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web/some_assembly_required_4

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This commit is contained in:
Oystein Kristoffer Tveit
2026-07-05 05:03:24 +09:00
parent 3de1d34c20
commit 74008cc0ab
5 changed files with 1032 additions and 0 deletions
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web/some_assembly_required_4/index.html
+12
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@@ -0,0 +1,12 @@
<html>
<head>
<meta charset="UTF-8">
<script src="index.js"></script>
</head>
<body>
<h4>Enter flag:</h4>
<input type="text" id="input"/>
<button onclick="onButtonPress()">Submit</button>
<p id="result"></p>
</body>
</html>
web/some_assembly_required_4/index.js
+66
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@@ -0,0 +1,66 @@
const constants = [
'instance',
'93703gBAUAn',
'442816lLbold',
'instantiate',
'1ZFMVDM',
'381193zsgNYQ',
'check_flag',
'result',
'length',
'48829pZIrMh',
'648920pjyJsd',
'copy_char',
'21760lQoqpJ',
'arrayBuffer',
'1zBwHgR',
'innerHTML',
'615706OhnLTV',
'Correct!',
'getElementById',
'./index.wasm',
'charCodeAt',
];
const getConst = function(addr, _seemingly_unused) {
addr = addr - 0xac;
let result = constants[addr];
return result;
};
// Stack aligner of some sort?
(function() {
while (!![]) {
try {
const result = parseInt(getConst(0xb7)) + parseInt(getConst(0xb0)) + -parseInt(getConst(0xc0)) * parseInt(getConst(0xbd)) + -parseInt(getConst(0xac)) + -parseInt(getConst(0xb3)) + parseInt(getConst(0xb5)) * parseInt(getConst(0xb1)) + -parseInt(getConst(0xbe));
if (result === 0x5b4df) break;
else constants['push'](constants['shift']());
} catch (e) {
constants['push'](constants['shift']());
}
}
}());
let exports;
// Load the WebAssembly module and get its exports
(async () => {
let checkFlagWasm = await fetch('./index.wasm'),
arrayBufferResult = await WebAssembly['instantiate'](await checkFlagWasm['arrayBuffer']()),
arrayBufferResultInstance = arrayBufferResult['instance'];
exports = arrayBufferResultInstance['exports'];
})();
function onButtonPress() {
let value = document['getElementById']('input')['value'];
const copy_char = exports['copy_char'];
for (let i = 0x0; i < value['length']; i++) {
const char_code = value['charCodeAt'](i);
copy_char(char_code, i);
}
exports['copy_char'](0x0, value['length']), exports['check_flag']() == 0x1
? document['getElementById']('result')['innerHTML'] = 'Correct!'
: document['getElementById']('result')['innerHTML'] = 'Incorrect!';
}
web/some_assembly_required_4/index.wasm
BIN
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Binary file not shown.
web/some_assembly_required_4/index.wat
+834
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module
(table $table0 1 1 funcref)
(memory $memory0 2)
(global $global0 (mut i32) (i32.const 66864))
(global $global1 i32 (i32.const 1072))
(global $global2 i32 (i32.const 1024))
(global $global3 i32 (i32.const 1328))
(global $global4 i32 (i32.const 1024))
(global $global5 i32 (i32.const 66864))
(global $global6 i32 (i32.const 0))
(global $global7 i32 (i32.const 1))
(export "memory" (memory $memory0))
(export "__wasm_call_ctors" (func $func0))
(export "strcmp" (func $func1))
(export "check_flag" (func $func2))
(export "input" (global $global1))
(export "copy_char" (func $func3))
(export "__dso_handle" (global $global2))
(export "__data_end" (global $global3))
(export "__global_base" (global $global4))
(export "__heap_base" (global $global5))
(export "__memory_base" (global $global6))
(export "__table_base" (global $global7))
(func $func0
)
(func $func1 (param $var0 i32) (param $var1 i32) (result i32)
