Module perplexity 

Character-class bigram perplexity filter for detecting adversarial suffixes.

Adversarial prompt injection attacks often append high-perplexity suffix strings that look nothing like natural language. This filter scores the suffix window of incoming prompts using character-class bigram frequencies and blocks prompts that exceed the perplexity threshold.

Enums

PerplexityResult

Result of perplexity filter analysis.

Functions

analyze_suffix

Analyze the suffix window of a prompt for adversarial content.

bigram_perplexity

Compute character-class bigram perplexity for a string.

symbol_ratio

Compute the ratio of symbol/punctuation characters in the text.