Cyptohack Introduction_to_CryptoHack Writeup

str_list = [99, 114, 121, 112, 116, 111, 123, 65, 83, 67, 73, 73, 95, 112, 114, 49, 110, 116, 52, 98, 108, 51, 125]

flag = ""
for i in str_list:
    flag+= chr(i)
    
print(flag)

# crypto{ASCII_pr1nt4bl3}

hex_str = "63727970746f7b596f755f77696c6c5f62655f776f726b696e675f776974685f6865785f737472696e67735f615f6c6f747d"

print(bytes.fromhex(hex_str).decode())
# crypto{You_will_be_working_with_hex_strings_a_lot}

import base64

hex_content = "72bca9b68fc16ac7beeb8f849dca1d8a783e8acf9679bf9269f7bf"

b_c = bytes.fromhex(hex_content)

print(base64.b64encode(b_c).decode())

# crypto/Base+64+Encoding+is+Web+Safe/

from Crypto.Util.number import *

m = 11515195063862318899931685488813747395775516287289682636499965282714637259206269

print(long_to_bytes(m))
# b'crypto{3nc0d1n6_4ll_7h3_w4y_d0wn}'

s = "label"

new_s = ""
for i in s:
    new_s += chr((ord(i) ^ 13))
    
print(f"crypto{{{new_s}}}")
# crypto{aloha}

from pwn import *
s = "label"

new_s = xor(s,13).decode()
print(f"crypto{{{new_s}}}")

# BytesWarning: Text is not bytes; assuming ASCII, no guarantees. See https://docs.pwntools.com/#bytes
#   strs = [packing.flat(s, word_size = 8, sign = False, endianness = 'little') for s in args]
# crypto{aloha}

from pwn import *

k1 = bytes.fromhex("a6c8b6733c9b22de7bc0253266a3867df55acde8635e19c73313")
k12 = bytes.fromhex("37dcb292030faa90d07eec17e3b1c6d8daf94c35d4c9191a5e1e")
k23 = bytes.fromhex("c1545756687e7573db23aa1c3452a098b71a7fbf0fddddde5fc1")
f123 = bytes.fromhex("04ee9855208a2cd59091d04767ae47963170d1660df7f56f5faf")

flag = xor( xor(f123,k23) , k1)
print(flag)
# b'crypto{x0r_i5_ass0c1at1v3}'

c = bytes.fromhex("73626960647f6b206821204f21254f7d694f7624662065622127234f726927756d")

m =b""
for key in range(256):
    m = bytes([b ^ key for b in c])
    if b"crypto" in m:
        print(key)
        print(m)
        break
# 16
# b'crypto{0x10_15_my_f4v0ur173_by7e}'

from pwn import *
c = bytes.fromhex("0e0b213f26041e480b26217f27342e175d0e070a3c5b103e2526217f27342e175d0e077e263451150104")

known_flag = b"crypto{"

known_key_begin = xor( c[0:len(known_flag)] , known_flag )        
# print(known_key_begin)                                      # b'myXORke'

known_key_end = xor( c[-1] , b"}" )                               
# print(known_key_end)                                        # b'y'

key = b'myXORkey'

flag = xor(c,key)

print(flag)
# b'crypto{1f_y0u_Kn0w_En0uGH_y0u_Kn0w_1t_4ll}'