CPU vs GPU

When it comes to password cracking, both CPUs and GPUs have their own advantages and are suited to different tools and scenarios. Here's a comparison to help you understand which to use and when.

CPU Cracking

Advantages:

1. Flexibility: CPUs can handle a wider variety of tasks and are better suited for algorithms that involve complex, sequential processing.

2. Compatibility: Most password cracking tools can run on a CPU, and many are optimized for CPU usage.

3. Cost: CPUs are generally cheaper to implement for smaller-scale tasks.

Tools Optimized for CPU:

1. John the Ripper:

   • Versatile and supports numerous hashing algorithms.

   • Great for single-threaded and small-scale parallel processing tasks.

   • Suitable for incremental mode and complex rule-based attacks.

   • Example:

     john --wordlist=wordlist.txt hashes.txt

2. Hydra:

   • Often used for network service brute force attacks.

   • Supports many protocols and services.

   • Example:

     hydra -l admin -P passwords.txt ssh://target

Use Cases:

• Environments without powerful GPUs.

• Tasks involving complex logic or rules.

• Situations where the cost of GPU hardware isn't justified.

GPU Cracking

Advantages:

1. Speed: GPUs can perform many calculations simultaneously, making them extremely efficient for parallelizable tasks.

2. Efficiency: They are much faster than CPUs for tasks like hashing and encryption, which involve repetitive calculations.

3. Scalability: You can use multiple GPUs to scale up your cracking efforts.

Tools Optimized for GPU:

1. Hashcat:

   • One of the fastest password recovery tools.

   • Leverages the power of GPUs for massive parallel processing.

   • Supports various attack modes, including dictionary, brute force, combinator, mask, and hybrid.

   • Example:

     hashcat -a 0 -m 0 hashes.txt wordlist.txt

2. oclHashcat (an older version of Hashcat):

   • Specialized for GPUs, though now merged into Hashcat.

   • Used for complex hashing algorithms.

Use Cases:

• Cracking large lists of hashes.

• Tasks that require high-speed brute force or dictionary attacks.

• Environments equipped with powerful GPU hardware.

Comparison Summary

Feature	CPU	GPU
Speed	Slower, but good for complex tasks	Much faster for repetitive tasks
Flexibility	High	Medium
Cost	Lower for small-scale tasks	Higher due to hardware costs
Tool Examples	John the Ripper, Hydra	Hashcat, oclHashcat
Best For	Complex logic, small-scale tasks	High-speed, large-scale cracking

Practical Examples

John the Ripper (CPU):

john --wordlist=wordlist.txt hashes.txt

Hashcat (GPU):

hashcat -a 0 -m 0 hashes.txt wordlist.txt

Conclusion

• Use CPU for tasks involving complex rules, logic, or where cost is a concern.

• Use GPU for high-speed, large-scale password cracking, especially when dealing with large hash lists or requiring massive parallel processing power.

Choosing the right tool and hardware depends on your specific requirements, resources, and the nature of the task at hand.

When working with a GPU, ensure the correct drivers are installed. Prefer a bare-metal installation over a VM, especially for NVIDIA on Windows.