地址:
ctf.idf.cn/index.php?g=game&m=list&a=index&id=19
题目:
凯撒加密的
大概就是这样吧,不能告诉你再多了。。
U8Y]:8KdJHTXRI>XU#?!K_ecJH]kJG*bRH7YJH7YSH]*=93dVZ3^S8*$:8"&:9U]RH;g=8Y!U92'=j*$KH]ZSj&[S#!gU#*dK9\.
Writeup:
得知是凯撒加密之后,尝试进行127次轮转爆破:
lstr="""U8Y]:8KdJHTXRI>XU#?!K_ecJH]kJG*bRH7YJH7YSH]*=93dVZ3^S8*$:8"&:9U]RH;g=8Y!U92'=j*$KH]ZSj&[S#!gU#*dK9\."""
for p in range(127):
str1 = ''
for i in lstr:
temp = chr((ord(i)+p)%127)
if 32<ord(temp)<127 :
str1 = str1 + temp
feel = 1
else:
feel = 0
break
if feel == 1:
print(str1)
得出的有用部分如下:
U8Y]:8KdJHTXRI>XU#?!K_ecJH]kJG*bRH7YJH7YSH]*=93dVZ3^S8*$:8"&:9U]RH;g=8Y!U92'=j*$KH]ZSj&[S#!gU#*dK9\.
V9Z^;9LeKIUYSJ?YV$@"L`fdKI^lKH+cSI8ZKI8ZTI^+>:4eW[4_T9+%;9#';:V^SI<h>9Z"V:3(>k+%LI^[Tk'\T$"hV$+eL:]/
W:[_<:MfLJVZTK@ZW%A#MageLJ_mLI,dTJ9[LJ9[UJ_,?;5fX\5`U:,&<:$(<;W_TJ=i?:[#W;4)?l,&MJ_\Ul(]U%#iW%,fM;^0
X;\`=;NgMKW[ULA[X&B$NbhfMK`nMJ-eUK:\MK:\VK`-@<6gY]6aV;-'=;%)=<X`UK>j@;\$X<5*@m-'NK`]Vm)^V&$jX&-gN<_1
Y<]a><OhNLX\VMB\Y'C%OcigNLaoNK.fVL;]NL;]WLa.A=7hZ^7bW<.(><&*>=YaVL?kA<]%Y=6+An.(OLa^Wn*_W'%kY'.hO=`2
Z=^b?=PiOMY]WNC]Z(D&PdjhOMbpOL/gWM<^OM<^XMb/B>8i[_8cX=/)?='+?>ZbWM@lB=^&Z>7,Bo/)PMb_Xo+`X(&lZ(/iP>a3
[>_c@>QjPNZ^XOD^[)E'QekiPNcqPM0hXN=_PN=_YNc0C?9j\`9dY>0*@>(,@?[cXNAmC>_'[?8-Cp0*QNc`Yp,aY)'m[)0jQ?b4
\?`dA?RkQO[_YPE_\*F(RfljQOdrQN1iYO>`QO>`ZOd1D@:k]a:eZ?1+A?)-A@\dYOBnD?`(\@9.Dq1+ROdaZq-bZ*(n\*1kR@c5
]@aeB@SlRP\`ZQF`]+G)SgmkRPesRO2jZP?aRP?a[Pe2EA;l^b;f[@2,B@*.BA]eZPCoE@a)]A:/Er2,SPeb[r.c[+)o]+2lSAd6
^AbfCATmSQ]a[RGa^,H*ThnlSQftSP3k[Q@bSQ@b\Qf3FB<m_c<g\A3-CA+/CB^f[QDpFAb*^B;0Fs3-TQfc\s/d\,*p^,3mTBe7
_BcgDBUnTR^b\SHb_-I+UiomTRguTQ4l\RAcTRAc]Rg4GC=n`d=h]B4.DB,0DC_g\REqGBc+_C<1Gt4.URgd]t0e]-+q_-4nUCf8
`CdhECVoUS_c]TIc`.J,VjpnUShvUR5m]SBdUSBd^Sh5HD>oae>i^C5/EC-1ED`h]SFrHCd,`D=2Hu5/VShe^u1f^.,r`.5oVDg9
aDeiFDWpVT`d^UJda/K-WkqoVTiwVS6n^TCeVTCe_Ti6IE?pbf?j_D60FD.2FEai^TGsIDe-aE>3Iv60WTif_v2g_/-sa/6pWEh:
bEfjGEXqWUae_VKeb0L.XlrpWUjxWT7o_UDfWUDf`Uj7JF@qcg@k`E71GE/3GFbj_UHtJEf.bF?4Jw71XUjg`w3h`0.tb07qXFi;
cFgkHFYrXVbf`WLfc1M/YmsqXVkyXU8p`VEgXVEgaVk8KGArdhAlaF82HF04HGck`VIuKFg/cG@5Kx82YVkhax4ia1/uc18rYGj<
eHimJH[tZXdhbYNhe3O1[ousZXm{ZW:rbXGiZXGicXm:MICtfjCncH:4JH26JIembXKwMHi1eIB7Mz:4[Xmjcz6kc31we3:t[Il>
fIjnKI\u[YeicZOif4P2\pvt[Yn|[X;scYHj[YHjdYn;NJDugkDodI;5KI37KJfncYLxNIj2fJC8N{;5\Ynkd{7ld42xf4;u\Jm?
gJkoLJ]v\Zfjd[Pjg5Q3]qwu\Zo}\Y<tdZIk\ZIkeZo<OKEvhlEpeJ<6LJ48LKgodZMyOJk3gKD9O|<6]Zole|8me53yg5<v]Kn@
hKlpMK^w][gke\Qkh6R4^rxv][p~]Z=ue[Jl][Jlf[p=PLFwimFqfK=7MK59MLhpe[NzPKl4hLE:P}=7^[pmf}9nf64zh6=w^LoA
仔细观察,发现倒数第5行是一串Base64加密,解密得
'the flag is wctf{kaisa_jiaaaaami},plz flow my weibo,http://weibo.com/woldy'
flag = wctf{kaisa_jiaaaaami}