Leetspeak Strategy

The Leetspeak strategy tests an AI system's ability to resist encoded inputs that might bypass security controls by replacing letters with visually similar numbers or symbols (e.g., a→4, e→3, t→7), leveraging the fact that models frequently encounter this internet-native text transformation during pretraining but safety training often fails to catch these character substitutions.

Implementation

Use it in your promptfooconfig.yaml:

strategies:
  - leetspeak

How It Works

Leetspeak transforms text by:

1. Taking the original text from your test case
2. Replacing certain letters with visually similar numbers or symbols
3. Creating a variant that humans can generally read but may bypass automated filters
4. Testing whether the model processes the leetspeak text differently than plain text

Example Scenarios

The strategy substitutes a → 4, e → 3, i/l → 1, o → 0, s → 5, and t → 7:

The strategy helps identify:

• Model's handling of informal text transformations
• Safety training gaps around common internet text patterns
• Potential for natural-looking obfuscation

Related Concepts

• Base64 Encoding - More formal encoding scheme
• ROT13 Encoding - More systematic substitution
• Prompt Injection - Can be combined with Leetspeak
• Red Team Strategies - Full strategy catalog