Pretty Good Privacy is an encryption program that provides cryptographic privacy and authentication for data communication. PGP is used for signing and decrypting texts, e-mails, files and whole disk partitions and to increase the security of e-mail communications. Phil Zimmermann developed PGP in 1991. PGP and similar software follow the OpenPGP, an open standard of PGP encryption software, standard for encrypting and decrypting data. PGP encryption uses a serial combination of hashing, data compression, symmetric-key cryptography, public-key cryptography; each public key is bound to an e-mail address. The first version of this system was known as a web of trust to contrast with the X.509 system, which uses a hierarchical approach based on certificate authority and, added to PGP implementations later. Current versions of PGP encryption include both options through an automated key management server. A public key fingerprint is a shorter version of a public key. From a fingerprint, someone can get the right corresponding public key.
A fingerprint like C3A6 5E46 7B54 77DF 3C4C 9790 4D22 B3CA 5B32 FF66 can be printed on a business card. As PGP evolves, versions that support newer features and algorithms are able to create encrypted messages that older PGP systems cannot decrypt with a valid private key. Therefore, it is essential that partners in PGP communication understand each other's capabilities or at least agree on PGP settings. PGP can be used to send messages confidentially. For this, PGP uses hybrid cryptosystem by combining symmetric-key encryption and public-key encryption; the message is encrypted using a symmetric encryption algorithm, which requires a symmetric key generated by the sender. The symmetric key is used only once and is called a session key; the message and its session key are sent to the receiver. The session key must be sent to the receiver so they know how to decrypt the message, but to protect it during transmission it is encrypted with the receiver's public key. Only the private key belonging to the receiver can decrypt the session key, use it to symmetrically decrypt the message.
PGP supports integrity checking. The latter is used to detect whether a message has been altered since it was completed and the former, to determine whether it was sent by the person or entity claimed to be the sender; because the content is encrypted, any changes in the message will result in failure of the decryption with the appropriate key. The sender uses PGP to create a digital signature for the message with either the RSA or DSA algorithms. To do so, PGP computes a hash from the plaintext and creates the digital signature from that hash using the sender's private key. Both when encrypting messages and when verifying signatures, it is critical that the public key used to send messages to someone or some entity does'belong' to the intended recipient. Downloading a public key from somewhere is not a reliable assurance of that association. From its first version, PGP has always included provisions for distributing users' public keys in an'identity certification', constructed cryptographically so that any tampering is detectable.
However making a certificate, impossible to modify without being detected is insufficient. Users must ensure by some means that the public key in a certificate does belong to the person or entity claiming it. A given public key may be digitally signed by a third party user to attest to the association between someone and the key. There are several levels of confidence. Although many programs read and write this information, few include this level of certification when calculating whether to trust a key; the web of trust protocol was first described by Phil Zimmermann in 1992, in the manual for PGP version 2.0: As time goes on, you will accumulate keys from other people that you may want to designate as trusted introducers. Everyone else will each choose their own trusted introducers, and everyone will accumulate and distribute with their key a collection of certifying signatures from other people, with the expectation that anyone receiving it will trust at least one or two of the signatures. This will cause the emergence of a decentralized fault-tolerant web of confidence for all public keys.
The web of trust mechanism has advantages over a centrally managed public key infrastructure scheme such as that used by S/MIME but has not been universally used. Users have to be willing to accept certificates and check their validity manually or have to accept them. No satisfactory solution has been found for the underlying problem. In the OpenPGP specification, trust signatures can be used to support creation of certificate authorities. A trust signature indicates both that the key belongs to its claimed owner and that the owner of the key is trustworthy to sign other keys at one level below their own. A level 0 signature is comparable to a web of trust signature since only the validity of the key is certified. A level 1 signature is similar to the trust one has in a certificate authority because a key signed to level 1 is able to issue an unlimited number of level 0 signatures. A level 2 signature is analogous to the trust assumption users must rely on whenever they use the default
John Dering Nettleton, VC was a Rhodesian officer in the Royal Air Force during the Second World War. He is most famous for leading the Augsburg raid, a daylight attack against the MAN U-boat engine plant in Augsburg on 17 April 1942. For his role in this mission he was awarded the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. Born on 28 June 1917 in Nongoma, Natal Province, South Africa, Nettleton was the grandson of Admiral A. T. D. Nettleton, he was educated at Western Province Preparatory School in Cape Town from 1928–30. Nettleton served as a naval cadet on the General Botha training ship, for 18 months in the South African Merchant Marine, he took up civil engineering. Commissioned in the Royal Air Force in December 1938, Nettleton served with Nos. 207, 98 and 185 Squadrons before joining No. 44 Squadron flying the Handley Page Hampden. He took part in a daylight attack on Brest on 24 July 1941 and in a series of other bombing raids and was mentioned in despatches in September 1940.
