Ultra

Broken Enigma messages are still extremely valuable today, as they provide some of the best surviving direct accounts of the Nazi war effort. Alternatively, Microchip offers COM port emulation firmware for their range of USB PIC microcontrollers. Marian Rejewski wrote a number of papers on his 1932 break into Enigma and his subsequent work on the cipher, well into World War II, with his fellow mathematician-cryptologists, Jerzy Różycki and Henryk Zygalski; most of Rejewski's papers appear in Władysław Kozaczuk's 1984 Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War Two (edited and translated by Christopher Kasparek), which remains the standard reference on the crucial foundations laid by the Poles for World War II Enigma decryption. FTDI Chip provides virtual COM drivers with its chips, to make the USB device look to the host software like a COM (RS-232) port. Information on British cryptology appears in the official history of British intelligence in World War II, edited by Sir Harry Hinsley; he also co-edited, with Alan Stripp, a volume of memoirs by participants in the British cryptological effort, Codebreakers: the Inside Story of Bletchley Park (1993). If your Operating System and language combination is not supported, another option is a USB to RS-232 bridge. A brief description of the Enigma, as well as other codes/ciphers, can be found in Simon Singh's The Code Book (1999). Communication between software and USB devices depends upon the Operating System (Windows, Macintosh, Linux etc) and the language you choose (Java, C++, Delphi etc).

David Kahn's Seizing the Enigma (1991) is essentially about the solution of Naval Enigma, based on seizures of German naval vessels; British success in the endeavor almost certainly saved Britain from defeat in the crucial Battle of the Atlantic and thereby made the United States' entry into the war's European theater possible. See http://www.usb.org/developers/wusb/ for more details. Hugh Sebag-Montefiore's Enigma: the Battle for the Code (2000), which focuses largely on Naval Enigma, includes some previously unknown information—and many photographs of individuals involved; Bletchley Park had been his grandfather's house before it was purchased for GC&CS. Wireless USB is well suited to wireless connection of PC centric devices, just as Bluetooth is now widely used for mobile phone centric personal networks (at much lower data rates). A short account of World War II cryptology is Battle of Wits (2000) by Stephen Budiansky; it covers more than just the Enigma story. Wireless USB is intended as a cable-replacement technology, and will use Ultra wideband wireless technology for data rates of up to 480 Mbit/s. A fictional version of this story is told in the novel Enigma by Robert Harris (ISBN 0099992000), the movie made from the novel—see "Enigma (2001 film)"—and is somewhat covered, also fictionally, in Neal Stephenson's Cryptonomicon (ISBN 0099410672). The USB Implementers Forum is working on a wireless networking standard based on the USB protocol.

It was, in fact, a very narrow shave, and the reader may like to ponder [...] whether [...] we might have won [without] Ultra.". And [Powered USB] uses standard USB signalling with the addition of extra power lines for Point of sale terminals. "Let no one be fooled," Winterbotham admonishes in chapter 3, "by the spate of television films and propaganda which has made the war seem like some great triumphant epic. (However, Microsoft uses standard USB 2.0 connectivity in its newer Xbox 360.) Similarly IBM UltraPort uses standard USB signalling, but uses a proprietary connection format. Winterbotham, the first author to limn, in his 1974 book The Ultra Secret, the influence of Enigma decryption on the course of World War II, likewise made the earliest contribution to an appreciation of Ultra's postwar influence, which now continues into the 21st century — and not only in the postwar establishment of Britain's GCHQ (Government Communication Headquarters) and the United States' NSA (National Security Agency). Microsoft's Xbox game console uses standard USB 1.1 signalling in its controllers, but features a proprietary connector rather than the standard USB connector. F.W. It typically uses USB as the underlying communication layer.

This directly effected his attitude to the effectiveness of the post D-Day 1944 directives (orders) to target oil installations as he did not know that it was high level German sources which was being used by the Allied high command to assess just how much it was hurting the German war effort; so Harris tended to see the directives to bomb specific oil and munitions targets as a high level command "panacea" (his word), and as a distraction from the real task of making the rubble bounce in every large German city.^[1]. The PictBridge standard allows for interconnecting consumer imaging devices. The historian Frederick Taylor argues that as Harris was not cleared to know about ULTRA, he was given some information gleaned from ENIGMA, but not where it had come from. Wireless USB uses UWB (Ultra Wide Band) as the radio technology. After D-Day with the resumption of the strategic bomber campaign over Germany, Harris remained wedded to area bombardment. Released in May 12, 2005. The destruction of city centres not only destroyed factories, houses, and railways, but damaged and degrade the telephone network, which as the war progressed forced the German armed forces to rely ever more heavily on encrypted radio traffic, which of course the Allies were able to read. IEEE 1394b also provides rates up to approximately 3.2 Gbit/s; however, the higher rates use special physical layers which are incompatible with 1394a devices.

From February 1942 when Air Marshal Arthur Harris became Commander-in-Chief of RAF Bomber Command, the RAF implemented large scale night area bombardment of German cities. However unlike USB Hi-Speed systems which can change the speeds on each branch a 1394a device on a 1394b system requires all devices to fall to 1394a speeds. Improvements to ASDIC (sonar), coupled with Hedgehog depth charges, improved the likelihood of a surface attack sinking a U-boat. S800 requires a new physical layer, but S800 nodes can be connected to existing FireWire 1394a ports, just as USB Hi-Speed nodes will operate with older full-speed hosts. Improvements to Huff-Duff (radio-triangulation equipment used as part of ELINT) meant that a U-boat's location could be found even if the messages they were sending could not be read. This provides a new mode called S800, which operates at 786.432 Mbit/s. As the air gap over the North Atlantic closed and convoys received escort-carrier protection, airborne anti-submarine aircraft became extremely efficient hunter-killers with the use of centimetric radar and airborne depth charges. In 2003, FireWire was updated with the IEEE 1394b specification.

