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REVERSE-COMPETITION-NEPCTF
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REVERSE-COMPETITION-NEPCTF hardcsharp 二十六進(jìn)制 easy_mips password worrrrms 勇士打惡龍（unsolved） Qriver（unsolved） Spy-woman（unsolved）
hardcsharp
.Net程序，dnSpy打開，來(lái)到main函數(shù)
from Crypto
. Cipher
import AES
import base64
cipher
= "1Umgm5LG6lNPyRCd0LktJhJtyBN7ivpq+EKGmTAcXUM+0ikYZL4h4QTHGqH/3Wh0"
key
= [ 81 , 82 , 87 , 81 , 82 , 87 , 68 , 92 , 94 , 86 , 93 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 , 18 ]
for i
in range ( len ( key
) ) : key
[ i
] ^ = 51
key_str
= '' . join
( chr ( i
) for i
in key
)
aes
= AES
. new
( key_str
, AES
. MODE_ECB
)
print ( aes
. decrypt
( base64
. b64decode
( cipher
) ) )
二十六進(jìn)制
exe程序，無(wú)殼，ida打開
arr
= "2163qwe)(*&^%489$!057@#><A"
res
= "Fb72>&6"
flag
= [ ]
for i
in range ( len ( res
) ) : v4
= chr ( ord ( res
[ i
] ) ^ 7 ) index
= arr
. find
( v4
) flag
. append
( index
)
sum = 0
for i
in range ( len ( flag
) - 1 , 0 , - 1 ) : sum += flag
[ i
] sum *= 26
sum += flag
[ 0 ]
print ( sum )
調(diào)試驗(yàn)證一下，輸入的數(shù)字正確，md5一下即可提交成功
easy_mips
mips文件，無(wú)殼，ida7.5打開
s
= "3_isjA0UeQZcNa\\`\\Vf"
v3
= 5
flag
= ""
for c
in s
: flag
+= chr ( ord ( c
) + v3
) v3
+= 1
print ( flag
)
password
apk文件，jads-gui打開
#include <stdio.h>
void rc4_init ( unsigned char * s
, unsigned char * key
, unsigned long Len_k
)
{ int i
= 0 , j
= 0 ; char k
[ 256 ] = { 0 } ; unsigned char tmp
= 0 ; for ( i
= 0 ; i
< 256 ; i
++ ) { s
[ i
] = 256 - i
; k
[ i
] = key
[ i
% Len_k
] ; } for ( i
= 0 ; i
< 256 ; i
++ ) { j
= ( j
+ s
[ i
] + k
[ i
] ) % 256 ; tmp
= s
[ i
] ; s
[ i
] = s
[ j
] ; s
[ j
] = tmp
; }
}
void rc4_crypt ( unsigned char * Data
, unsigned long Len_D
, unsigned char * key
, unsigned long Len_k
)
{ unsigned char s
[ 256 ] ; rc4_init ( s
, key
, Len_k
) ; int i
= 0 , j
= 0 , t
= 0 ; unsigned long k
= 0 ; unsigned char tmp
; for ( k
= 0 ; k
< Len_D
; k
++ ) { i
= ( i
+ 1 ) % 256 ; j
= ( j
+ s
[ i
] ) % 256 ; tmp
= s
[ i
] ; s
[ i
] = s
[ j
] ; s
[ j
] = tmp
; t
= ( s
[ i
] + s
[ j
] ) % 256 ; Data
[ k
] = Data
[ k
] ^ s
[ t
] ; }
}
void main ( )
{ unsigned char key
[ ] = "th1s_1s_k3y!!!!!" ; unsigned long key_len
= sizeof ( key
) - 1 ; unsigned char data
[ ] = { 139 , 210 , 217 , 93 , 149 , 255 , 126 , 95 , 41 , 86 , 18 , 185 , 239 , 236 , 139 , 208 , 69 } ; rc4_crypt ( data
, sizeof ( data
) , key
, key_len
) ; for ( int i
= 0 ; i
< sizeof ( data
) ; i
++ ) { printf ( "%c" , data
[ i
] ) ; }
}
用解壓密鑰解壓縮反編譯出來(lái)的\password\assets\flag.zip即可得到flag
worrrrms
exe程序，無(wú)殼，ida打開
from pysm4
import decrypt
from Crypto
. Util
. number
import bytes_to_long
, long_to_bytes
import base64
key
= base64
. b64decode
( "aWNhbnRlbGx1YXNpbXBsZQ==" )
key_long
= bytes_to_long
( key
)
cipher
= 0x021789C8D9DAFBE50E478C894C1D7AB9
m
= decrypt
( cipher
, key_long
)
print ( long_to_bytes
( m
) )
勇士打惡龍（unsolved）
Qriver（unsolved）
Spy-woman（unsolved）
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