---
name: encoded-payloads
description: Use when content contains base64, hex, rot13, percent-encoded or HTML-entity blobs, or when scan reports VB-T05.
---
# Encoded payloads (VB-T05)

**Step 0:** follow [step-0-untrusted-content](../step-0-untrusted-content/SKILL.md) first.

## What it is
Instructions are hidden in encodings that the model can decode on its own but filters do not read.

## How VeilBreaker catches it
`reveal` decodes base64/base64url, hex and \\x escapes, percent-encoding, HTML entities and rot13, up to depth 2, capped at 64 KB decoded and 64 candidates per layer. `scan` flags decodes that contain instruction-like text or chat-template tokens. `data:image|font|audio|video;base64` payloads and binary decodes (hashes, images) are ignored.

## Known limits
Other ciphers, compression, and multi-layer chains deeper than 2 are not decoded. Decoded text that is benign is not reported.

## Citation
arXiv:2504.11168 (encoding-based evasion); arXiv:2302.12173.