Welcome ๐Ÿ‘‹

Hello, I’m Hyunsik Jeong a.k.a. RBTree. I mainly write articles related to cryptography, reverse engineering, and other CTF/security-related stuffs here.

2022 ํšŒ๊ณ  ๋ฐ 2023๋…„ ๋ชฉํ‘œ

์šฐ์šธํ•จ์˜ ๊ณ ๋ฆฌ๋ฅผ ๋Š์œผ๋ฉฐ ์ž‘๋…„ ํšŒ๊ณ  ๊ธ€์„ ๋ณด๋‹ˆ ์—„์ฒญ ํž˜๋“ค์—ˆ๋˜ ๊ฑฐ ๊ฐ™์Šต๋‹ˆ๋‹ค. ์‚ฌ์‹ค ์ด ์ƒํƒœ๊ฐ€ ์˜ฌํ•ด ๋“ค์–ด์„œ๋„ ๋งŽ์ด ๋‚˜์•„์ง€์ง€ ์•Š์•˜์—ˆ๋Š”๋ฐ, ํ›ˆ๋ จ์†Œ๋ฅผ ๋‹ค๋…€์˜จ ์ „ํ›„๋กœ ๋ญ”๊ฐ€ ๊นจ๋‹ฌ์Œ์ด...

2023-01-03 ยท 2 min ยท RBTree

ํ›„์ง€ํ ํ•˜์ด๋žœ๋“œ(ๅฏŒๅฃซๆ€ฅใƒใ‚คใƒฉใƒณใƒ‰) ํ›„๊ธฐ

2022๋…„ 12์›” 10์ผ, ํ™€๋กœ๋ผ์ด๋ธŒ ์ฝœ๋ผ๋ณด ๋ฐฉ๋ฌธ์„ ์œ„ํ•ด์„œ ํ›„์ง€ํ ํ•˜์ด๋žœ๋“œ์— ๋‹ค๋…€์™”์Šต๋‹ˆ๋‹ค! ์ด๋ฒˆ์— ๋‹ค๋…€์˜ค๋ฉด์„œ ์ค€๋น„ํ–ˆ๋˜ ๋ฌผํ’ˆ, ๊ทธ๋ฆฌ๊ณ  ์ฝœ๋ผ๋ณด ๊ด€๋ จํ•ด์„œ ์ •๋ฆฌํ•ด๋ณด...

2022-12-19 ยท 5 min ยท RBTree

Interpolation Attack

I made one crypto challenge each for CODEGATE CTF 2022 quals and finals. In this article, Iโ€™m gonna explain how the interpolation attack works, and show the way to solve my challenge โ€œHidden Command Serviceโ€ from the finals. Interpolation Attack Once upon a time, there was a dangerous attack technique called โ€˜differential cryptanalysisโ€™โ€ฆ Then, two crypto-magicians made a scheme which is provably safe from the differential cryptanalysis, called KN-Cipher. However, it soon turned out that the structure of S-boxes used in those ciphers are vulnerable to a new attack called โ€˜interpolation attackโ€™, and a variant of KN-Cipher called PURE is broken....

2022-11-07 ยท 10 min ยท RBTree

Cube Attack

I made one crypto challenge each for CODEGATE CTF 2022 quals and finals. In this article, Iโ€™m gonna explain how the cube attack works, and show the way to solve my challenge โ€œHappy S-boxโ€ from the quals. Cube Attack Consider a multivariate equation over $\text{GF}(2)$, $f(x_1, \dots, x_n)$. There will be multiple monomials in $f$, and what we want to do is to pick one monomial $g = x_{i_1}x_{i_2} \cdots x_{i_k}$ and divide $f$ by $g$....

2022-11-07 ยท 6 min ยท RBTree

์ „๋ฌธ์—ฐ๊ตฌ์š”์›์„ ์œ„ํ•œ ํ›ˆ๋ จ์†Œ ์ค€๋น„๋ฌผ ๋ฐ ํŒ

2022๋…„ 7์›” 7์ผ์— ํ›ˆ๋ จ์†Œ์— ์ž…์†Œํ•ด์„œ 7์›” 28์ผ์— ํ‡ด์†Œํ–ˆ์Šต๋‹ˆ๋‹ค. ๋‹คํ–‰ํžˆ๋„ ์ข‹์€ ์‚ฌ๋žŒ๋“ค๊ณผ ๊ฐ™์€ ๋ถ„๋Œ€์—์„œ ์ƒํ™œํ•ด์„œ ์ž˜ ์ง€๋‚ผ ์ˆ˜ ์žˆ์—ˆ์Šต๋‹ˆ๋‹ค. ์ด ๊ธ€์—์„œ๋Š” ๊ฐœ์ธ์ ์œผ...

2022-07-31 ยท 6 min ยท RBTree