SUMMARY / RELATED TOPICS

Checksum

A checksum is a small-sized datum derived from a block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are used to verify data integrity but are not relied upon to verify data authenticity; the procedure which generates this checksum is called a checksum checksum algorithm. Depending on its design goals, a good checksum algorithm will output a different value for small changes made to the input; this is true of cryptographic hash functions, which may be used to detect many data corruption errors and verify overall data integrity. Checksum functions are related to hash functions, randomization functions, cryptographic hash functions. However, each of those concepts has different applications and therefore different design goals. For instance, a function returning the start of a string can provide a hash appropriate for some applications but will never be a suitable checksum. Checksums are used as cryptographic primitives in larger authentication algorithms.

For cryptographic systems with these two specific design goals, see HMAC. Check digits and parity bits are special cases of checksums, appropriate for small blocks of data; some error-correcting codes are based on special checksums which not only detect common errors but allow the original data to be recovered in certain cases. The simplest checksum algorithm is the so-called longitudinal parity check, which breaks the data into "words" with a fixed number n of bits, computes the exclusive or of all those words; the result is appended to the message as an extra word. To check the integrity of a message, the receiver computes the exclusive or of all its words, including the checksum. With this checksum, any transmission error which flips a single bit of the message, or an odd number of bits, will be detected as an incorrect checksum. However, an error which affects two bits will not be detected if those bits lie at the same position in two distinct words. Swapping of two or more words will not be detected.

If the affected bits are independently chosen at random, the probability of a two-bit error being undetected is 1/n. A variant of the previous algorithm is to add all the "words" as unsigned binary numbers, discarding any overflow bits, append the two's complement of the total as the checksum. To validate a message, the receiver adds all the words including the checksum; this variant too detects any single-bit error, but the promodular sum is used in SAE J1708. The simple checksums described above fail to detect some common errors which affect many bits at once, such as changing the order of data words, or inserting or deleting words with all bits set to zero; the checksum algorithms most used in practice, such as Fletcher's checksum, Adler-32, cyclic redundancy checks, address these weaknesses by considering not only the value of each word but its position in the sequence. This feature increases the cost of computing the checksum; the idea of fuzzy checksum was developed for detection of email spam by building up co-operative databases from multiple ISPs of email suspected to be spam.

The content of such spam may vary in its details, which would render normal checksumming ineffective. By contrast a "fuzzy checksum" reduces the body text to its characteristic minimum generates a checksum in the usual manner; this increases the chances of different spam emails producing the same checksum. The ISP spam detection software, such as SpamAssassin, of co-operating ISPs submits checksums of all emails to the centralised service such as DCC. If the count of a submitted fuzzy checksum exceeds a certain threshold, the database notes that this indicates spam. ISP service users generate a fuzzy checksum on each of their emails and request the service for a spam likelihood. A message, m bits long can be viewed as a corner of the m-dimensional hypercube; the effect of a checksum algorithm that yields an n-bit checksum is to map each m-bit message to a corner of a larger hypercube, with dimension m + n. The 2m+n corners of this hypercube represent all possible received messages; the valid received messages comprise a smaller set, with only 2m corners.

A single-bit transmission error corresponds to a displacement from a valid corner to one of the m adjacent corners. An error which affects k bits moves the message to a corner, k steps removed from its correct corner; the goal of a good checksum algorithm is to spread the valid corners as far from each other as possible, so as to increase the likelihood "typical" transmission errors will end up in an invalid corner. General topic Algorithm Check digit Damm algorithm Data rot File verification Fletcher's checksum Frame check sequence cksum md5sum sha1sum Parchive sum SYSV checksum BSD checksum xxHashError correction Hamming code IPv4 header checksumHash functions List of hash functions Luhn algorithm Parity bit Rolling checksum Verhoeff algorithm ZFS — a file system which performs automatic file integrity checking using checksumsRelated concepts Isopsephy Gematria Additive Checksums theory from

Yamagata Airport

Yamagata Airport is a 2nd-class airport in Higashine, Japan. The airport is 23 kilometres north of the city of Yamagata. Kamiyama Training Airfield was opened by the Imperial Japanese Navy in World War II, it was used by the United States military after the war and by the Japanese Self-Defense Force as a training facility. In June 1964, it was turned over to civilian control as “Jinmachi Airport”, a third-class regional airport, it was renamed Yamagata Airport in 1965. A helicopter detachment from the JGSDF 6th Division has been based at the airport since 1969; the runway was extended to 1500 meters in 1972, the airport was re-designated as Class-II in 1979. The runway was further extended to 2000 meters in 1981 and a new terminal building completed in 1984. Scheduled services began in 1964, with All Nippon Airways operating Fokker F.27 service to Tokyo. The service was upgraded to YS-11s in 1972 and to Boeing 737s in 1976. By 1985 ANA offered five daily flights to Haneda, one of, operated by a widebody Boeing 767.

Japan Air System began service to Osaka and Sapporo in 1979. International charter service commenced in 1981, the airport hosted long-haul charters to countries such as Finland, New Zealand and Mexico; the number of passengers using the airport peaked in 1991 and declined precipitously on the Tokyo route, due to the completion of the Yamagata Shinkansen in 1992. The Tokyo route saw 470,618 passengers in 1991 but was down to 43,447 passengers in 2002. All Nippon Airways suspended the Tokyo service and withdrew from the airport in 2002, with JAS resuming the route as a single daily MD-87 service in 2003. JAS operated an Osaka service from 1995 to 2002, a Fukuoka service from 2006 to 2008, while Nakanihon Airlines operated a summer seasonal Hakodate service from 1998 to 2001; the airport is served by JAL and FDA using an Embraer 170 to Tokyo and Nagoya. During the aftermath of the 2011 Tohoku earthquake and tsunami, American troops used Yamagata Airport as a base for transporting fuel and materials to the disaster areas.

According to the Ministry of Defense, this was the first time that the U. S. military had used a private airport in Japan for anything other than emergency landings. The airport has a two-story terminal with a rooftop observation deck; the airport has bus service to Yamagata Station timed to coincide with flight schedules to and from Tokyo and Nagoya. Sakurambo-Higashine Station is seven minutes by car but is not connected to the airport by scheduled transportation. Home page Yamagata Prefectural Government Current weather for RJSC at NOAA/NWS Accident history for GAJ at Aviation Safety Network

Roselyn Bakery

Roselyn Bakery was a major bakery chain that distributed products from an Indianapolis central baking facility from 1943 to 1999. The bakery chain, which consisted of 40 locations in and around central Indiana, was known for its popular treats such as their Sweetheart Coffee Cake, Zebra Square Brownies and Blackout Cake. In July 1999, the factory was abruptly shut down by the Indiana State Department of Health for repeated/severe code violations; the entire chain was dissolved soon after. Despite the closure being publicized by the local media, the popularity of Roselyn Bakeries' products did not wane. In 2000, the Kroger grocery chain sold a limited-edition cookbook of the bakery's recipes. At the same time, a bakery in Chicago was contracted to produce a limited number of bakery products for distribution at local supermarkets. In 2005, the Dias family, along with another partner, purchased Roselyn Recipe and the assets of Roselyn Bakery from the Clark family. Two bakeries were established, one in St. Louis and the other in Indianapolis, to continue the production and distribution of these products.

Roselyn Recipe treats can be found and purchased in Kroger stores all over central Indiana. A brief history of Roselyn Bakeries at historicindianapolis.com