棋盘密码
用一对字母来替代每个明文字母
多文字加密法的密钥是一个5X5的矩阵。这个矩阵的5行和5列用含有5个字母的关键词来标识且该关键词不能有重复的字母。字母表的每一个字母填写在这个矩阵中。矩阵只有25个位置，而字母表有26个字母，因此i和j占同一个单元。这意味着所有j都变成了i。
一个栗子
ilnllliiikkninlekile
长度为20，提示
The length of this plaintext: 10
密文长度是明文的2倍，密文只有5个字母出现，想到多表加密，但不知道表的边缘的排序方式
例如：
l i n k e
l a b c d e
i f g h i k
n l m n o p
k q r s t u
e v w x y z
解密脚本
import itertools
key = []
cipher = "ilnllliiikkninlekile"
for i in itertools.permutations('ilnke', 5):
key.append(''.join(i))
for now_key in key:
solve_c = ""
res = ""
for now_c in cipher:
solve_c += str(now_key.index(now_c))
for i in range(0,len(solve_c),2):
now_ascii = int(solve_c[i])*5+int(solve_c[i+1])+97
if now_ascii>ord('i'):
now_ascii+=1
res += chr(now_ascii)
if "flag" in res:
print now_key,res
四方密码
四方密码用4个5×5的来加密。每个矩阵都有25个字母（通常会取消Q或将I,J视作同一样，或改进为6×6的矩阵，加入10个数字）。首先选择两个英文字作密匙，例如example和keyword。对于每一个密匙，将重复出现的字母去除，即example要转成exampl，然后将每个字母顺序放入矩阵，再将余下的字母顺序放入矩阵，便得出加密矩阵。
将这两个加密矩阵放在右上角和左下角，余下的两个角放a到z顺序的矩阵：
加密的步骤：
- 两个字母一组地分开讯息：（例如helloworld变成he ll ow or ld）
- 找出第一个字母在左上角矩阵的位置
- 找出第二个字母在右下角矩阵的位置
a b c d e E X A M P
f g h i j L B C D F
k l m n o G H I J K
p r s t u N O R S T
v w x y z U V W Y Z
K E Y W O a b c d e
R D A B C f g h i j
F G H I J k l m n o
L M N P S p r s t u
T U V X Z v w x y z
- 如上图所示，则
he加密之后的密文为fy
加密脚本
#coding:utf-8
import collections
import re
matrix = "ABCDEFGHIJKLMNOPRSTUVWXYZ"
pla = "abcdefghijklmnoprstuvwxyz"
key1 = "[EXAMPL]"
key2 = "[KEYWORD]"
key1 = ''.join(collections.OrderedDict.fromkeys(key1))
key2 = ''.join(collections.OrderedDict.fromkeys(key2))
matrix1 = re.sub('[\[\]]','',key1) + re.sub(key1,'',matrix)
matrix2 = re.sub('[\[\]]','',key2) + re.sub(key2,'',matrix)
matrix_list1 = []
matrix_list2 = []
pla_list = []
for i in range(0,len(matrix1),5):
matrix_list1.append(list(matrix1[i:i+5]))
for i in range(0,len(matrix2),5):
matrix_list2.append(list(matrix2[i:i+5]))
for i in range(0,len(pla),5):
pla_list.append(list(pla[i:i+5]))
def find_index(x): #查询明文字母位置
for i in range(len(pla_list)):
for j in range(len(pla_list[i])):
if pla_list[i][j] == x:
return i,j
def gen_cip(letter):
first = find_index(letter[0]) #两个子母中第一个字母位置
second = find_index(letter[1]) #两个子母中第二个字母位置
cip = ""
cip += matrix_list1[first[0]][second[1]]
cip += matrix_list2[second[0]][first[1]]
return cip
def encrypt(pla):
#pla = "whereismysecretkey"
cip = ""
for i in range(0,len(pla),2):
cip += gen_cip(pla[i:i+2])
return cip
def main():
pla = "hello world"
pla = pla.replace(' ','')
print encrypt(pla)
if __name__ == "__main__":
main()
解密脚本
#coding:utf-8
import collections
import re
matrix = "ABCDEFGHIJKLMNOPRSTUVWXYZ"
pla = "abcdefghijklmnoprstuvwxyz"
key1 = "[EXAMPL]"
key2 = "[KEYWORD]"
key1 = ''.join(collections.OrderedDict.fromkeys(key1))
key2 = ''.join(collections.OrderedDict.fromkeys(key2))
matrix1 = re.sub('[\[\]]','',key1) + re.sub(key1,'',matrix)
matrix2 = re.sub('[\[\]]','',key2) + re.sub(key2,'',matrix)
matrix_list1 = []
matrix_list2 = []
pla_list = []
for i in range(0,len(matrix1),5):
matrix_list1.append(list(matrix1[i:i+5]))
for i in range(0,len(matrix2),5):
matrix_list2.append(list(matrix2[i:i+5]))
for i in range(0,len(pla),5):
pla_list.append(list(pla[i:i+5]))
def find_index1(x): #查询两个密文字母位置
for i in range(len(matrix_list1)):
for j in range(len(matrix_list1[i])):
if matrix_list1[i][j] == x:
return i,j
def find_index2(y):
for k in range(len(matrix_list2)):
for l in range(len(matrix_list2[k])):
if matrix_list2[k][l] == y:
return k,l
def gen_pla(letter):
first = find_index1(letter[0]) #两个子母中第一个字母位置
second = find_index2(letter[1]) #两个子母中第二个字母位置
pla = ""
pla += pla_list[first[0]][second[1]]
pla += pla_list[second[0]][first[1]]
return pla
def main():
cip = "FYHGHZHSJE"
pla = ""
for i in range(0,len(cip),2):
pla += gen_pla(cip[i:i+2])
print pla
if __name__ == "__main__":
main()
RSA
题目
#!/usr/bin/python
import random
import string
from hashlib import sha512
from Crypto.Util.number import *
from Crypto.Cipher import AES
import flag
def proof_of_work():
proof = ''.join([random.choice(string.ascii_letters+string.digits)
for _ in xrange(20)])
digest = sha512(proof).hexdigest()
print_output("Proof of your work.\nsha512(%s+XXXX) == %s\n" %
(proof[:-4], digest))
print_output('Tell me XXXX:')
x = raw_input().strip()
if len(x) != 4 or sha512(proof[:-4]+x).hexdigest() != digest:
exit(1)
print_output("OK, you proof.")