However there were other technologies, equipment and tactics which moved the Battle of the Atlantic in the Allies' favour. Therefore if high speed transfer is what you need you should match this with a good host controller and operating system. He would later write, in Their Finest Hour (1949): "The only thing that ever really frightened me during the war was the U-boat peril." A major factor that averted Britain's defeat in the Battle of the Atlantic was her regained mastery of Naval-Enigma decryption. Reducing the maximum transfers from say the theoretical 13 per frame to 10 or 9. An exhibit in 2003 on "Secret War" at the Imperial War Museum, in London, quoted British Prime Minister Winston Churchill telling King George VI: "It was thanks to Ultra that we won the war." Churchill's greatest fear, even after Hitler had suspended Operation Sealion and invaded the Soviet Union, was that the German submarine wolf packs would succeed in strangling sea-locked Britain. In addition to this some operating systems take a conservative approach to scheduling transactions and limit the number of transfers per frame. Probably the question should be broadened to include Ultra's influence not only on the war itself, but on the postwar period as well. It is a testament to the flexibilty of the USB bus that it can handle wide variances in device performances.

There has been controversy about the influence of Allied Enigma decryption on the course of World War II. So the sustained transfer rate is a limitation of the individual device technology not the infrastructure. As with other history, but more than for most, the history of cryptology, especially its recent history, should be read carefully, due to its complexity and to possibly confusing or misleading agendas. Why then can some USB devices only sustain 34 MB/s not 55 MB/s? The main reason is usually that the devices themselves are slow and spend most of the time NAK'ing the host to indicate they are not ready - this is particularly true of memory sticks. This can be traced to a number of causes:. Furthermore, the host-centric nature of USB allows the host to allocate more bandwidth to high priority devices instead of forcing them to compete for bandwidth as in Firewire. Several are unreliable in many respects. Conversely, for USB the maximum timing model is fixed and is limited only by the host-device branch (not the entire network).

Many accounts of the Enigma-decryption story, and of other World War II cryptological happenings, have been published. The more devices on the bus the lower the peak performance. The National Security Agency retired the last of its rotor-based encryption systems, the KL-7 series, in the 1980s. The peer to peer nature of Firewire requires devices to arbitrate, which means a FireWire bus must wait until a given signal has propagated to all devices on the bus. It was decided at this point to let the cat out of the bag, and revelations about some of Bletchley Park's operations were permitted in 1974. In a multi device environment Firewire rapidly loses ground to USB: Firewire's mixed speed networks and long connection chains dramatically affect its performance. By 1970 newer, computer-based ciphers were becoming popular as the world increasingly turned to computerised communications, and the usefulness of Enigma copies (and rotor machines generally) rapidly decreased. While for USB 2.0 the rate can be higher 55 MB/s (for a single device).

The same year, David Kahn in The Codebreakers described the 1945 capture of a Naval Enigma machine from U-505 and mentioned, somewhat in passing, that Enigma messages were already being read by that time, requiring "machines that filled several buildings." In 1971 Ladislas Farago's The Game of the Foxes gave an early published version of the myth of the purloined Enigma that enabled the British (according to Farago, Alfred Dillwyn Knox) to crack the cipher (Farago mentions an Abwehr Enigma). A single Firewire device may achieve a transfer rate for Firewire 400 as high as 41 MB/s. In 1967 the Polish military historian Władysław Kozaczuk in his book Bitwa o tajemnice (Secret War) first revealed that the German Enigma had been broken by Polish cryptologists before World War II. USB transfer rates are generally higher than Firewire due to the need for Firewire devices to arbitrate for bus access. Some information about Enigma decryption did get out earlier, however. USB can require more host resources than Firewire due to the need for the host to provide the arbitration and scheduling of transactions. Switzerland even developed its own version of the Enigma, the NEMA, and used it for decades (at least into the late '70s). The signalling rate of USB 2.0 Hi-Speed mode is 480 megabits per second, while the signalling rate of FireWire 400 (IEEE 1394a) is 393.216 Mbit/s [4].

Their traffic was not so secure as they believed, however, which is of course one reason the British and Americans made the machines available. These and other differences reflect the differing design goals of the two busses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. As mentioned, after the war, surplus Enigmas and Enigma-like machines were sold to many countries around the world, which remained convinced of the security of the remarkable cipher machines. The most significant technical differences between FireWire and USB include the following:. There is also a one-volume collection of reminiscences by Ultra veterans, Codebreakers (1993), edited by Hinsley and Alan Stripp. FireWire retains its popularity in many professional settings, where it is used for audio and video transfer, and data storage. It was chiefly edited by Harry Hinsley, with one volume by Michael Howard. Today, USB Hi-Speed is rapidly replacing FireWire in consumer products.

The official history of British intelligence in World War II was published in five volumes from 1979 to 1988. The introduction of USB 2.0 Hi-Speed, with its widely advertised 480 Mbit/s signaling rate, convinced many consumers that FireWire was outdated (although this was not necessarily the case; see "USB 2.0 Hi-Speed vs FireWire" below). He was involved in Bletchley Park's intelligence analysis of decrypts, working between the cryptological operation and Winterbotham's distribution operation. However, because FireWire ports were more costly to implement than USB ports, primarily due to their per-port licence fee, they were rarely provided as standard equipment on computers, and peripheral manufacturers offered many more USB devices. Peter Calvocorressi's book, Top Secret Ultra (1980), is in this regard better written and more responsible. USB originally operated at a far lower data rate and used much simpler hardware, and was suitable for small peripherals such as keyboards and mice. He worked on the operation to distribute Ultra to end consumers and, based on the evidence of his book, did not understand much about cryptology. USB was originally seen as a complement to FireWire, which was designed as a high-speed serial bus which could efficiently interconnect peripherals such as hard disks, audio interfaces, and video equipment.

Wintherbotham's book is very interesting, but is in error on many points. Apple computers have used USB mice and keyboards exclusively since January 1999. Winterbotham, published The Ultra Secret. Mouses and keyboards are frequently fitted with USB connectors, but supplied with a small USB-to-PS/2 adaptor so that they can be used with either USB or PS/2 ports. The British ban was finally lifted in 1974, the year that a key participant on the distribution side of the Ultra project, F.W. Joysticks, keypads, tablets and other human-interface devices are also progressively migrating from MIDI, PC game port, and PS/2 connectors to USB. Nevertheless it was the public disclosure of Enigma decryption, in the book Enigma (1973) by French Intelligence officer Gustave Bertrand, that generated pressure to discuss the rest of the Enigma/Ultra story. Motherboards for non-portable PCs usually have a number of USB 2.0 high-speed ports, some available at the back of the computer case, others requiring USB sockets on the front or rear of the computer to be connected via a cable to a header on the motherboard.

