Brute force (also known as brute force cracking) is a trial and error method used by application programs to decode encrypted data such as passwords or Data Encryption Standard (DES) keys, through exhaustive effort (using brute force) rather than employing intellectual strategies. Just as a criminal might break into, or "crack" a safe by trying many possible combinations, a brute force cracking application proceeds through all possible combinations of legal characters in sequence. Brute force is considered to be an infallible, although time-consuming, approach.
Crackers are sometimes used in an organization to test network security, although their more common use is for malicious attacks. Some variations, such as L0phtcrack from L0pht Heavy Industries, start by making assumptions, based on knowledge of common or organization-centered practices and then apply brute force to crack the rest of the data. L0phtcrack uses brute force to crack Windows NT passwords from a workstation. PC Magazine reported that a system administrator who used the program from a Windows 95 terminal with no administrative privileges, was able to uncover 85 percent of office passwords within twenty minutes.