1. Password Cracking With Rainbow Tables
Spencer Dawson

2. Summary What are rainbow tables? What are the advantages/disadvantages
A time and memory tradeoff in password cracking.
A piecewise approach to one-way hashes
What are the advantages/disadvantages
Best uses
Limitations
How to use rainbow tables.

3. What are rainbow tables?
A rainbow table is a lookup table offering a time-memory tradeoff used in recovering the plaintext password from a password hash generated by a hash function
Approach invented by Martin Hellman
The concept behind rainbow tables is simple
Make one-way hash functions two way by making a list of outputs for all possible inputs up to a character limit

4. What are the limitations?
Rainbow Tables are Large
A rainbow table set for windows NTHASH exactly 8 characters including only 0-10, a-z, A-Z, and the symbols !* is 134.6GB
9+ character rainbow tables can take up terabytes of space.
Generating rainbow tables requires more time than a brute force attack
Always “worst case” time complexity.
Requires access to the password hash
Salting passwords can make the approach unfeasable

5. Hash Table Advantages
Rainbow Tables are built once, and used many times
Fast
Password lookups become a table search problem
The brute force work is pre-computed
Perfect for cracking weak hashes
Windows LM hashes of 14 characters or less can be cracked with trivial effort
Any non salting password hash can be cracked easily

6. Examples
Rainbow table cracking online

7. QUESTIONS?