Tags: rsa crypto 

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TLDR
- We are given the KeyGen function, notice that one prime is much larger than the other, so factoring n is possible.

- Recover n by asking for the encryption of -1. Assume e is small and recover it by solving the dlog by enumeration. Factor n.

- Compute d (as usual) and decrypt using Square and Multiply adapted for the Complex numbers.

Read complete writeup: [https://sectt.github.io/writeups/CryptoCTF19/crypto_complexrsa/README](https://sectt.github.io/writeups/CryptoCTF19/crypto_complexrsa/README)