NTU CS 2023 HW1 Write Up

Posted on 2024-01-31 | Post modified | In Security Course｜NTU CS｜Crypto |

NTU CS 2023 HW1 Write Up

神盾盃2023初賽

Posted on 2024-01-31 | Post modified | In Security Competition |

神盾盃2023初賽

[23/10/23 更新]: 賽後有和沛凡和asef討論這個題目，終於知道問題出在哪邊，當我們解出$m^3$時，要記得$mod\ n$，然後找到$m$的方式就是暴力搜，暴力搜得意思是因為我們拿到的$m^3$其實是$mod\ N$的結果，代表要找到真正的flag可能要再加上數個$N$才會是原本的flag，也就是$flag \equiv m^3\ (mod\ N)\to flag=k\cdot N+m^3

k\in \mathbb{Z}$，所以我們只要暴力找到那個$k$使得$m^3$開三次方根是整數就代表我們找到真正的flag了

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’

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