MDC

MDC may refer to:

MDC-2

In cryptography, MDC-2 (Modification Detection Code 2, sometimes called Meyer-Schilling) is a cryptographic hash function. MDC-2 is a hash function based on a block cipher with a proof of security in the ideal-cipher model. The length of the output hash depends on the underlying block cipher used.

Algorithm

For a given message to hash and a given block cipher encryption function , the MDC-2 algorithm proceeds as follows. Let be the block length, two different constants of size . If where each has size , then the hash of the message is given by:

for to :

• 
• 
• 
• 
• 
• 

return

MDC-2DES hashes

When MDC-2 uses the DES block cipher, the 128-bit (16-byte) MDC-2 hashes are typically represented as 32-digit hexadecimal numbers. The following demonstrates a 43-byte ASCII input and the corresponding MDC-2 hash:

Even a small change in the message will (with probability) result in a completely different hash, e.g. changing d to c:

The hash of the zero-length string is:

Patent issues

MDC-2 was covered by U.S. Patent 4,908,861, issued on March 13, 1990 but filed by IBM on August 28, 1987.
For this reason, support for MDC-2 has been disabled in OpenSSL on most Linux distributions and is not implemented by many other cryptographic libraries.

One-way compression function

In cryptography, a one-way compression function is a function that transforms two fixed-length inputs into a fixed-length output. The transformation is "one-way", meaning that it is difficult given a particular output to compute inputs which compress to that output. One-way compression functions are not related to data compression, which by definition can be inverted exactly (lossless compression) or approximately (lossy compression) to the original data.

One-way compression functions are for instance used in the Merkle–Damgård construction inside cryptographic hash functions.

One-way compression functions are often built from block ciphers. Some methods to turn any normal block cipher into a one-way compression function are Davies–Meyer, Matyas–Meyer–Oseas, Miyaguchi–Preneel (single-block-length compression functions) and MDC-2/Meyer–Schilling, MDC-4, Hirose (double-block-length compression functions). These methods are described in detail further down. (MDC-2 is also the name of a hash function patented by IBM.)

Sociobiological theories of rape

Sociobiological theories of rape explores how evolutionary adaptation influences the psychology of rapists. Such theories are highly controversial, as traditional theories typically do not consider rape to be a behavioral adaptation. Some object to such theories on ethical, religious, political, or scientific grounds. Others argue that a correct knowledge of the causes of rape is necessary to develop effective preventive measures.

A Natural History of Rape

The idea that rape evolved under some circumstances as a genetically advantageous behavioral adaptation was popularized by biologist Randy Thornhill and anthropologist Craig T. Palmer in their 2000 book A Natural History of Rape: Biological Bases of Sexual Coercion.

Animal coercive sex

It has been noted that behavior resembling rape in humans is observed in the animal kingdom, including ducks and geese, bottlenose dolphins, and chimpanzees. Indeed in orangutans, close human relatives, copulations of this nature may account for up to half of all observed matings. Such behaviours, referred to as ‘forced copulations’, involve an animal being approached and sexually penetrated as it struggles or attempts to escape. These observations of forced sex among animals are not controversial. What is controversial is the interpretation of these observations and the extension of theories based on them to humans. “Thornhill introduces this theory by describing the sexual behavior of scorpionflies. In which the male may gain sex from the female either by presenting a gift of food during courtship or without a nuptial offering, in which case force is necessary to restrain her.”

Rape (film)

Rape (Norwegian: Voldtekt) is a 1971 false document Norwegian film by renowned female director Anja Breien. The film deals with a young man who is mistakenly accused of one rape and one attempted rape and how he is being processed by the judicial system. The film is shot in black and white and is divided into sections corresponding to the respective sections of Norwegian trial law which the accused encounters.

External links

Rapeseed

Rapeseed (Brassica napus), also known as rape,oilseed rape,rapa, rappi, rapaseed (and, in the case of one particular group of cultivars, canola), is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), consumed in China (油菜: Mandarin Pinyin yóucài; Cantonese:yau choy) and Southern Africa as a vegetable. The name derives from the Latin for turnip, rāpa or rāpum, and is first recorded in English at the end of the 14th century. Older writers usually distinguished the turnip and rape by the adjectives 'round' and 'long' (-'rooted'), respectively.Rutabagas, Brassica napobrassica, are sometimes considered a variety of B. napus. Some botanists also include the closely related B. campestris within B. napus.

B. napus is cultivated mainly for its oil-rich seed, the third-largest source of vegetable oil in the world.

Common names

Rapeseed is known by many common names in the English language. Some names have only been applied to certain subspecies (subsp.), forms (f.), or varieties (var.) of B. napus. B. napus = B. napus subsp. napus = B. napus subsp. napus f. napus.

Crime

In ordinary language, the term crime denotes an unlawful act punishable by a state. The term "crime" does not, in modern criminal law, have any simple and universally accepted definition, though statutory definitions have been provided for certain purposes. The most popular view is that crime is a category created by law; in other words, something is a crime if declared as such by the relevant and applicable law. One proposed definition is that a crime or offence (or criminal offence) is an act harmful not only to some individual or individuals but also to a community, society or the state ("a public wrong"). Such acts are forbidden and punishable by law.

The notion that acts such as murder, rape and theft are to be prohibited exists worldwide. What precisely is a criminal offence is defined by criminal law of each country. While many have a catalogue of crimes called the criminal code, in some common law countries no such comprehensive statute exists.

The state (government) has the power to severely restrict one's liberty for committing a crime. In modern societies, there are procedures to which investigations and trials must adhere. If found guilty, an offender may be sentenced to a form of reparation such as a community sentence, or, depending on the nature of their offence, to undergo imprisonment, life imprisonment or, in some jurisdictions, execution.