What exactly is A Brute force attack

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In cryptography, a brute-force attack, or exhaustive key search, is a cryptanalytic attack that can, 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 is not possible to take benefit of other weaknesses in an encryption system (if any exist) that would make the job simpler. It consists of systematically checking all possible keys or passwords until the right one is discovered. In the worst case, this would involve traversing the entire search space.

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

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 difficult to crack than shorter ones. A cipher with a key length of N bits can be broken inside a worst-case time proportional to 2N and an average time of half that.

Brute-force attacks can be made much less efficient by obfuscating the data to be encoded, something that tends to make it more difficult 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 common problem-solving technique of enumerating all candidates and checking each one.

The term "brute-force" isn't the only term to name such a type of attack. It can also be called "bruteforce", "brute force" and just "brute" (that's typical in names of programs that perform brute-force attacks).

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