information entropy

information entropy
A measure of the uncertainty associated with a random variable ; a measure of the average information content one is missing when one does not know the value of the random variable ; usually in units such as bits.

A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. — BSD General Commands Manual : ssh-keygen(1), October 2, 2010.


Wikipedia foundation.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • Information entropy — Während ordinale Insolvenzprognosen lediglich eine Reihung von Unternehmen entsprechend den erwarteten Ausfallwahrscheinlichkeiten vornehmen, ordnen kardinale Insolvenzprognosen jedem Unternehmen explizit eine Ausfallwahrscheinlichkeit zu.[1]… …   Deutsch Wikipedia

  • Entropy (arrow of time) — Entropy is the only quantity in the physical sciences that picks a particular direction for time, sometimes called an arrow of time. As one goes forward in time, the second law of thermodynamics says that the entropy of an isolated system can… …   Wikipedia

  • Information — as a concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control, data, form, instruction, knowledge, meaning,… …   Wikipedia

  • Entropy — This article is about entropy in thermodynamics. For entropy in information theory, see Entropy (information theory). For a comparison of entropy in information theory with entropy in thermodynamics, see Entropy in thermodynamics and information… …   Wikipedia

  • Information theory — Not to be confused with Information science. Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental… …   Wikipedia

  • Entropy (information theory) — In information theory, entropy is a measure of the uncertainty associated with a random variable. The term by itself in this context usually refers to the Shannon entropy, which quantifies, in the sense of an expected value, the information… …   Wikipedia

  • Entropy in thermodynamics and information theory — There are close parallels between the mathematical expressions for the thermodynamic entropy, usually denoted by S , of a physical system in the statistical thermodynamics established by Ludwig Boltzmann and J. Willard Gibbs in the 1870s; and the …   Wikipedia

  • Entropy (general concept) — In many branches of science, entropy refers to a certain measure of the disorder of a system. Entropy is particularly notable as it has a broad, common definition that is shared across physics, mathematics and information science. Although the… …   Wikipedia

  • Information gain in decision trees — In information theory and machine learning, information gain is an alternative synonym for Kullback–Leibler divergence . In particular, the information gain about a random variable X obtained from an observation that a random variable A takes the …   Wikipedia

  • Entropy (anonymous data store) — Infobox Software name = Entropy caption = collapsible = author = developer = released = latest release version = latest release date = 2004 latest preview version = latest preview date = frequently updated = programming language = operating… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”