three or five installs, although some allow an installation to be'recovered' when the game is uninstalled; this not only limits users who have more than three or five computers in their homes, but can prove to be a problem if the user has to unexpectedly perform certain tasks like upgrading operating systems or reformatting the computer's hard drive, tasks which, depending on how the DRM is implemented, count a game's subsequent reinstall as a new installation, making the game unusable after a certain period if it is only used on a single computer. In mid-2008, the Windows version of Mass Effect marked the start of a wave of titles making use of SecuROM for DRM and requiring authentication with a server; the use of t