Nettleton was promoted flying officer in July 1940, flight lieutenant in February 1941 and was a squadron leader by July 1941. No. 44 Squadron was based at RAF Waddington, Lincolnshire at this time and had taken delivery of Lancasters in late 1941. In 1942 a daylight bombing mission was planned by RAF Bomber Command against the MAN U-boat engine plant in Augsburg in Bavaria, responsible for the production of half of Germany's U‑boat engines, it was the first major mission flown using the new Avro Lancaster, a four engine bomber with tremendous lift, great range, a heavy defensive armament. It would be the longest low‑level penetration raid made during the course of the Second World War. Nettleton was nearing the end of his first tour, was placed in command of the mission; the operation would require the force to fly at low level to avoid detection from German radar. To prepare for the raid the two squadrons committed were pulled out of the bombing campaign against Germany to practice low level formation flying.
The Augsburg raid commenced on the afternoon of 17 April 1942, when Nettleton led six Lancaster bombers from RAF Waddington south in two flights of three. A few miles away at RAF Woodhall Spa, six more Lancasters from No. 97 Squadron took to the air and headed south as well. The two groups did not link up, not required as part of their mission. Both groups reached Selsey Bill independently, flew out over the channel and turned toward the French coast; the No. 97 Squadron group caught sight of the No. 44 Squadron aircraft as they approached the continent, but the No. 44 Squadron aircraft were running a course to the north of what was planned and the No. 97 Squadron commander chose not to close up. Shortly after Nettleton's group crossed the French coast near Dieppe, German fighters of Stab and II./JG 2, returning after intercepting a planned diversionary raid, organised to assist the bombers, attacked the No. 44 Squadron aircraft a short way inland. Four of the Lancasters were shot down. Nettleton continued towards the target, his two remaining aircraft attacked the factory, bombing it amid heavy anti aircraft fire.
Both aircraft were hit as they flew away from the target. Nettleton's aircraft limped back on three engines, his companion's Lancaster crashed. At the end of his return flight Nettleton's aircraft overflew the United Kingdom and was out over the Irish Sea before turning back and landing near Blackpool, he was awarded the Victoria Cross, gazetted on 24 April 1942. His award citation read: Squadron Leader Nettleton was the leader of one of two formations of six Lancaster heavy bombers detailed to deliver a low-level attack in daylight on the diesel engine factory at Augsburg in Southern Germany on April 17th, 1942; the enterprise was daring, the target of high military importance. To reach it and get back, some 1,000 miles had to be flown over hostile territory. Soon after crossing into enemy territory his formation was engaged by 25 to 30 fighters. A running fight ensued, his rear guns went out' of action. One by one the aircraft of his formation were shot down until in the end only his own and one other remained.
The fighters were shaken off but the target was still far distant. There was formidable resistance to be faced. With great spirit and defenseless, he held his two remaining aircraft on their perilous course and after a long and arduous flight at only 50 feet above the ground, he brought them to Augsburg. Here anti-aircraft fire of great intensity and accuracy was encountered; the two aircraft came low over the roof tops. Though fired at from point blank range, they stayed the course to drop their bombs true on the target; the second aircraft, hit by flak, burst into flames and crash-landed. The leading aircraft aircraft, though riddled with holes, flew safely back to base, the only one of the six to return. Squadron Leader Nettleton, who has undertaken many other hazardous operations, displayed unflinching determination as well as leadership and valour of the highest order." On the night of 12/13 July, Bomber Command put in a raid of 295 Lancasters against Turin in northern Italy. The object of the raid was to encourage the fascist government of Italy to withdraw from the war.
