چالش trendy_windy_trigonity¶

from Crypto.Util.number import bytes_to_long

flag = REDACTED
print(len(flag))

R = RealField(1000)
a, b = bytes_to_long(flag[:len(flag)//2]), bytes_to_long(flag[len(flag)//2:])
x = R(0.75872961153339387563860550178464795474547887323678173252494265684893323654606628651427151866818730100357590296863274236719073684620030717141521941211167282170567424114270941542016135979438271439047194028943997508126389603529160316379547558098144713802870753946485296790294770557302303874143106908193100)

enc = a*cos(x)+b*sin(x)

# 38
# 2.78332652222000091147933689155414792020338527644698903976732528036823470890155538913578083110732846416012108159157421703264608723649277363079905992717518852564589901390988865009495918051490722972227485851595410047572144567706501150041757189923387228097603575500648300998275877439215112961273516978501e45

from Crypto.Util.number import long_to_bytes
from sage.all import *

m = 10 ** 300    # both enc and x has a decimal point of 300
R = RealField(1000)
enc = R("2.78332652222000091147933689155414792020338527644698903976732528036823470890155538913578083110732846416012108159157421703264608723649277363079905992717518852564589901390988865009495918051490722972227485851595410047572144567706501150041757189923387228097603575500648300998275877439215112961273516978501e45")
x = R("0.75872961153339387563860550178464795474547887323678173252494265684893323654606628651427151866818730100357590296863274236719073684620030717141521941211167282170567424114270941542016135979438271439047194028943997508126389603529160316379547558098144713802870753946485296790294770557302303874143106908193100")

enc = int(enc * m)
cos_x = int(cos(x) * m)
sin_x = int(sin(x) * m)

M = Matrix(ZZ,[
    [cos_x, sin_x, -enc],
    [ 1   ,   0  ,   0],
    [ 0   ,   1  ,   0],    
]).T

vecs = M.LLL()
for vec in vecs:
    a, b = vec[1], vec[2]
    flag = long_to_bytes(abs(int(a))) + long_to_bytes(abs(int(b)))
    if b'CSCTF{' in flag:
        print(flag)