Discussion by either the Polish or the French of Enigma breaks carried out early in the war would have been uninformed regarding breaks carried out during the balance of the war. AT keyboard connectors are less frequently found. Since it was British and, later, American message-breaking which had been the most extensive, this meant that the importance of Enigma decrypts to the prosecution of the war remained unknown. As of 2006, most PCs and motherboards have at least one USB port, but still retain PS/2 keyboard and mouse connectors. The third explanation is given by Winterbotham (The Ultra Secret, introduction), who recounts that two weeks after V-E Day Churchill requested that former recipients of Ultra intelligence be asked not to divulge the source or the information they had received from it, in order that there might be neither damage to the future operations of the Secret Service nor any cause for the Allies' enemies to blame it for their defeat. Additionally, when multiple devices are connected, USB has significant advantages over FireWire,. A second explanation relates to a misadventure of Winston Churchill's between the World Wars, when he publicly disclosed information obtained by decrypting Russian secret communications; this had prompted the Russians to change their cryptography, leading to a cryptological blackout. However, USB ports are more usual than Firewire on consumer-level computers, which enhances the compatibility of a USB drive.

Winterbotham's The Ultra Secret, after World War II the British gathered up all the Enigma machines they could find and sold them to Third World countries, confident that they could continue reading the messages of the machines' new owners. An operating system designed to handle Hi-Speed USB 2.0 optimally is capable of data rates higher than Firewire, but the most commonly found [early 2006] operating systems and drivers are not. First, as David Kahn pointed out in his 1974 New York Times review of F.W. Additionally, some operating systems transfer blocks limited to the USB 1.1 size of 64 bytes, without taking advantage of the larger block sizes allowed by USB 2.0. All may be true. The main reason for this is that the tests are conducted point to point (only one device) which means the USB system is always waiting for the drive. Each has plausibility. FireWire tends to perform better in speed benchmark tests than even Hi-Speed USB 2.0, although the latter supports a numerically higher bit-rate.

At least three versions exist as to why Ultra was kept secret so long. FireWire technology is also commonly used with portable hard drives; some have both USB and FireWire ports. During that period the important contributions to the war effort of a great many people remained unknown, and they were unable to share in the glory of what is likely one of the chief reasons the Allies won the war — or, at least, as quickly as they did. Functionally, the drive appears to the user just like another internal drive.. While it is obvious why Britain and the United States went to considerable pains to keep Ultra a secret until the end of the war, it has been a matter of some conjecture why Ultra was kept officially secret for 29 years thereafter, until 1974. These external drives usually contain a translating device that interfaces a drive of conventional technology (IDE, ATA, SATA, ATAPI, or even SCSI) to a USB port. The Japanese are said to have obtained an Enigma machine as early as 1937, although it is debated whether they were given it by their German ally or bought a commercial version which, except for plugboard and actual rotor wirings, was essentially the German Army / Air Force machine. Today, a number of manufacturers offer external, portable USB hard drives, or empty enclosures for drives, that offer performance comparable to internal drives.

These reports included reviews of German strategy and intentions, reports on direct inspections (in one case, of Normandy beach defenses) by the ambassador, and reports of long interviews with Hitler. However, USB has one important advantage in making it possible to install and remove devices without opening the computer case, making it useful for external drives. Some Purple decrypts proved useful elsewhere, for instance detailed reports by Japan's ambassador to Germany which were encrypted on the Purple machine. USB is not intended to be a primary bus for a computer's internal storage: buses such as ATA (IDE) and SCSI fulfill that role. It was also cracked, by the US Army's Signal Intelligence Service. This was initially intended for traditional magnetic and optical drives, but has been extended to support a wide variety of devices. In the Pacific theater, the Japanese cipher machine dubbed "Purple" by the Americans, and unrelated to the Enigmas, was used for highest-level Japanese diplomatic traffic. USB implements connections to storage devices using a set of standards called the USB mass-storage device class.

The information it provided was accurate and timely, and Soviet agents in Switzerland (including Alexander Rado, the director) eventually took it quite seriously. Those problems with the abuse of the USB power supply have inspired a number of April Fool hoaxes, like the introduction of a USB-powered George Foreman iGrill [2] and a desktop USB Fondue Set [3]. The Lucy ring was operated, apparently, by one man, Rudolf Roessler, and was initially treated with considerable suspicion by the Soviets. USB-powered devices attempting to draw large currents without requesting the power will not work with certain USB controllers, and will either disrupt other devices on the bus or fail to work themselves (or both). It has been alleged that "Lucy" was, in major part, a way for the British to feed Ultra intelligence to the Soviets in a way that made it appear to have come from highly-placed espionage and not from cryptanalysis of German radio traffic. Amongst others, a number of peripherals for IBM laptops (now made by Lenovo) are designed to use dual USB connections. This was an extremely well informed, and rapidly responsive, ring which was able to get information "directly from the German General Staff Headquarters" — often on specific request. For portable devices where external power is not available, but not more than 1 A is required at 5 V, devices may have connectors to allow the use of two USB cables, doubling available power but reducing the number of USB ports available to other devices.

An intriguing question concerns alleged use of Ultra information by the "Lucy" spy ring. Such devices can be used with an external power supply of adequate rating; some external hubs may, in practice, supply sufficient power. (See Bamford's Body of Secrets in regard to the TICOM missions immediately after the war.). This is a common requirement of external hard and optical disc drives and other devices with motors or lamps. They just found it impossible to imagine anyone going to the immense effort required. Some USB devices draw more power than is permitted by the specification for a single port. Among the things they learned was that German cryptographers, at least, understood very well that Enigma messages might be read; they knew Enigma was not unbreakable. This can cause problems with some computers—the USB specification requires that devices connect in a low-power mode (100 mA maximum) and state how much current they need, before switching, with the host's permission, into high-power mode.

After the War, American TICOM project teams found and detained a considerable number of German cryptographic personnel. In most cases, these items contain no electronic circuitry, and thus are not proper USB devices at all. Likewise, Ultra traffic suggested an attack in the Ardennes in 1944, but the Battle of the Bulge was a surprise to the Allies because the information was disregarded. The typical example is a USB-powered reading light, but fans, battery chargers (particularly for mobile telephones) and even miniature vacuum cleaners are available. Rommel's intentions just prior to the Battle of the Kasserine Pass in North Africa in 1942 had been suggested by Ultra, but this was not taken into account by the Americans. A number of devices use this power supply without participating in a proper USB network. However, Ultra information was also at times misused or ignored. The host operating system typically keeps track of the power requirements of the USB network and may warn the computer's operator when a given segment requires more power than is available (and will generally shut down devices or hubs in order to keep power consumption within the available resource).

