BUUCTF-bbbbbbrsa

1. Title code ：

from base64 import b64encode as b32encode
from gmpy2 import invert,gcd,iroot
from Crypto.Util.number import *
from binascii import a2b_hex,b2a_hex
import random

flag = "******************************"

nbit = 128

p = getPrime(nbit)
q = getPrime(nbit)
n = p*q

print p
print n

phi = (p-1)*(q-1)

e = random.randint(50000,70000)

while True:
	if gcd(e,phi) == 1:
		break;
	else:
		e -= 1;

c = pow(int(b2a_hex(flag),16),e,n)

print b32encode(str(c))[::-1]

# 2373740699529364991763589324200093466206785561836101840381622237225512234632



p = 177077389675257695042507998165006460849
n = 37421829509887796274897162249367329400988647145613325367337968063341372726061
c = ==gMzYDNzIjMxUTNyIzNzIjMyYTM4MDM0gTMwEjNzgTM2UTN4cjNwIjN2QzM5ADMwIDNyMTO4UzM2cTM5kDN2MTOyUTO5YDM0czM3MjM

2. Reappear

n,p,c We all know , It's actually blasting e, The scope is also given .

from gmpy2 import invert,gcd
import libnum
p = 177077389675257695042507998165006460849
n = 37421829509887796274897162249367329400988647145613325367337968063341372726061
c = 2373740699529364991763589324200093466206785561836101840381622237225512234632
q=n//p
phi=(p-1)*(q-1)
e=70000
while 1:
    if(e<=1):
        break
    if(gcd(e,phi)==1):
        d=invert(e,phi)
        m=pow(c,d,n)
        if(str(libnum.n2s(int(m)))[2]=='f'):
            print(libnum.n2s(int(m)))
    e=e-1
# b'f\xff\x8e\xaa\x8e\x82\xbd\x0f\x05\x18\xbe\xc5\x82\xd5\x9a\xd8f\xad\x92n\xc6J\xe4\x1a\xb0r=m7\xe6\xac'
# b'flag{rs4_1s_s1mpl3!#}'
# b'f\xcfNT\x9a\x90\xba\xe8\x98\x94\xc5?0\xc5\xa6\x0f5z\xcb\xeew\x07\xff\xab?u`\x91\x1f\xb4 '