[SWPUCTF] 2021 Freshman Competition Crypto chapter record (11)

NSSCTF platform: https://www.nssctf.cn/

PS: Remember to flagchange everything toNSSCTF

[SWPUCTF 2021 Freshmen Competition] crypto6

A string of character strings BaseFamily Matryoshka is encrypted and finally Base64decrypted flag.

var="************************************"
flag='NSSCTF{' + base64.b16encode(base64.b32encode(base64.b64encode(var.encode()))) + '}'
print(flag)

4A5A4C564B36434E4B5241544B5432454E4E32465552324E47424758534D44594C4657564336534D4B5241584F574C4B4B463245365643424F35485649534C584A5A56454B4D4B5049354E47593D3D3D

NSSCTF{5e110989-dc43-1bd3-00b4-9009206158fe}

[SWPUCTF 2021 Freshman Competition] ez_caesar

After downloading a pyscript, the input value is first Base64decoded and finally obtained by Caesar decryption flag.

NSSCTF{youhaveknowcaesar}

[SWPUCTF 2021 Freshmen Competition] crypto10

Decrypt directly ROT13, just go with the flow

NSSCTF{congratulations!!!}

[SWPUCTF 2021 Freshman Competition] pigpig

The pigsty password can be found directly by referring to the corresponding picture flag.

Pigpen password online decryption website: http://www.metools.info/code/c90.html

NSSCTF{whenthepigwanttoeat}

[SWPUCTF 2021 Freshman Competition]traditional

Leibniz, the inventor of binary mathematics in the West, was inspired by the Chinese Eight Diagrams, deduced and deduced the mathematical matrix, and finally created binary mathematics. The birth of binary mathematics laid the theoretical foundation for the invention of computers. And the computer has changed our whole world and our life now, but its source comes from the Eight Diagrams. Now, given you a set of ciphertexts composed of the directions of the eight diagrams, can you decipher the meaning? Zhen Kun Gen Zhen Gen Zhen Kun Xun Kun Kun Xun Zhen Zhen Xun Dui Zhen Gen Zhen Zhen Li Gen Zhen Zhen Li Gen

The deciphering of the gossip diagram is based on the judgment on the gossip diagram, and the difference between yin and yang is converted into 0a 1sum (binary) and then compared according to the topic

This kind of binary is: 001000100 001100001 000110000 000110001 001110011 001100001 001101100 001101100
decimal is: 68 97 48 49 115 97 108 108converted to asciicode

NSSCTF{Da01sall}

[SWPUCTF 2021 Freshmen Competition] crypto2

> from gmpy2 import * from Crypto.Util.number import *
> 
> 
> 
> flag  = '***************'
> 
> p = getPrime(512) q = getPrime(512) m1 =
> bytes_to_long(bytes(flag.encode()))
> 
> 
> n = p*q e1 = getPrime(32) e2 = getPrime(32) print()
> 
> flag1 = pow(m1,e1,n) flag2 = pow(m1,e2,n) print('flag1= '+str(flag1))
> print('flag2= '+str(flag2)) print('e1= ' +str(e1)) print('e2=
> '+str(e2)) print('n= '+str(n))
> 
> 
> #flag1= 100156221476910922393504870369139942732039899485715044553913743347065883159136513788649486841774544271396690778274591792200052614669235485675534653358596366535073802301361391007325520975043321423979924560272762579823233787671688669418622502663507796640233829689484044539829008058686075845762979657345727814280
> #flag2= 86203582128388484129915298832227259690596162850520078142152482846864345432564143608324463705492416009896246993950991615005717737886323630334871790740288140033046061512799892371429864110237909925611745163785768204802056985016447086450491884472899152778839120484475953828199840871689380584162839244393022471075
> #e1= 3247473589
> #e2= 3698409173
> #n= 103606706829811720151309965777670519601112877713318435398103278099344725459597221064867089950867125892545997503531556048610968847926307322033117328614701432100084574953706259773711412853364463950703468142791390129671097834871371125741564434710151190962389213898270025272913761067078391308880995594218009110313

[SWPUCTF 2021 Freshman Competition] ez_rsa

p = 1325465431
q = 152317153
e = 65537
Calculate d, encrypt d with MD5 and wrap it in NSSCTF{} to submit

import gmpy2
p = 1325465431
q = 152317153
e = 65537

a = (p - 1) * (q - 1)
b = gmpy2.invert(e,a)

print(b)
#最后别忘了md5加密一下

NSSCTF{08bb8fb628da85923e5734a75ac19ffe}

[Crane City Cup 2021] A_CRYPTO

Matryoshka decryption:Rot13---Base16--Base32-Base64-Base64

4O595954494Q32515046324757595N534R52415653334357474R4N575955544R4O5N4Q46434S4O59474253464Q5N444R4Q51334557524O5N4S424944473542554O595N44534O324R49565746515532464O49345649564O464R4R494543504N35
## Rot13
4B595954494D32515046324757595A534E52415653334357474E4A575955544E4B5A4D46434F4B59474253464D5A444E4D51334557524B5A4F424944473542554B595A44534B324E49565746515532464B49345649564B464E4E494543504A35
##  Base16
KYYTIM2QPF2GWYZSNRAVS3CWGNJWYUTNKZMFCOKYGBSFMZDNMQ3EWRKZOBIDG5BUKYZDSK2NIVWFQU2FKI4VIVKFNNIECPJ5
##  Base32
V143Pytkc2lAYlV3SlRmVXQ9X0dVdmd6KEYpP3t4V29+MElXSER9TUEkPA==

##  Base64
W^7?+dsi@bUwJTfUt=_GUvgz(F)?{
    
    xWo~0IWHD}MA$<

flag{W0w_y0u_c4n_rea11y_enc0d1ng!}

[BJDCTF 2020]base??

import base64
dict={
    
    0: 'J', 1: 'K', 2: 'L', 3: 'M', 4: 'N', 5: 'O', 6: 'x', 7: 'y', 8: 'U', 9: 'V', 10: 'z', 11: 'A', 12: 'B', 13: 'C', 14: 'D', 15: 'E', 16: 'F', 17: 'G', 18: 'H', 19: '7', 20: '8', 21: '9', 22: 'P', 23: 'Q', 24: 'I', 25: 'a', 26: 'b', 27: 'c', 28: 'd', 29: 'e', 30: 'f', 31: 'g', 32: 'h', 33: 'i', 34: 'j', 35: 'k', 36: 'l', 37: 'm', 38: 'W', 39: 'X', 40: 'Y', 41: 'Z', 42: '0', 43: '1', 44: '2', 45: '3', 46: '4', 47: '5', 48: '6', 49: 'R', 50: 'S', 51: 'T', 52: 'n', 53: 'o', 54: 'p', 55: 'q', 56: 'r', 57: 's', 58: 't', 59: 'u', 60: 'v', 61: 'w', 62: '+', 63: '/', 64: '='}
base64_list = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P','Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f','g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/']
cipher='FlZNfnF6Qol6e9w17WwQQoGYBQCgIkGTa9w3IQKw'
res=''
for i in range(len(cipher)):
    for j in range(64):
        if(dict[j]==cipher[i]):
            res+=base64_list[j]
flag=base64.b64decode(res)
print(flag)

NSSCTF{D0_Y0u_kNoW_Th1s_b4se_map}