The Germans considered Enigma traffic so secure that they openly discussed their plans and movements, handing the Allies huge amounts of information. When USB devices (including hubs) are first connected they are interrogated by the host controller, which inquires of each their maximum power requirements. Had they been better informed, they could have changed systems, forcing Allied cryptologists to start over. Devices that need more than 500 mA must provide their own power. By 1945 almost all German Enigma traffic (Wehrmacht, Navy, Luftwaffe, Abwehr, SD, etc.) could be decrypted within a day or two, yet the Germans remained confident of its security. Many hubs include external power supplies which will power devices connected through them without taking power from the bus. Intelligence from signals between Adolf Hitler and General Günther von Kluge was of considerable help during the campaign in France just after the Allied D-Day landings, particularly in regard to estimates of when German reserves might be committed to battle. This disallows connection of a bus-powered hub to another bus-powered hub.

Ultra information was of considerable assistance to the British (Montgomery being "in the know" about Ultra) at El Alamein in Western Egypt in the long-running battle with the Afrika Korps under Rommel. Bus-powered hubs can continue to distribute the bus provided power to connected devices but the USB specification only allows for a single level of bus-powered devices from a bus-powered hub. British Admiral Cunningham also did some fancy footwork at a hotel in Egypt to prevent Axis agents from taking note of his movements and deducing that a major operation was planned. A bus-powered device may use as much of that power as allowed by the port it is plugged into. Breaking of some messages (not in German Enigma) led to the defeat of the Italian Navy at Capa Matapan, and was preceded by another "fortuitous" search-plane sighting. This is often enough to power several devices, although this budget must be shared among all devices downstream of an unpowered hub. It is commonly claimed that the breaks into Naval Enigma resulted in the war being a year shorter, but given its effects on the Second Battle of the Atlantic alone, that might be an underestimate. A given segment of the bus is specified to deliver up to 500 mA.

Its traffic was routinely readable. In typical situations the voltage is close to 5 V. The U-boat network which used the four-rotor machine was known as Triton, codenamed Shark by the Allies. The compliance spec requires no more than 5.25 V anywhere and no less than 4.375 V at the worst case; a low-power function after a bus-powered hub. Realizing the error, the U-boat retransmitted the same message using the 3-rotor Enigma, giving the British sufficient clues to break the new machine soon after it became operational on February 1, 1942. In practice, delivered voltage can drop well below 5 V, to only slightly above 4 V. Fortunately for the Allies, in December a U-boat mistakenly transmitted a message using the four-rotor machine before it was due to be inaugurated. The USB connector provides a single nominally 5 volt wire from which connected USB devices may power themselves.

In 1941 British intelligence learned that the German Navy was about to introduce M4, a new version of Enigma with 4 rotors rather than 3. The maximum length of a USB cable is 5 meters; greater lengths require hubs [1]. Coincidentally, German success in this respect almost exactly matched in time an Allied blackout from Naval Enigma. Wireless USB is a standard being developed to extend the USB standard while maintaining backwards compatibility with USB 1.1 and USB 2.0 on the protocol level. The more so, since his counterintelligence B-Dienst group, who had partially broken Royal Navy traffic (including its convoy codes early in the war), supplied enough information to support the idea that the Allies were unable to read Naval Enigma. USB On-The-Go has therefore defined two small form factor connectors, the mini-A and mini-B, and a hermaphroditic socket (mini-AB), which should stop the proliferation of proprietary designs. However, the evidence was never enough to truly convince him that Naval Enigma was being read by the Allies. This facility targets units such as PDAs where the USB link might connect to a PC's host port as a device in one instance, yet connect as a host itself to a keyboard and mouse device in another instance.

Dönitz had the settings book changed anyway, blacking out Bletchley Park for a period. Even after the cable is hooked up and the units are talking, the two units may "swap" ends under program control. The analysis suggested that the signals problem, if there was one, wasn't due to the Enigma itself. An extension to USB called USB On-The-Go allows a single port to act as either a host or a device - chosen by which end of the cable plugs into the socket on the unit. Dönitz immediately asked for a review of Enigma's security. For specification purposes, these devices were treated as having a captive cable. They all escaped and reported what had happened. Other manufacturers of small items also developed their own small form factor connector, and a wide variety of these have appeared.

In one instance, three U-boats met at a tiny island in the Caribbean, and a British destroyer promptly showed up. It uses a different mechanical connector while preserving the USB signaling and protocol. Karl Dönitz received reports of "impossible" encounters between U-boats and enemy vessels which made him suspect some compromise of his communications. For example, the IBM UltraPort is a proprietary USB connector located on the top of IBM's laptop LCDs. Some Germans had suspicions that all was not right with Enigma. However, the mechanical layer has changed in some examples. In order to solve this problem the Allies, especially the US, "went industrial" and produced much larger versions of the Polish bomba that could rapidly test thousands of possible key settings. The A-plug is approximately 4x12 mm, the B-plug is approximately 7x8 mm, and the B-mini plug is approximately 3x7 mm.

The number remaining was still huge, and due to the new rotors that the Germans had added from time to time, that number was much larger than the Poles had faced. Thus all compliant USB cables have an A plug on one end, and either a B or Mini-B on the other end. However, the new tricks only reduced the number of possible settings for a message. Hosts and devices include connectors (female) while cables contain plugs (male). From this point on, Naval Enigma messages were being read constantly, even after changes to the ground settings. All connectors are mechanically incompatible, with an A connector always used on the upstream (host) end, and a B connector always used on the downstream (device) end. was likely to have been broadcast by a weather-reporting boat in the Atlantic, and that meant the message would almost certainly contain these cribs; and similarly for other traffic. The USB 2.0 specification also introduces the mini-B connector, for smaller devices such as PDAs, mobile phones or digital cameras.

