Rating: 3.0
# Eggs Over Easy — Writeup
## Description
In this challenge, I was given a file that appeared to contain no visible text at first glance. After closer inspection, I noticed that the file consisted only of two types of whitespace characters:
- `space`
- `tab`
Since there were only two possible symbols, this strongly suggested binary encoding.
I mapped them as follows:
- `space = 0`
- `tab = 1`
## Solution
First, I converted the full sequence of spaces and tabs into a bitstring using that mapping.
Then I split the bitstring into groups of 8 bits and converted each group into its ASCII representation.
This produced the following intermediate result:
```text
ff35 ff24 ff23 ff34 46 ff5b ff22 ff14 ff43 ff4f ff4e ff5d
```
This was not the final flag yet, but it clearly looked like a sequence of hexadecimal Unicode code points.
Most of the values started with `FF`, which is commonly associated with fullwidth Unicode characters.
After converting each hexadecimal value into its corresponding Unicode character, I obtained:
```text
ＵＤＣＴF｛Ｂ４ｃｏｎ｝
```
At this point, it became clear that the text was written mostly with fullwidth Unicode symbols instead of standard ASCII characters.
By applying Unicode normalization with `NFKC`, those fullwidth symbols were converted into normal ASCII text.
The final decoded flag was:
```text
UDCTF{B4con}
```
## Hint Analysis
The challenge hint said:
> If you know what goes well with eggs, this will be over easily...
This points to **bacon**, which matches the last part of the decoded flag and confirms that the solution is correct.
## Final Flag
```text
UDCTF{B4con}
```
## Solver Script
```python
from pathlib import Path
import unicodedata
filename = "txt (7)"
data = Path(filename).read_text()
# space = 0, tab = 1
bits = ''.join('0' if ch == ' ' else '1' for ch in data)
# Convert every 8 bits into ASCII
hex_text = ''.join(chr(int(bits[i:i+8], 2)) for i in range(0, len(bits), 8))
# Split hex tokens
tokens = hex_text.split()
# Convert hex -> Unicode characters
decoded = ''.join(chr(int(token, 16)) for token in tokens)
# Normalize fullwidth Unicode characters into normal ASCII
flag = unicodedata.normalize("NFKC", decoded)
print("Intermediate:", hex_text)
print("Decoded:", decoded)
print("Flag:", flag)
```
