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Thursday, October 4, 2018

How to crack wifi password | Dictionary attack - YouTube
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In cryptanalysis and computer security, a dictionary attack is a type of brute force attack technique for defeating a cipher or authentication mechanism by trying to determine its decryption key or passphrase by trying hundreds or sometimes millions of likely possibilities, such as words in a dictionary.


Video Dictionary attack



Technique

A dictionary attack is based on trying all the strings in a pre-arranged listing, typically derived from a list of words such as in a dictionary (hence the phrase dictionary attack). In contrast to a brute force attack, where a large proportion of the key space is searched systematically, a dictionary attack tries only those possibilities which are deemed most likely to succeed. Dictionary attacks often succeed because many people have a tendency to choose short passwords that are ordinary words or common passwords, or simple variants obtained, for example, by appending a digit or punctuation character. Dictionary attacks are relatively easy to defeat, e.g. by using a passphrase or otherwise choosing a password that is not a simple variant of a word found in any dictionary or listing of commonly used passwords.


Maps Dictionary attack



Pre-computed dictionary attack/Rainbow table attack

It is possible to achieve a time-space tradeoff by pre-computing a list of hashes of dictionary words, and storing these in a database using the hash as the key. This requires a considerable amount of preparation time, but allows the actual attack to be executed faster. The storage requirements for the pre-computed tables were once a major cost, but are less of an issue today because of the low cost of disk storage. Pre-computed dictionary attacks are particularly effective when a large number of passwords are to be cracked. The pre-computed dictionary need be generated only once, and when it is completed, password hashes can be looked up almost instantly at any time to find the corresponding password. A more refined approach involves the use of rainbow tables, which reduce storage requirements at the cost of slightly longer lookup-times. See LM hash for an example of an authentication system compromised by such an attack.

Pre-computed dictionary attacks, or "rainbow table attacks", can be thwarted by the use of salt, a technique that forces the hash dictionary to be recomputed for each password sought, making precomputation infeasible, provided the number of possible salt values is large enough.


Dictionary Attack Image
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Dictionary attack software

  • Cain and Abel
  • Crack
  • Aircrack-ng
  • John the Ripper
  • L0phtCrack
  • Metasploit Project
  • Ophcrack

what is brute force attack & dictionary attack ? |TECH SETTAI ...
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See also

  • E-mail address harvesting
  • Key derivation function
  • Key stretching
  • Password cracking
  • Password strength

How to do a Dictionary attack on Remote Desktop Protocol - YouTube
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References


Hydra mysql dictionary attack - YouTube
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External links

  • RFC 2828 - Internet Security Glossary
  • RFC 4949 - Internet Security Glossary, Version 2
  • RSA BSAFE Crypto-C Glossary
  • US Secret Service use a distributed dictionary attack on suspect's password protecting encryption keys
  • Testing for Brute Force (OWASP-AT-004)

Source of article : Wikipedia