Thus a brief message sent from the west at 6 a.m. The USB 1.0, 1.1 and 2.0 specifications define two types of connectors for the attachment of devices to the bus: A, and B. But by 1943 so much traffic had been decrypted that Allied cryptologists had an excellent understanding of the messages coming from various locations at various times. In particular:. Charting decrypted Enigma traffic against British shipping losses for a given month shows a strong pattern of increased losses when Naval Enigma was blacked out, and vice versa. The connectors which the USB committee specified were designed to support a number of USB's underlying goals, and to reflect lessons learned from the varied menagerie of connectors then in service. Even these brief periods were enough to markedly affect the course of the war. The Mini A also has an additional piece of plastic inside to prevent insertion into slave only device.

This technique was, at Bletchley, called gardening. This indicates if a device supporting usb on the go (with a mini AB socket) should initially act as host, in the mini B this is open circuit. In the case of mining this or that channel, they expected the word "Minen" to occur in some of the messages. Pin 4 is called ID and is connected to pin 5 for a mini-A. To do this they would drop mines (or take some other action), then listen for messages thus provoked. Most of the pins of a mini USB connector are the same as a standard USB connector, except pin 4. In other cases, the Allies induced the Germans to provide them with cribs. This segregation is for bandwidth only; bus rules about power and hub depth still apply.

More fantastic scenarios were contemplated, such as Ian Fleming's James Bondian suggestion to "crash" captured German bombers into the sea near German shipping, hoping they would be "rescued" by a ship's crew, which would be taken captive by commandos concealed in the plane who would capture the cryptographic material intact. The Transaction Translator in a Hi-Speed hub (or possibly each port depending on the electrical design) will function as a completely separate Full Speed bus to Full Speed and Low Speed devices attached to it. These included U-boats U-505 (1944) and U-559 (1942) and a number of German weather boats and converted trawlers such as the Krebs, captured during a raid on the Lofoten Islands off Norway. Hi-Speed hubs have a special function called the Transaction Translator that segregates Full Speed and Low Speed bus traffic from Hi-Speed traffic. Naval Enigma machines or settings books were captured from a total of 7 U-boats and 8 German surface ships. Hi-Speed devices should fall back to the slower data rate of Full Speed when plugged into a Full Speed hub. And it was done again shortly afterwards. All devices are tested according to the latest spec, so recently-compliant Low Speed devices are also 2.0.

On 7 May 1941 the Royal Navy deliberately captured a German weather ship, together with cipher equipment and codes; and 2 days later U-110 was captured, together with an Enigma machine, code book, operating manual and other information that enabled Bletchley Park to break submarine messages until the end of June. The USB-IF certifies devices and provides licenses to use special marketing logos for either "Basic-Speed" (low and full) or High-Speed after passing a compliancy test and paying a licensing fee. Different and far more difficult methods had to be used to break into Naval Enigma traffic, and with the U-boats running freely in the Atlantic after the fall of France, a more direct approach recommended itself. Though Hi-Speed devices are commonly referred to as "USB 2.0", not all USB 2.0 devices are Hi-Speed. A USB device should specify the speed it will use by correct labeling on the box it came in or sometimes on the device itself. There was no hint at all to the initial settings for the machines, and there was little probable plaintext to use, either. USB supports three data rates. From the beginning, the Naval version of Enigma used a larger selection of rotors than did the Army or Air Force versions, as well as operating procedures that made it much more secure than other Enigma variants. D+ and D− operate together; they are not separate simplex connections.

In the summer of 1940, British cryptanalysts, who were successfully breaking German Air Force Enigma-cypher variants, were able to give Churchill information about the issuing of maps of England and Ireland to the Sealion invasion forces. These collectively use half-duplex differential signaling to combat the effects of electromagnetic noise on longer lines. Liaison officers were appointed for each field command to manage and control dissemination. USB signals are transmitted on a twisted pair of data cables, labelled D+ and D−. The distribution of Ultra information to Allied commanders and units in the field involved considerable risk of discovery by the Germans, and great care was taken to control both the information and knowledge of how it was obtained. The most used device classes (grouped by assigned class ID) are:. The British were, it is said, more disciplined about such measures than the Americans, and this difference was a source of friction between them. These can be used as the main device classes are continuously revised.

Ultra information was used to attack and sink many Afrika Korps supply ships bound for North Africa; but, as in the North Atlantic, every time such information was used, an "innocent" explanation had to be provided: often scout planes were sent on otherwise unnecessary missions, to ensure they were spotted by the Germans. Each class also optionally supports a SubClass and Protocol subdefinition. This was taken to the extreme that, for instance, though they knew from intercepts the whereabouts of U-boats lying in wait in mid-Atlantic, the U-boats often were not hunted unless a "cover story" could be arranged — a search plane might be "fortunate enough" to sight the U-boat, thus explaining the Allied attack. If bDeviceClass is set to 0x00, the operating system will look at bInterfaceClass of each interface to determine the device class. The Allies were seriously concerned to conceal from the Axis command that they had broken into Enigma traffic. Both of these are a single byte each, so a maximum of 253 different device classes are possible (values 0x00 and 0xFF are reserved). Usable Ultra information came too late to be of great help during the Battle of Britain. If the class is to be set for the entire device, the number is assigned to the bDeviceClass field of the device descriptor, and if it is to be set for a single interface on a device, it is assigned to the bInterfaceClass field of the interface descriptor.

Instead the Germans every so often added new rotors to the mix, thereby allowing the British to work out the wirings of the newest rotors. Device classes are decided upon by the Device Working Group of the USB Implementers Forum. However, due to the expense and difficulty of getting new rotors to all ships and units, this was never done. An operating system is supposed to implement all device classes so as to provide generic drivers for any USB device. And had German operating practices been more secure, things would have been much more difficult for the British cryptologists. These classes define an expected behavior in terms of device and interface descriptors so that the same device driver may be used for any device that claims to be a member of a certain class. Had the Germans ever replaced every rotor at the same time, the British might not have been able to break back into the system. Devices that attach to the bus can be full-custom devices requiring a full-custom device driver to be used, or may belong to a device class.

Other German operators used "form letters" for daily reports, notably weather reports, so the same crib might be used every day. On BSD systems, dmesg will show the detailed information hierarchy. Analysts were set to finding such messages in the sea of daily intercepts, which winnowed out enough possibilities to allow Bletchley to use other original Polish techniques as well to find the initial daily keys. Most Linux systems also provide the lsusb command which provides USB-specific details about ports and controllers. In other cases, as they had before the war, Enigma operators would constantly use the same settings for their message keys, often their own initials or those of a girlfriend (one apparently had the initials "C.I.L.," so Bletchley Park named such hints "cillies"). On Microsoft Windows platforms, one can tell whether a USB controller is version 2.0 by opening the Device Manager and checking for the word "Enhanced" in its description; only USB 2.0 drivers will contain the word "Enhanced." On Linux systems, the lspci -v command will list all PCI devices, and controllers will be named OHCI, UHCI or EHCI respectively, which is also the case in the Mac OS X system profiler. A British analyst received from an intercept station a long message containing not a single "T" and immediately realised what had happened. All other vendors use virtual OHCI controllers.