Turin was a distant target, being summer the nights were short. With limited darkness, the return to England could not be flown direct, had to be routed over the Bay of Biscay to avoid German day fighters. Flying Lancaster KM-Z, Nettleton took off from Dunholme Lodge at 10:23 pm. Another Lancaster on the mission was that of Leonard Bradfield; as dawn rose a number of Lancaste
Mesogastropoda was for many years a traditional taxonomic group of snails, an order. The order was composed of sea snails, but it included some land snails and freshwater snails, all of which were prosobranch gastropod mollusks; this order was introduced by J. Thiele in his work from 1921, it and was used for many decades subsequently. Recent research in malacology however has made it clear that Mesogastropoda was not a monophyletic taxon, because of that, the taxon is no longer included in modern classifications. Nonetheless most of the standard texts and field guides on mollusks date from the time period when this classification was still current, therefore references to mesogastropods or Mesogastropoda are encountered; the lower taxa that were traditionally contained in Mesogastropoda are now placed in the superorder Caenogastropoda. A more detailed account of the taxonomy is given in the articles on Gastropoda and Archaeogastropoda, a recent taxonomy is laid out in Taxonomy of the Gastropoda There are about 30,000 species that were included in this taxon.
Most of them are to be found in the sea, but there are numerous species in freshwater and a few occur on land. Their shells have no nacre. Most of these snails are herbivorous; the radula has seven denticles. The Mesogastropoda are, in many ways, more developed than the Archaeogastropoda. Through torsion of the intestinal mass and a spiral movement of the body, the gill, the kidney and the osphradium have disappeared on the right side; these organs exist only on the left side of the animal. The heart consists of one ventricle; the nervous system is more developed than in the Archeogastropods. The ganglia are connected with different organs through nerve pathways. In the Mesogastropoda, the excretory and the reproductive ducts are separated. Many members produce egg capsules. Here follows the taxonomy of the Mesogastropoda; the next taxonomy, used was that of to Ponder & Lindberg, 1997. The current prevailing system of taxonomy is that of Bouchet & Rocroi, 2005. Abyssochrysidae Aciculidae Aporrhaidae Mörch, 1852 Asterophilidae Chondropomidae Choristeidae Cingulopsidae Cochlostomatidae Diastomidae Cossman, 1895 Fossaridae Trachel, 1861 Hydrococcidae Iravadiidae Lacunidae Gill, 1871 Littorinidae Gray, 1840 Melanopsidae Micromelaniidae Omalaxidae Paedophoropodidae Pilidae Pomatiopsidae Pseudosacculidae Stenothyridae Stiliferidae Struthiolariidae Syrnolopsidae Trachysmidae Trochaclisidae Superfamily Cyclophoroidea Superfamily Viviparoidea Thiele, J. 1929-1935.
Handbuch der Systematischen Weichtierkunde. 2 vols. 1154 p. 584 figs "Classification of Gastropoda". Archived from the original on 2001-09-06. Retrieved 2017-05-07
B-Rock 99.3FM is a local radio station in Bathurst, New South Wales, Australia. It broadcasts on 99.3 megahertz on the FM band, from a transmitter in Bathurst, with a power output of 10 kilowatts and callsign 2BXS. Its callsign meaning is: an extension of its sister station's callsign. However, this callsign is never heard on air, its on-air name, B-Rock, is named for Australian motor racing legend Peter Brock, but can be known to be short for Bathurst Rock. It is owned by Bathurst Broadcasters Pty. Ltd. a held company, owned by local businessman Ron Camplin, who owns sister station 2BS Bathurst. It began broadcasting on 2 December 1996, as a supplementary FM license in the Bathurst district. B-Rock's format is hot adult contemporary, with a core audience of up to 39 years, its programs are produced locally, features competitions, comedy and national news which airs on the hour from 7 am to 5 pm Monday to Friday. List of radio stations in Australia B-Rock FM webpage
Larchmont is a historic house at 36 Butler Street in Worcester, Massachusetts. Built in 1858 as a country house, it is one of the city's finest surviving examples of Italianate architecture, it was listed on the National Register of Historic Places in 1980. Larchmont is located in a residential area of southern Worcester, on the north side of Butler Street west of McKeon Road, it is a 2-1/2 story wood frame structure, with a gabled roof and exterior finished in aluminum siding with wooden trim. Roof eaves are studded with paired Italianate brackets The front facade is three bays wide, with the center bay projecting and capped by a gable; the main entrance is at the base of this bay, sheltered by an enclosed porch. The window above is Palladian in form, with a projecting bracketed cornice. Ground floor windows on either side of the entrance have projecting cornices, while second-floor windows have moulded surrounds with bracketed sills. A porte-cochere extends to the left side of the house; the house was built in 1858 as a country house for Ransom Taylor, one of the city's largest landowners in the latter half of the 19th century.
