> For the complete documentation index, see [llms.txt](https://sarpers-organization.gitbook.io/ctftricks/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sarpers-organization.gitbook.io/ctftricks/_chapter-intro-3/obfuscation/multi-stage-decoding/trick-0321.md).

# Combine & Decode Multi-Part Base64 (Crests)

***

In some challenges, encoded data (like Base64) might be split across multiple locations (e.g., different web pages, files, comments). The trick is to identify these fragments, often by recognizing they are part of the same encoding scheme, concatenate them in the correct order, and then decode the combined string. The process involves identifying the fragments, combining them, and then decoding the result, essentially needing to join two base64 strings and then decode them.

For example, finding fragments like `RlRQIHVzZXI6IG` and `h1bnRlciwgRlRQIHBh` from different sources (like 'crests' in the input notes), identifying their correct sequence, and combining them to form the full encoded string:

```
RlRQIHVzZXI6IGh1bnRlciwgRlRQIHBhc3M6IHlvdV9jYW4+aGlkZV9mb3JldmVy==
```

Decoding the combined string using Base64 then reveals the hidden information (e.g., credentials like `FTP user: hunter, FTP pass: you_can't_hide_forever`).