In one instance, a clerk was asked to send a test message, and hit the T key repeatedly and transmitted the resulting letters. The virtual HCD on Intel and Via EHCI controllers are UHCI. On some occasions, German cipher clerks helped the Allied cryptanalysts. Each EHCI controller contains four virtual HCD implementations to support Full Speed and Low Speed devices. This provided a clue to message keys. Only EHCI can support high-speed transfers. With a probable plaintext fragment and the knowledge that no letter could be enciphered as itself, a corresponding ciphertext fragment could often be identified. The USB 2.0 HCD implementation is called the Extended Host Controller Interface (EHCI).

Another technique counted on common German phrases, such as "Heil Hitler" or "please respond," which were likely to occur in a given plaintext; a successful guess as to a plaintext was known at Bletchley as a crib. During the design phase of USB 2.0 the USB-IF insisted on only one implementation. One mode of attack on the Enigma relied on the fact that the reflector (a patented feature of the Enigma machines) guaranteed that no letter could be enciphered as itself, so an A could not be sent as an A. The dueling implementations forced operating system vendors and hardware vendors to develop and test on both implementations which increased cost. 31, 58.). The main difference between OHCI and UHCI is the fact that UHCI is more software-driven than OHCI is, making UHCI slightly more processor-intensive but cheaper to implement (excluding the license fees). (Kozaczuk, pp. VIA Technologies licensed the UHCI standard from Intel; all other chipset implementers use OHCI.

Even before the war, it had been a challenge to the Poles; only a portion of Naval Enigma had been read at B.S.-4 (the Cipher Bureau's German section) due to limited Bureau personnel and resources and because knowledge of army and air force traffic had been deemed more important to Poland's defense. However, Intel subsequently created a specification they called the Universal Host Controller Interface (UHCI) and insisted other implementers pay to license and implement UHCI. (For a discussion of the many identical techniques used by the Poles and the British, see Kozaczuk 1984, appendix F.) A particular challenge would be German Naval Enigma. Compaq's Open Host Controller Interface (OHCI) was adopted as the standard by the USB-IF. British attacks on the Enigmas were similar to the original Polish methods, but naturally continued evolving to keep pace with the growing complexity of German equipment and procedures. At version 1.0 and 1.1 there were two competing HCD implementations. Such information enabled the Allies to maintain an accurate picture of enemy plans and orders of battle, and when appropriately used was of great value in formulating Allied strategy and tactics. In practice, these are hardware registers (ports) in the computer.

By 1943, a large proportion of intercepts (over 2,000 daily at the height of operations) were routinely read, including some from Hitler himself. The hardware that contains the host controller and the root hub has an interface toward the programmer which is called Host Controller Device (HCD) and is defined by the hardware implementer. Among the latter was Alan Turing, one of the founders of modern computing. An endpoint may however be reused among several interfaces and alternate interface settings. The Bletchley Park workers included a mix of crossword enthusiasts, chess mavens, mathematicians and pioneer computer scientists. These interface descriptors in turn have one default interface setting and possibly more alternate interface settings which in turn have endpoint descriptors, as outlined above. Such was the secrecy surrounding reports from "Boniface" that "his" reports were taken directly to Prime Minister Winston Churchill in a locked box to which he personally held the key. Each configuration descriptor in turn has one or more interface descriptors, which describe certain aspects of the device, so that it may be used for different purposes: for example, a camera may have both audio and video interfaces.

Earlier in the war, the product from Bletchley Park was codenamed "Boniface" to give the impression to the uninitiated that the source was a secret agent. low power mode. Eventually there would be a very large organization controlling the distribution of the resulting – secret – decrypted information, which in time came to be called "Ultra." Strict rules were established to restrict the number of people who knew about the existence of Ultra in the hope of ensuring that nothing (e.g., leaks, actions) would alert the Axis powers that the Allies were reading their messages. active vs. They also set up a large interception network to collect enciphered messages for the cryptologists at Bletchley and at five near-by off-site outstations at Adstock, Gayhurst, Wavendon, Stanmore, and Eastcote. These configurations often correspond to states, e.g. (Work that would be done after the outbreak of World War II in France, at PC Bruno outside Paris, would be strictly the domain of the Polish Cipher Bureau cryptologists who had escaped Poland.) Early in 1939 Britain's secret service had installed its Government Code and Cypher School (GC&CS) at Bletchley Park, 50 miles (80 km) north of London, to work on enemy message traffic. The device connected to the bus has one (and only one) device descriptor which in turn has one or more configuration descriptors.

Armed with this Polish assistance, the British began work on German Enigma traffic. To access an endpoint, a hierarchical configuration must be obtained. Since neither the French nor the British had succeeded in breaking Enigma traffic, this was a major windfall for Poland's western allies. The interrupt transfers on corresponding endpoints does not actually interrupt any traffic on the bus, they are just scheduled to be queried more often and in between any other large transfers, thus "interrupt traffic" on a USB bus is really only high-priority traffic. This happened during the famous meeting at Pyry, in the Kabaty Woods south of Warsaw, on July 25, 1939. The host controller then polls the bus for traffic, usually in a round-robin fashion, so no device can transfer any data on the bus without explicit request from the host controller. Well before 1938, much German Enigma traffic was being routinely decrypted by the Poles; but accelerating changes in German operations (encipherment procedures, frequency of key changes, greater rotor choice) and looming war led the Poles to share their achievements in Enigma decryption with France and England. When a device (function) or hub is attached to the host controller through any hub on the bus, it is given a unique 7 bit address on the bus by the host controller.

