Bise - CTF 85
CTF Name: Bise
Topic: Cryptography
Flag Format: ICTF{}
CTF Link: https://t.me/ctf_invisiblehc/137
Description:
My friend give me a file and he said that this is a binary file. But I can't get the binary code.
Solution:
When we examine the text file given to us in the question, we see that it contains an encrypted text.
We can use the site https://www.dcode.fr/cipher-identifier to find out which type of encrypted it.
After analyzing the cipher, we discovered it was encoded in Base91. After decoding it with a Base91 decoder, we obtained another cipher consisting of only 0 and 1, similar to binary code.
However, it wasn't binary. Further investigation revealed that it was encoded in Brainfuck. We used a Brainfuck decoder and obtained the flag.
Flag: ICTF{B1N4RY_91_B453}
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