Exactly what is A Brute force attack

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In cryptography, a brute-force attack, or exhaustive key search, is a cryptanalytic attack that may, in theory, be used against any encrypted data (except for information encrypted in an information-theoretically safe manner). Such an attack may be used when it isn't feasible to take advantage of other weaknesses in an encryption method (if any exist) that would make the task easier. It consists of systematically checking all possible keys or passwords until the correct one is discovered. In the worst case, this would involve traversing the entire search space.

When password guessing, this technique is very fast when used to check all brief passwords, but for longer passwords other techniques such as the dictionary attack are used because of the time a brute-force search requires.

When key guessing, the key length used in the cipher determines the sensible feasibility of performing a brute-force attack, with longer keys exponentially more hard to crack than shorter ones. A cipher having a key length of N bits may be broken inside a worst-case time proportional to 2N and an average time of half that.

Brute-force attacks can be made less effective by obfuscating the data to become encoded, something that makes it more tough for an attacker to recognize when he/she has cracked the code. One of the measures of the strength of an encryption method is how lengthy it would theoretically take an attacker to mount a successful brute-force attack against it.

Brute-force attacks are an application of brute-force search, the general problem-solving technique of enumerating all candidates and checking each one.

The term "brute-force" is not the only term to name such a kind of attack. It could also be known as "bruteforce", "brute force" and just "brute" (that is common in names of programs that carry out brute-force attacks).

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