(local $var2 i32) (local $var3 i32) (local $var4 i32) (local $var5 i32) (local $var6 i32) (local $var7 i32) (local $var8 i32) (local $var9 i32) (local $var10 i32) (local $var11 i32) (local $var12 i32) (local $var13 i32) (local $var14 i32) (local $var15 i32) (local $var16 i32) (local $var17 i32) (local $var18 i32) (local $var19 i32) (local $var20 i32) (local $var21 i32) (local $var22 i32) (local $var23 i32) (local $var24 i32) (local $var25 i32) (local $var26 i32) (local $var27 i32) (local $var28 i32) (local $var29 i32) (local $var30 i32) (local $var31 i32) (local $var32 i32) (local $var33 i32) (local $var34 i32) (local $var35 i32) (local $var36 i32) (local $var37 i32) (local $var38 i32) (local $var39 i32) (local $var40 i32) (local $var41 i32) (local $var42 i32) (local $var43 i32)
global.get $global0
local.set $var2
i32.const 32
local.set $var3
local.get $var2
local.get $var3
i32.sub
local.set $var4
local.get $var4
local.get $var0
i32.store offset=24
local.get $var4
local.get $var1
i32.store offset=20
local.get $var4
i32.load offset=24
local.set $var5
local.get $var4
local.get $var5
i32.store offset=16
local.get $var4
i32.load offset=20
local.set $var6
local.get $var4
local.get $var6
i32.store offset=12
block $label1
loop $label2
local.get $var4
i32.load offset=16
local.set $var7
i32.const 1
local.set $var8
local.get $var7
local.get $var8
i32.add
local.set $var9
local.get $var4
local.get $var9
i32.store offset=16
local.get $var7
i32.load8_u
local.set $var10
local.get $var4
local.get $var10
i32.store8 offset=11
local.get $var4
i32.load offset=12
local.set $var11
i32.const 1
local.set $var12
local.get $var11
local.get $var12
i32.add
local.set $var13
local.get $var4
local.get $var13
i32.store offset=12
local.get $var11
i32.load8_u
local.set $var14
local.get $var4
local.get $var14
i32.store8 offset=10
local.get $var4
i32.load8_u offset=11
local.set $var15
i32.const 255
local.set $var16
local.get $var15
local.get $var16
i32.and
local.set $var17
block $label0
local.get $var17
br_if $label0
local.get $var4
i32.load8_u offset=11
local.set $var18
i32.const 255
local.set $var19
local.get $var18
local.get $var19
i32.and
local.set $var20
local.get $var4
i32.load8_u offset=10
local.set $var21
i32.const 255
local.set $var22
local.get $var21
local.get $var22
i32.and
local.set $var23
local.get $var20
local.get $var23
i32.sub
local.set $var24
local.get $var4
local.get $var24
i32.store offset=28
br $label1
end $label0
local.get $var4
i32.load8_u offset=11
local.set $var25
i32.const 255
local.set $var26
local.get $var25
local.get $var26
i32.and
local.set $var27
local.get $var4
i32.load8_u offset=10
local.set $var28
i32.const 255
local.set $var29
local.get $var28
local.get $var29
i32.and
local.set $var30
local.get $var27
local.set $var31
local.get $var30
local.set $var32
local.get $var31
local.get $var32
i32.eq
local.set $var33
i32.const 1
local.set $var34
local.get $var33
local.get $var34
i32.and
local.set $var35
local.get $var35
br_if $label2
end $label2
local.get $var4
i32.load8_u offset=11
local.set $var36
i32.const 255
local.set $var37
local.get $var36
local.get $var37
i32.and
local.set $var38
local.get $var4
i32.load8_u offset=10
local.set $var39
i32.const 255
local.set $var40
local.get $var39
local.get $var40
i32.and
local.set $var41
local.get $var38
local.get $var41
i32.sub
local.set $var42
local.get $var4
local.get $var42
i32.store offset=28
end $label1
local.get $var4
i32.load offset=28
local.set $var43
local.get $var43
return
)
(func $func2 (result i32)
(local $var0 i32) (local $var1 i32) (local $var2 i32) (local $var3 i32) (local $var4 i32) (local $var5 i32) (local $var6 i32) (local $var7 i32) (local $var8 i32) (local $var9 i32) (local $var10 i32) (local $var11 i32) (local $var12 i32) (local $var13 i32) (local $var14 i32) (local $var15 i32) (local $var16 i32) (local $var17 i32) (local $var18 i32) (local $var19 i32) (local $var20 i32) (local $var21 i32) (local $var22 i32) (local $var23 i32) (local $var24 i32) (local $var25 i32) (local $var26 i32) (local $var27 i32) (local $var28 i32) (local $var29 i32) (local $var30 i32) (local $var31 i32) (local $var32 i32) (local $var33 