It is a rare surviving Italianate villa, of a type that once dotted the hills of Worcester, is one of the finest Italianate houses in the city. The house may have been designed by Ball; the building's original octagonal cupola has been removed, the porte cochere is a addition. National Register of Historic Places listings in eastern Worcester, Massachusetts
Wulffite is an alkali copper sulfate, chemical formula K3NaCu4O24, in the sulfate category of minerals. It was discovered in Kamchatka, Russia at the Tolbachik volcano in 2012, it was named for Russian crystallographer Georgiy Viktorovich Wulff, he was a renowned expert who furthered X-ray diffraction and interference. Wullfite shares many similarities to Parawulffite, found in the same area just with different chemical composition. Wulffite is a fumarolic, mineral which forms in or near volcanic activity, it has been recorded to associate with hematite, calciolangbeinite, krasheninnikovite, labberite-β, bradaczekite, fluoborite, gahnite and fluorophlogopite. Wulffite has been found to reside about a meter down in between layers of basalt scoria and small 2-inch volcanic plutons, otherwise known as volcanic bombs, where most of the common chemicals are sulfates and oxides. Wulffite was found in abundance at the active monogenetic volcanic Arsenatnaya fumarole where the temperature ranged from 360-380ºC where Wulffite was found to form, but with other nearby fumaroles reaching temperatures up to 430ºC.
The fumarole showed through analysis that atmospheric air interacts with the fumarole, enriching it in H2O, HF, HCl, SO2, CO2. The Tolbachik volcano in Russia at 55º41´N 160º14´E, at an elevation of 1200 meters, is so far the only place to have Wulffite occurring. Wulffite is an exhalation mineral with its clear crystals being brittle with a Mohs hardness of just 2½, they form individually or in coarse clusters and crusts of elongated prismatic crystals reaching a maximum size of 2 mm long and 1.2 mm thick with groups of clusters stretching 1 cm across. Wulffite has two directions of perfect cleavage parallel to the positive elongation and another on the direction, it tends to fracture in a steeped pattern. The crystal colors take on being a dark emerald green to a bluish tinted green, dark green being the most common; the mineral has shown strong optical phenomenon of pleochroism that absorbs light and changes the color from emerald green to pale green. All of the physical properties of Wulffite can be contributed to the volcanic environment in which they formed and the amount of elements available for it to form at all.
Wulffite is specific sulfate labeled under alkali copper sulfates with its empirical formula calculated from 18 Oxygen to be Nal.08Σ2.97Σ4.01S3.99O18. Wulffite has been shown to dissolve in water showing that its bonds are weak enough to dissolve in room temperature water. Many forms of X-ray analysis were performed such as X-ray Powder Diffraction, Single Crystal Diffraction and Jeol JSM-6480LV a scanning electron microscope to find the chemical composition and crystal structure to compile the data of the new mineral; the analysis showed that Wulffite has an orthorhombic crystal system structure with a basic unit of a heteropolyhedral quasi-framework formed from Cu-O-S chains. From Chemical and Optical properties, the tests showed how the chains run along the with a center of Copper pyramids and SO4 tetrahedra. Wulffite can be distinguished from the similar Parawulffite by its difference in Cu-O-S chain structures, since Wulffite is centered around the SO4 tetrahedra and with the chains being interconnected instead of distorted.
Wulffite was discovered to be lacking in common bands of BO3, CO3, NO3, hydrogen groups. With the distinctive chemical banding missing and the specific environment in which they form, making Wulffite a good index mineral. List of Minerals