return
def egcd(a, b):
if (b == 0):
return 1, 0, a
else:
x, y, q = egcd(b, a % b)
x, y = y, (x - (a // b) * y)
return x, y, q
def mod_inv(a, b):
return egcd(a, b)[0] % b
def print_output(message):
print(message)
sys.stdout.flush()
def rsa_gen(bit_n=2048, bit_e=64):
p = getPrime(bit_n/2)
q = getPrime(bit_n/2)
n = p*q
e = getPrime(bit_e)
d = mod_inv(e, (p-1)*(q-1))
msg = int(''.join([random.choice(string.ascii_letters+string.digits)
for _ in xrange(16)]).encode('hex'), 16)
cipher = pow(msg, e, n)
return e, d, n, msg, cipher
def tell_n_d():
e, d, n, m, c = rsa_gen()
print_output("Give you a message:0x%x\nand its ciphertext:0x%x" % (m, c))
print_output("Please give me the private key to decrypt cipher")
print_output("n:")
N = int(raw_input().strip())
print_output("d:")
D = int(raw_input().strip())
if not pow(c, D, N) == m:
exit(1)
print_output("Oh, how you know the private key!")
return m
def number_theory():
while True:
e, d, n, m, c = rsa_gen()
print_output("n=0x%x\ne=0x%x\nc=0x%x\n" % (n, e, c))
print_output("Now, you have a chance to decrypt something(but no c):")
C = int(raw_input().strip())
if C == c:
print_output("Nonono~")
continue
M = pow(C, d, n)
print_output("message:0x%x" % M)
print_output("Give me right message:")
MM = int(raw_input().strip())
if not MM == m:
exit(1)
print_output("Master in math!")
return m
def pad(s):
return s + ((16-len(s)%16)*chr(16-len(s)%16))
def handle():
proof_of_work()
msg1 = hex(tell_n_d())[2:-1].decode('hex')
msg2 = hex(number_theory())[2:-1].decode('hex')
cipher = AES.new(msg2, AES.MODE_CBC, msg1)
enc = cipher.encrypt(pad(flag.flag))
print_output("Here is your flag:0x%s" % enc.encode('hex'))
if __name__ == "__main__":
handle()
解密脚本
from pwn import *
from hashlib import sha512
import string
import gmpy2 as gm
context.log_level = "debug"
sh = remote("106.75.101.197", 7544)
def proof():
sh.recvline()
tmp = sh.recv()
tmp_str = tmp[7:7+16]
tmp_sha = tmp[-130:].strip()
print tmp_str
print tmp_sha
sha_dict = string.letters + string.digits
for i1 in sha_dict:
for i2 in sha_dict:
for i3 in sha_dict:
for i4 in sha_dict:
res = i1+i2+i3+i4
if(sha512(tmp_str+res).hexdigest()==tmp_sha):
return res
def stage1():
sh.recvline()
m_tmp = sh.recvline()
m = m_tmp[-35:]
log.success("Get the M: %s" %m)
sh.recvuntil("ciphertext:")
c = sh.recv().strip()
log.success("Get the C: %s" %c)
# generate the d, n
m, c = int(m, 16), int(c, 16)
d = 1
n = (c - m) / 2
sh.recvuntil("n:")
sh.sendline(str(n))
sh.recvuntil("d:")
sh.sendline(str(d))
log.success("---STAGE 1 PASS---\n\n")
def stage2():
sh.recvuntil("n=")
n = sh.recvline()
sh.recvuntil("e=")
e = sh.recvline()
sh.recvuntil("c=")
c = sh.recvline()
log.success("Get the N: %s" %n)
log.success("Get the E: %s" %e)
log.success("Get the C: %s" %c)
e,n,c = int(e,16), int(n,16), int(c,16)
sh.recvuntil("no c):")
y = gm.powmod(2, e, n)
y = gm.powmod(c*y, 1, n)
invert_numb = gm.invert(2, n)
sh.sendline(str(y))
sh.recvline()
res =sh.recvline()[8:].strip()
log.success("Get the Decrypt result: %s", res)
res = int(res, 16)
M = gm.powmod(res*invert_numb, 1, n)
sh.recvline()
sh.sendline(str(M))
sh.recv()
res = proof()
log.success("Get the proof result: %s" %res)
sh.recvline()
sh.sendline(res)
stage1()
stage2()
sh.interactive()