i32) (local $var34 i32) (local $var35 i32) (local $var36 i32) (local $var37 i32) (local $var38 i32) (local $var39 i32) (local $var40 i32) (local $var41 i32) (local $var42 i32) (local $var43 i32) (local $var44 i32) (local $var45 i32) (local $var46 i32) (local $var47 i32) (local $var48 i32) (local $var49 i32) (local $var50 i32) (local $var51 i32) (local $var52 i32) (local $var53 i32) (local $var54 i32) (local $var55 i32) (local $var56 i32) (local $var57 i32) (local $var58 i32) (local $var59 i32) (local $var60 i32) (local $var61 i32) (local $var62 i32) (local $var63 i32) (local $var64 i32) (local $var65 i32) (local $var66 i32) (local $var67 i32) (local $var68 i32) (local $var69 i32) (local $var70 i32) (local $var71 i32) (local $var72 i32) (local $var73 i32) (local $var74 i32) (local $var75 i32) (local $var76 i32) (local $var77 i32) (local $var78 i32) (local $var79 i32) (local $var80 i32) (local $var81 i32) (local $var82 i32) (local $var83 i32) (local $var84 i32) (local $var85 i32) (local $var86 i32) (local $var87 i32) (local $var88 i32) (local $var89 i32) (local $var90 i32) (local $var91 i32) (local $var92 i32) (local $var93 i32) (local $var94 i32) (local $var95 i32) (local $var96 i32) (local $var97 i32) (local $var98 i32) (local $var99 i32) (local $var100 i32) (local $var101 i32) (local $var102 i32) (local $var103 i32) (local $var104 i32) (local $var105 i32) (local $var106 i32) (local $var107 i32) (local $var108 i32) (local $var109 i32) (local $var110 i32) (local $var111 i32) (local $var112 i32) (local $var113 i32) (local $var114 i32) (local $var115 i32) (local $var116 i32) (local $var117 i32) (local $var118 i32) (local $var119 i32) (local $var120 i32) (local $var121 i32) (local $var122 i32) (local $var123 i32) (local $var124 i32) (local $var125 i32) (local $var126 i32) (local $var127 i32) (local $var128 i32) (local $var129 i32) (local $var130 i32) (local $var131 i32) (local $var132 i32) (local $var133 i32) (local $var134 i32) (local $var135 i32) (local $var136 i32) (local $var137 i32) (local $var138 i32) (local $var139 i32) (local $var140 i32) (local $var141 i32) (local $var142 i32) (local $var143 i32) (local $var144 i32) (local $var145 i32) (local $var146 i32) (local $var147 i32) (local $var148 i32) (local $var149 i32) (local $var150 i32) (local $var151 i32) (local $var152 i32) (local $var153 i32) (local $var154 i32) (local $var155 i32) (local $var156 i32) (local $var157 i32) (local $var158 i32) (local $var159 i32) (local $var160 i32) (local $var161 i32) (local $var162 i32) (local $var163 i32) (local $var164 i32)
global.get $global0
local.set $var0
i32.const 16
local.set $var1
local.get $var0
local.get $var1
i32.sub
local.set $var2
local.get $var2
global.set $global0
i32.const 0
local.set $var3
local.get $var2
local.get $var3
i32.store offset=12
block $label0
loop $label9
local.get $var2
i32.load offset=12
local.set $var4
local.get $var4
i32.load8_u offset=1072
local.set $var5
i32.const 24
local.set $var6
local.get $var5
local.get $var6
i32.shl
local.set $var7
local.get $var7
local.get $var6
i32.shr_s
local.set $var8
local.get $var8
i32.eqz
br_if $label0
i32.const 0
local.set $var9
local.get $var2
i32.load offset=12
local.set $var10
local.get $var10
i32.load8_u offset=1072
local.set $var11
i32.const 24
local.set $var12
local.get $var11
local.get $var12
i32.shl
local.set $var13
local.get $var13
local.get $var12
i32.shr_s
local.set $var14
i32.const 20
local.set $var15
local.get $var14
local.get $var15
i32.xor
local.set $var16
local.get $var10
local.get $var16
i32.store8 offset=1072
local.get $var2
i32.load offset=12
local.set $var17
local.get $var17
local.set $var18
local.get $var9
local.set $var19
local.get $var18
local.get $var19
i32.gt_s
local.set $var20
i32.const 1
local.set $var21
local.get $var20
local.get $var21
i32.and
local.set $var22
block $label1
local.get $var22
i32.eqz
br_if $label1
local.get $var2