They designed working "doubles" of the Enigmas and developed equipment and techniques which helped in finding the keys needed for decryption (including the "grill," "clock," cyclometer, cryptologic bomb, and perforated sheets). The pipes are also divided into four different categories by way of their transfer type:. Together with two colleagues at the Polish General Staff's Cipher Bureau (Polish: Biuro Szyfrów), he went on to develop practical methods of decrypting Enigma traffic. There is always an inward and an outward pipe numbered 0 on each device. The 27-year-old mathematician used advanced mathematics (group theory, particularly permutation theory) for the first time to crack the Enigma system. All USB devices have at least two such pipes/endpoints: namely endpoint 0 which is used to control the device on the bus. The fundamental break into the Enigma systems that were to be used by Nazi Germany was made in Poland in 1932, just on the eve of Adolf Hitler's accession to power, by Marian Rejewski. Each endpoint can transfer data in one direction only, either into or out of the device/function, so each pipe is uni-directional.

Dilly Knox, of GC&CS, is said to have broken it during the 1920s. Each pipe has a maximum packet length, typically 2ⁿ bytes, so a USB packet will often contain something on the order of 8, 16, 32, 64, 128, 256, 512 or 1024 bytes. The commercial versions were not so secure. In these pipes, data is transferred in packets of varying length. Each variant required different cryptanalytic treatment. (The OUT direction shall be interpreted out of the host controller and the IN direction is into the host controller.) Endpoint 0 is however reserved for the bus management in both directions and thus takes up two of the 32 endpoints. The German Army, Navy, Air Force, Nazi party, Gestapo, and German diplomats all used Enigma machines, but there were several variants (eg, the Abwehr used a four-rotor machine without a plugboard, and Naval Enigma used different key management from that of the Army or Air Force, making its traffic far more difficult to cryptanalyze). These endpoints (and their respective pipes) are numbered 0-15 in each direction, so a device/function can have up to 32 active pipes, 16 inward and 16 outward.

These messages were generated on several variants of an electro-mechanical rotor machine called "Enigma." The Enigma machine was widely thought to be in practice unbreakable in the 1920s, when a variant of the commercial Model D was first used by the German Navy. The pipes are synonymous to byte streams such as in the pipelines of Unix, however in USB lingo the term endpoint is (sloppily) used as a synonym for the entire pipe, even in the standard documentation. Ultra material largely came from German cipher traffic. These devices/functions (and hubs) have associated pipes (logical channels) which are connections from the host controller to a logical entity on the device named an endpoint. . There always exists one hub known as the root hub, which is attached directly to the host controller. Eisenhower, as at war's end describing Ultra as having been "decisive" to Allied victory in World War II. The hubs are special purpose devices that are not officially considered functions.

Winterbotham, in The Ultra Secret (1974), quotes the western Supreme Allied Commander, Dwight D. In USB terminology devices are referred to as functions, because in theory what we know as a device may actually host several functions, such as a router that is a Secure Digital Card reader at the same time. F.W. USB connects several devices to a host controller through a chain of hubs. Although the volume of messages read from this system was much smaller than that from the Enigma, they more than made up for it in their importance. The specification is at revision 1.0a (Jan 2006). It was eventually attacked using the Colossus, considered to be the forerunner of the electronic programmable digital computer. Smaller USB plugs and receptacles, called Mini-A and Mini-B, are also available, as specified by the On-The-Go Supplement to the USB 2.0 Specification.

These also were broken, particularly TUNNY, which the British thoroughly penetrated. Equipment conforming with any version of the standard will also work with devices designed to any of the previous specifications (backwards compatibility). Several distinct systems were used, principally the Lorenz SZ 40/42 (initially code-named TUNNY) and Geheimfernschreiber (code-named STURGEON). Previous notable releases of the specification were 0.9, 1.0, and 1.1. Later the Germans began to use several stream cipher teleprinter systems for their most important traffic, to which the British gave the generic code-name FISH. The USB 2.0 specification was released in April 2000 and was standardized by the USB-IF at the end of 2001. For some time thereafter, "Ultra" was used only for intelligence from this channel. Hewlett-Packard, Intel, Lucent, Microsoft, NEC, and Philips jointly led the initiative to develop a higher data transfer rate than the 1.1 specification.

Until the name "Ultra" was adopted, there were several cryptonyms for intelligence from this source, including Boniface. The USB specification is at version 2.0 (with revisions) as of February 2006. Much of the German cipher traffic was encrypted on the Enigma machine, hence the term "Ultra" has often been used almost synonymously with "Enigma decrypts.". Notable members have included Apple Computer, Hewlett-Packard, NEC, Microsoft, Intel, and Agere. The name arose because the code-breaking success was considered more important than the highest security classification available at the time (Most Secret) and so was regarded as being Ultra Secret. The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards body incorporating leading companies from the computer and electronics industries. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources. As of 2005, the only large classes of peripherals that cannot use USB, because they need a higher data rate than USB can provide, are displays and monitors, and high-quality digital video components.

Ultra (sometimes capitalised ULTRA) was the name used by the British for intelligence resulting from decryption of German communications in World War II. As of 2004 there were about 1 billion USB devices in the world. page 202. USB is also used extensively to connect non-networked printers, replacing the parallel ports which were widely used; USB simplifies connecting several printers to one computer. ISBN 0747570787. For many devices such as scanners and digital cameras, USB has become the standard connection method. ^  Fredrick Taylor Dresden:Tuesday 13 February 1945, Pub (NY): HarperCollins, ISBN 0060006765, Pub (Lon): Bloomsbury. USB can connect peripherals such as mice, keyboards, gamepads and joysticks, scanners, digital cameras, printers, external storage, networking components, etc.

Her account appears in Sebag-Montefiore's book. When a device is first connected, the host enumerates and recognises it, and loads the device driver it needs. The fate of the German Enigma spy "Asché" was not publicly known till Hugh Sebag-Montefiore tracked down Asché's daughter about 1999. USB was designed to allow peripherals to be connected without the need to plug expansion cards into the computer's ISA, EISA, or PCI bus, and to improve plug-and-play capabilities by allowing devices to be hot-swapped (connected or disconnected without powering down or rebooting the computer). Sixth, many writers have not done their research. USB cables do not need to be terminated. The account was claimed to have been written from the unpublished memoirs of an Australian cryptanalyst, but substantive parts of the published version appear to have been simply invented. Modern computers often have several host controllers, allowing a very large number of USB devices to be connected.

