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💭
Crypto Newbie :(

# Hyunsik Jeongjhs7jhs

💭
Crypto Newbie :(
Created Oct 19, 2020
simple write-up (oflo, fixed camera, n1vault)
View n1ctf.md

## oflo

There are several anit-reversing logic, so I just patched with `\x90` (nop instruction) to avoid them. After this process, it was able to figure out the logic of the program.

1. Use `/bin/cat` to something to get a string
2. XOR the prologue of a function by the first 5 bytes of the given input.
3. XOR the given input and the string from 1., then check the result is right.

The part 2. is easy to patch, because the first 5 bytes of the given input is always `n1ctf`.

Created Sep 6, 2020
harmagedon
View solver.py
 val = 0xB77C7C ans = [] while val > 0: print(val) val >>= 2 val -= 1 ans.append(val % 4) ans = ans[::-1]
Created Sep 6, 2020
bitcrypto
View solver.py
 from Crypto.Util.number import * from pwn import * r = remote("crypto.kosenctf.com", 13003) r.recvuntil("your query: ") r.sendline('b') l = r.recvuntil('\n') c = [int(x) for x in l.split('[')[1].split(']')[0].split(",")]
Created Sep 6, 2020
View solver.py
 from Crypto.Util.number import * from binascii import unhexlify, hexlify import gmpy2 from pwn import * def get_cube(): sock = remote('crypto.kosenctf.com', 13001) n = int(sock.recvuntil('\n')[3:-1].decode())
Created Jul 19, 2020
XTerm-like color scheme on Windows Terminal
View scheme.json
 { "name": "XTerm-like", "cursorColor": "#ebebeb", "selectionBackground": "#ffffff", "background" : "#000000", "foreground" : "#ebebeb", "black" : "#000000",
Created Jun 12, 2020
View keybase.md

### Keybase proof

I hereby claim:

• I am jhs7jhs on github.
• I am rbtree (https://keybase.io/rbtree) on keybase.
• I have a public key whose fingerprint is 3A77 4E51 675A E05C 40A8 AC1F A3C7 8ADB E4F0 C0DC

To claim this, I am signing this object:

Created May 18, 2020
solver of coooppersmith from DEFCON CTF 2020 Quals
View solver.py
 from pwn import * from ctypes import * from Crypto.PublicKey import RSA from Crypto.Util.number import long_to_bytes as l2b, inverse, GCD as gcd import gmpy2 s = remote("coooppersmith.challenges.ooo", 5000) s.recvuntil(":") s.sendline("1" + "0" * 119)
Created Apr 23, 2020
A PLUS Puzzle (PuzzleScript Script)