i32.load offset=12
local.set $var23
i32.const 1
local.set $var24
local.get $var23
local.get $var24
i32.sub
local.set $var25
local.get $var25
i32.load8_u offset=1072
local.set $var26
i32.const 24
local.set $var27
local.get $var26
local.get $var27
i32.shl
local.set $var28
local.get $var28
local.get $var27
i32.shr_s
local.set $var29
local.get $var2
i32.load offset=12
local.set $var30
local.get $var30
i32.load8_u offset=1072
local.set $var31
i32.const 24
local.set $var32
local.get $var31
local.get $var32
i32.shl
local.set $var33
local.get $var33
local.get $var32
i32.shr_s
local.set $var34
local.get $var34
local.get $var29
i32.xor
local.set $var35
local.get $var30
local.get $var35
i32.store8 offset=1072
end $label1
i32.const 2
local.set $var36
local.get $var2
i32.load offset=12
local.set $var37
local.get $var37
local.set $var38
local.get $var36
local.set $var39
local.get $var38
local.get $var39
i32.gt_s
local.set $var40
i32.const 1
local.set $var41
local.get $var40
local.get $var41
i32.and
local.set $var42
block $label2
local.get $var42
i32.eqz
br_if $label2
local.get $var2
i32.load offset=12
local.set $var43
i32.const 3
local.set $var44
local.get $var43
local.get $var44
i32.sub
local.set $var45
local.get $var45
i32.load8_u offset=1072
local.set $var46
i32.const 24
local.set $var47
local.get $var46
local.get $var47
i32.shl
local.set $var48
local.get $var48
local.get $var47
i32.shr_s
local.set $var49
local.get $var2
i32.load offset=12
local.set $var50
local.get $var50
i32.load8_u offset=1072
local.set $var51
i32.const 24
local.set $var52
local.get $var51
local.get $var52
i32.shl
local.set $var53
local.get $var53
local.get $var52
i32.shr_s
local.set $var54
local.get $var54
local.get $var49
i32.xor
local.set $var55
local.get $var50
local.get $var55
i32.store8 offset=1072
end $label2
local.get $var2
i32.load offset=12
local.set $var56
i32.const 10
local.set $var57
local.get $var56
local.get $var57
i32.rem_s
local.set $var58
local.get $var2
i32.load offset=12
local.set $var59
local.get $var59
i32.load8_u offset=1072
local.set $var60
i32.const 24
local.set $var61
local.get $var60
local.get $var61
i32.shl
local.set $var62
local.get $var62
local.get $var61
i32.shr_s
local.set $var63
local.get $var63
local.get $var58
i32.xor
local.set $var64
local.get $var59
local.get $var64
i32.store8 offset=1072
local.get $var2
i32.load offset=12
local.set $var65
i32.const 2
local.set $var66
local.get $var65
local.get $var66
i32.rem_s
local.set $var67
block $label4
block $label3
local.get $var67
br_if $label3
local.get $var2
i32.load offset=12
local.set $var68
local.get $var68
i32.load8_u offset=1072
local.set $var69
i32.const 24
local.set $var70
local.get $var69
local.get $var70
i32.shl
local.set $var71
local.get $var71
local.get $var70
i32.shr_s
local.set $var72
i32.const 9
local.set $var73
local.get $var72
local.get $var73
i32.xor
local.set $var74
local.get $var68
local.get $var74
i32.store8 offset=1072
br $label4
end $label3
local.get $var2
i32.load offset=12
local.set $var75
local.get $var75
i32.load8_u offset=1072
local.set $var76
i32.const 24
local.set $var77
local.get $var76
local.get $var77
i32.shl
local.set $var78
local.get $var78
local.get $var77
i32.shr_s
local.set $var79
i32.const 8
local.set $var80
local.get $var79
local.get $var80
i32.xor
local.set $var81
local.get $var75
local.get $var81
i32.store8 offset=1072
end $label4
local.get $var2
i32.load offset=12
local.set $var82
i32.const 3
local.set $var83
local.get $var82
local.get $var83
i32.rem_s
local.set $var84
block $label6
block $label5
local.get $var84
br_if $label5
local.get $var2
i32.load offset=12
local.set $var85
local.get $var85
i32.load8_u offset=1072
local.set $var86
i32.const 24
local.set $var87
local.get $var86
local.get $var87
i32.shl
local.set $var88
local.get $var88
local.get $var87
i32.shr_s
local.set $var89
i32.const 7
local.set $var90
local.get $var89
