How are hashes cracked?

Sometimes a hacker may choose to crack the hash instead of passing it. There are many great tools available to crack password hashes such as rainbowcrack. This tool uses rainbow tables to crack hashes. Rainbow tables are used for longer passwords. The way they work is by using hash and reduction functions. Hash functions map plaintext to hashes and reduction functions map hashes to plaintext. These functions create chains of hash values mapped to plaintext. The chain starts with a specific plaintext and ends with a specific hash. The plaintext at the beginning of the chain is hashed by the hash function and then reduced by the reduction function to create a different plaintext. This pattern can repeat many times generating millions of hashes from a single plaintext and a single hash. Creating rainbow tables can take hours to complete depending on how you want to configure your rainbow table...