BSidesNYC CTFd Writeup - BASEic Encoding

Step 1: Identifying the Encoding

The primary clue is the string itself. It contains a vast range of characters that fall outside the standard ASCII or even common UTF-8 text, including characters from various scripts and symbols (e.g., CJK Unified Ideographs, Egyptian Hieroglyphs).

This is a classic indicator of Base65536 encoding. Unlike more common encodings like Base64, which uses a 64-character set, Base65536 utilizes a massive range of 65,536 Unicode characters to represent binary data more compactly. The challenge's title, "BASEic Encoding," and the hint "just BASEs hehe" directly point to a number base system, and this is a particularly large one.

Step 2: Decoding the String

Once Base65536 is identified as the encoding scheme, you can decode the string using several methods.

For CTF challenges, online tools are often the quickest way to test a hypothesis.

1. Navigate to a Base65536 decoder. A functional one is better-converter.com.
2. Input the string. Copy the challenge string ꍦ鱡𓍻普散桤鵟ꌰ橤𓅟頳桲𓄷敟鑦鵴樱靟樴𠌳 into the input field.
3. Decode. Execute the decoding function on the website.

The tool will process the string and output the decoded flag.

Result:

flag{un1c0d3_h0ld5_s3cr37s_0f_th15_b453}