navi-sanitize¶

Deterministic sanitization for untrusted text. Strips invisible and control characters, normalizes compatibility forms and replaces a curated set of homoglyphs before your code compares, stores, logs or renders the text. Python 3.12+, standard library only, no ML.

Get Started API Reference

See the invisible¶

from navi_sanitize import clean

evil = "system\u200b\u200cprompt"  # looks like "systemprompt" but has 2 hidden chars
len(evil)    # 14
clean(evil)  # 'systemprompt'

What it does¶

• A fixed pipeline --- null bytes, 492 invisible/format/control characters, NFKC normalization, 66 homoglyph replacements and re-normalization, then an optional escaper you choose
• Deterministic --- the same input always gives the same output; property and fuzz tests check that clean() is idempotent
• No dependencies --- standard library only
• Nested data --- walk() sanitizes every string in dicts and lists, keys included, into new containers
• Content-free logging --- warnings report counts ("Stripped 3 invisible character(s)"), never input text
• Opt-in helpers --- decode_evasion() for nested URL/HTML/hex encodings, detect_scripts() / is_mixed_script() for mixed-script signals; none run automatically

What it does not do¶

It changes some legitimate text, its homoglyph map is deliberately small, and its escapers are narrow helpers rather than sandboxes. It does not replace HTML escaping, parameterized SQL, template autoescaping, path confinement or prompt-injection defenses. The threat model lists the limits.

Quick start¶

pip install navi-sanitize

from navi_sanitize import clean

clean("Неllo Wоrld")      # 'Hello World' (Cyrillic Н and о replaced)
clean("price:\u200b 0")   # 'price: 0' (zero-width space stripped)
clean("file\x00.txt")     # 'file.txt' (null byte removed)

Documentation¶

Links¶

• GitHub Repository
• Issue Tracker
• PyPI