rcrack

rcrack [options] hash(es)

-h
    Specifies the hash algorithm to be used (e.g., md5, sha1, lm, ntlm).

-l
    Specifies which rainbow table to use by index.

-t
    Specifies the filename of the rainbow table to use.


    The hash value(s) to crack. Multiple hashes can be specified separated by spaces.

-q
    Quiet mode. Suppresses verbose output.

-b
    Brute-force search when rainbow table lookup fails.

-a
    Crack all hashes in the input file.

-i
    Specifies an input file containing a list of hashes to crack.

-o
    Specifies the output file to write the cracked passwords.

-g
    Guess plaintext from hash when rainbow table lookup fails.

rcrack is a command-line tool part of the RainbowCrack suite, designed for recovering passwords using pre-computed rainbow tables. It efficiently searches these tables to find the plaintext password that corresponds to a given hash.

Rainbow tables are pre-calculated hash chains that significantly speed up the password cracking process compared to brute-force or dictionary attacks, especially for common password hashing algorithms like MD5, SHA1, and NTLM. rcrack takes a hash as input and searches through the specified rainbow tables. If a match is found, rcrack outputs the corresponding plaintext password.

It supports various table formats and can be configured to search multiple tables simultaneously, enhancing the speed and effectiveness of the cracking process. This tool is invaluable for security professionals and penetration testers needing to assess password security by recovering passwords from captured hashes. However, responsible use and ethical considerations are paramount when employing this tool.

Rainbow tables can be very large, requiring significant storage space.
The effectiveness of rcrack depends on the coverage of the rainbow tables used and the complexity of the passwords being cracked.
Using this tool against systems without authorization is illegal and unethical.

Rainbow tables must be pre-computed using the 'rtgen' tool before they can be used with rcrack. The 'rtgen' tool allows users to create rainbow tables based on specified character sets, password lengths, and hash algorithms.

The rtsort tool can be used to sort rainbow tables for optimal performance. Sorted tables allows rcrack to find better candidates.

rcrack is part of the RainbowCrack suite, a project initiated to demonstrate the effectiveness of rainbow tables for password cracking.

The RainbowCrack suite was created by Zhenhua Wang in 2005. It has seen continuous development and refinement over the years, with updates focusing on performance optimization and support for various hash algorithms.

Its widespread adoption among security professionals and penetration testers highlights its utility in assessing password security and identifying weak passwords.

rainbowcrack(1)