At least one incident is known of whole-cloth fabrication regarding British cryptanalytic progress on a particular World War II Japanese Navy cryptosystem. Not more than 127 devices, including the bus devices, may be connected to a single host controller. Fifth, several authors have had agendas which took precedence over accuracy in their reports. Additional USB hubs may be included in the chain, allowing branching into a tree structure, subject to a limit of 5 levels of branching per controller. Fourth, governments have chosen to keep secret or release information to serve their own purposes, not historical accuracy or completeness. A USB system has an asymmetric design, consisting of a host controller and multiple daisy-chained devices. In any case, none of them were originally written, nor made available later, with historical clarity in mind; considerable perspective is required to make reasonable use of them. .

Those not actually lost have taken decades to be released to the public, and some are, presumably, still to be released. Universal Serial Bus (USB) provides a serial bus standard for connecting devices, usually to computers such as PCs and the Apple Macintosh, but is also becoming commonplace on video game consoles such as Sony's PlayStation 2, Microsoft's Xbox 360, Nintendo's Revolution, and PDAs, and even devices like televisions and home stereo equipment. Third, documents have been 'lost' in secret archives. It appears that no work has been done on this package since 2003 so it may be abandoned. It requires someone with a considerable understanding of cryptanalysis, and of Enigma, to adequately comprehend -- or explain -- how either worked. The usb.windows package has a partial Windows implementation of a usb.core.Host object, bootstrapping support, and other classes leveraging Windows USB support. Second, the cryptanalytic work was tricky and quite technical. Java - The Mike Stahl started work on this combination in 2003.

Peter Calvocoressi's book, Top Secret Ultra, contains a sounder account of the episode. Java development is possible via JNI. The story about Churchill deliberately not interfering with a Luftwaffe bombing of Coventry which was known through Enigma decrypts is one such. Their COM interface allows for Delphi, C# and VB development. Several books have been published by those on the Ultra distribution side at Bletchley Park, but work there was seriously compartmentalised, making it difficult to credit some episodes when they are due only to such a source. General - USBIO has C++ drivers for USB communication on windows from C & C++. First, not all the authors were in a position to know. Java - No info is available on this combination.

General - Apple has this page on General Mac USB Development. This API is unfortunately limited to Linux. Java - The jUSB project provides a Free Software (and Open Source) Java API for USB, supporting applications using Java host-side software to drive USB devices. General - http://www.linux-usb.org/.

This is the current revision. USB On-The-Go Supplement 1.0a: Released in June 2003. USB On-The-Go Supplement 1.0: Released in December 2001. As an example, a computer's port could be incapable of USB 2.0's hi-speed fast transfer rates, but still claim USB 2.0 compliance (since it supports some of USB 2.0).

This makes the backwards compatibility explicit, but it becomes more difficult to determine a device's throughput without seeing the symbol. Added three speed distinction to this standard, allowing all devices to be USB 2.0 compliant even if they were previously considered only 1.1 or 1.0 compliant. USB 2.0: Revised in December 2002. This is the current revision.

The major feature of this standard was the addition of high-speed mode. USB 2.0: Released in April 2000. USB 1.1: Released in September 1998. USB 1.0: Released in January 1996.

USB 1.0 FDR: Released in November 1995, the same year that Apple adopted the IEEE 1394 standard known as FireWire. In a FireWire network, any capable node can control the network. A USB network relies on a single host at the top of the tree to control the network. A FireWire device can communicate with any other node at any time, subject to network conditions.

USB uses a "speak-when-spoken-to" protocol; peripherals cannot communicate with the host unless the host specifically requests communication. USB networks use a tiered-star topology, while FireWire networks use a repeater-based topology. Compliant devices must either fit within the size restrictions or support a compliant extension cable which does. This was done to avoid circumstances where a device complied with the connector specification but its large size blocked adjacent ports.

Unlike most other connector standards, the USB spec also defines limits to the size of a connecting device in the area around its plug. The USB standard specifies relatively low tolerances for compliant USB connectors, intending to minimize incompatibilities in connectors produced by different vendors (a goal that has been very successfully achieved). This type of enclosure also means that there is a (moderate) degree of protection from electromagnetic interference afforded to the USB signal while it travels through the mated connector pair (this is the only location when the otherwise twisted data pair must travel a distance in parallel). This sheath is typically connected to the system ground, allowing otherwise damaging static charges to be safely discharged by this route (rather than via delicate electronic components).

The connector construction always ensures that the external sheath on the plug contacts with its counterpart in the receptacle before the four connectors within are connected. The force needed to make or break a connection is modest, allowing connections to be made in awkward circumstances or by those with motor disabilities. USB cables and small USB devices are held in place by the gripping force from the receptacle (without the need for the screws, clips, or thumbturns other connectors require). A moderate insertion/removal force is specified.

RJ-45 cabling) gender-changers are never used, making it difficult to create a cyclic USB network. Unlike other communications systems (e.g. USB does not support cyclical networks, so the connectors from incompatible USB devices are themselves incompatible. The connectors enforce the directed topology of a USB network.

The connectors are particularly cheap to manufacture. However, it is not obvious at a glance to the inexperienced user which way round a connector goes, so it is often necessary to try both ways. Connectors cannot be plugged-in upside down, and it is clear from the appearance and kinesthetic sensation of making a connection when the plug and socket are correctly mated. It is difficult to incorrectly attach a USB connector.

The encasing sheath and the tough moulded plug body mean that a connector can be dropped, stepped upon, even crushed or struck, all without damage; a considerable degree of force is needed to significantly damage a USB connector. As a result USB connectors can safely be handled, inserted, and removed, even by a small child. The electrical contacts in a USB connector are protected by an adjacent plastic tongue, and the entire connecting assembly is further protected by an enclosing metal sheath. Many previous connector designs were fragile, with pins or other delicate components prone to bending or breaking, even with the application of only very modest force.

The connectors are designed to be robust. A Hi-Speed rate of 480 Mbit/s (57 MiB/s). All USB Hubs support Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices.

Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. A Full Speed rate of 12 Mbit/s (1.4 MiB/s). A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice and joysticks. file transfers.

bulk transfers - large sporadic transfers using all remaining available bandwidth (but with no guarantees on bandwidth or latency), e.g. pointing devices and keyboards. interrupt transfers - devices that need guaranteed quick responses (bounded latency), e.g. realtime audio or video.

isochronous transfers - at some guaranteed speed (often but not necessarily as fast as possible) but with possible data loss, e.g. by the bus control pipe number 0. control transfers - typically used for short, simple commands to the device, and a status response, used e.g.