local.get $var90
i32.xor
local.set $var91
local.get $var85
local.get $var91
i32.store8 offset=1072
br $label6
end $label5
i32.const 1
local.set $var92
local.get $var2
i32.load offset=12
local.set $var93
i32.const 3
local.set $var94
local.get $var93
local.get $var94
i32.rem_s
local.set $var95
local.get $var95
local.set $var96
local.get $var92
local.set $var97
local.get $var96
local.get $var97
i32.eq
local.set $var98
i32.const 1
local.set $var99
local.get $var98
local.get $var99
i32.and
local.set $var100
block $label8
block $label7
local.get $var100
i32.eqz
br_if $label7
local.get $var2
i32.load offset=12
local.set $var101
local.get $var101
i32.load8_u offset=1072
local.set $var102
i32.const 24
local.set $var103
local.get $var102
local.get $var103
i32.shl
local.set $var104
local.get $var104
local.get $var103
i32.shr_s
local.set $var105
i32.const 6
local.set $var106
local.get $var105
local.get $var106
i32.xor
local.set $var107
local.get $var101
local.get $var107
i32.store8 offset=1072
br $label8
end $label7
local.get $var2
i32.load offset=12
local.set $var108
local.get $var108
i32.load8_u offset=1072
local.set $var109
i32.const 24
local.set $var110
local.get $var109
local.get $var110
i32.shl
local.set $var111
local.get $var111
local.get $var110
i32.shr_s
local.set $var112
i32.const 5
local.set $var113
local.get $var112
local.get $var113
i32.xor
local.set $var114
local.get $var108
local.get $var114
i32.store8 offset=1072
end $label8
end $label6
local.get $var2
i32.load offset=12
local.set $var115
i32.const 1
local.set $var116
local.get $var115
local.get $var116
i32.add
local.set $var117
local.get $var2
local.get $var117
i32.store offset=12
br $label9
end $label9
end $label0
i32.const 0
local.set $var118
local.get $var2
local.get $var118
i32.store offset=4
block $label10
loop $label12
local.get $var2
i32.load offset=4
local.set $var119
local.get $var2
i32.load offset=12
local.set $var120
local.get $var119
local.set $var121
local.get $var120
local.set $var122
local.get $var121
local.get $var122
i32.lt_s
local.set $var123
i32.const 1
local.set $var124
local.get $var123
local.get $var124
i32.and
local.set $var125
local.get $var125
i32.eqz
br_if $label10
local.get $var2
i32.load offset=4
local.set $var126
i32.const 2
local.set $var127
local.get $var126
local.get $var127
i32.rem_s
local.set $var128
block $label11
local.get $var128
br_if $label11
local.get $var2
i32.load offset=4
local.set $var129
i32.const 1
local.set $var130
local.get $var129
local.get $var130
i32.add
local.set $var131
local.get $var2
i32.load offset=12
local.set $var132
local.get $var131
local.set $var133
local.get $var132
local.set $var134
local.get $var133
local.get $var134
i32.lt_s
local.set $var135
i32.const 1
local.set $var136
local.get $var135
local.get $var136
i32.and
local.set $var137
local.get $var137
i32.eqz
br_if $label11
local.get $var2
i32.load offset=4
local.set $var138
local.get $var138
i32.load8_u offset=1072
local.set $var139
local.get $var2
local.get $var139
i32.store8 offset=11
local.get $var2
i32.load offset=4
local.set $var140
i32.const 1
local.set $var141
local.get $var140
local.get $var141
i32.add
local.set $var142
local.get $var142
i32.load8_u offset=1072
local.set $var143
local.get $var2
i32.load offset=4
local.set $var144
local.get $var144
local.get $var143
i32.store8 offset=1072
local.get $var2
i32.load8_u offset=11
local.set $var145
local.get $var2
i32.load offset=4
local.set $var146
i32.const 1
local.set $var147
local.get $var146
local.get $var147
i32.add
local.set $var148
local.get $var148
local.get $var145
i32.store8 offset=1072
end $label11
local.get $var2
i32.load offset=4
local.set $var149
i32.const 1
local.set $var150
local.get $var149
local.get $var150
i32.add
local.set $var151
local.get $var2
local.get $var151
i32.store offset=4
br $label12
end $label12
end $label10
i32.const 0
local.set $var152
i32.const 1072
local.set $var153
i32.const 1024
local.set $var154
local.get $var154
local.get $var153
call $func1
local.set $var155
local.get $var155
local.set $var156
local.get $var152
local.set $var157
local.get $var156
local.get $var157
i32.ne
local.set $var158
i32.const -1
local.set $var159
local.get $var158
local.get $var159
i32.xor
local.set $var160
i32.const 1
local.set $var161
local.get $var160
local.get $var161
i32.and
local.set $var162
i32.const 16
local.set $var163
local.get $var2
local.get $var163
i32.add
local.set $var164
local.get $var164
global.set $global0
local.get $var162
return
)
(func $func3 (param $var0 i32) (param $var1 i32)
(local $var2 i32) (local $var3 i32) (local $var4 i32) (local $var5 i32) (local $var6 i32)
global.get $global0
local.set $var2
i32.const 16
local.set $var3
local.get $var2
local.get $var3
i32.sub
local.set $var4
local.get $var4
local.get $var0
i32.store offset=12
local.get $var4
local.get $var1
i32.store offset=8
local.get $var4
i32.load offset=12
local.set $var5
local.get $var4
i32.load offset=8
local.set $var6
local.get $var6
local.get $var5
i32.store8 offset=1072
return
)
(data (i32.const 1024) "\18j|a\118i7\1fYyY>\1cVc\0dB\1d~l9\1cZ!]c\11\00b\05IK~a4\1cW(\0fR\00\00")
)
web/some_assembly_required_4/solve.py
+120
View File
@@ -0,0 +1,120 @@
# OUTPUT FROM GHIDRA WITH WASM EXTENSION:
#
# byte export::check_flag(void)
# {
# int strcmp_result;
# int j;
# int i;
# undefined1 c;
#
# for (i = 0; (&ram_result_buf)[i] != '\0'; i = i + 1) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 0x14;
# if (0 < i) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ (&DA T_ram_0000042f)[i];
# }
# if (2 < i) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ (&DA T_ram_0000042d)[i];
# }
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ (byte) (i % 10);
# if (i % 2 == 0) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 9;
# }
# else {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 8;
# }
# if (i % 3 == 0) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 7;
# }
# else if (i % 3 == 1) {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 6;
# }
# else {
# (&ram_result_buf)[i] = (&ram_result_buf)[i] ^ 5;
# }
# }
# for (j = 0; j < i; j = j + 1) {
# if ((j % 2 == 0) && (j + 1 < i)) {
# c = (&ram_result_buf)[j];
# (&ram_result_buf)[j] = (&ram_result_buf_plus1)[j];
# (&ram_result_buf_plus1)[j] = c;
# }
# }
# strcmp_result = strcmp((char *)0x400,&ram_result _buf);
# return (strcmp_result != 0 ^ 0xffU) & 1;
# }
INPUT_0400 = b"\x18j|a\x118i7\x1fYyY>\x1cVc\x0dB\x1d~l9\x1cZ!]c\x11\x00b\x05IK~a4\x1cW(\x0fR"
def check_flag(flag: bytes) -> bool:
ram_result_buf = bytearray(flag)
i = 0
while i < len(ram_result_buf) and ram_result_buf[i] != 0:
ram_result_buf[i] ^= 0x14
if i > 0:
ram_result_buf[i] ^= ram_result_buf[i - 1]
if i > 2:
ram_result_buf[i] ^= ram_result_buf[i - 3]
ram_result_buf[i] ^= (i % 10)
if i % 2 == 0:
ram_result_buf[i] ^= 9
else:
ram_result_buf[i] ^= 8
if i % 3 == 0:
ram_result_buf[i] ^= 7
elif i % 3 == 1:
ram_result_buf[i] ^= 6
else:
ram_result_buf[i] ^= 5
i += 1
for j in range(len(ram_result_buf)):
if (j % 2 == 0) and (j + 1 < i):
ram_result_buf[j], ram_result_buf[j + 1] = ram_result_buf[j + 1], ram_result_buf[j]
return bytes(ram_result_buf) == INPUT_0400
def recover_flag() -> bytes:
recovered_flag = bytearray(INPUT_0400)
for j in range(0, len(recovered_flag)):
if (j % 2 == 0) and (j + 1 < len(recovered_flag)):
recovered_flag[j], recovered_flag[j + 1] = recovered_flag[j + 1], recovered_flag[j]
for i in reversed(range(len(recovered_flag))):
if i % 3 == 0:
recovered_flag[i] ^= 7
elif i % 3 == 1:
recovered_flag[i] ^= 6
else:
recovered_flag[i] ^= 5
if i % 2 == 0:
recovered_flag[i] ^= 9
else:
recovered_flag[i] ^= 8
recovered_flag[i] ^= (i % 10)
if i > 2:
recovered_flag[i] ^= recovered_flag[i - 3]
if i > 0:
recovered_flag[i] ^= recovered_flag[i - 1]
recovered_flag[i] ^= 0x14
return bytes(recovered_flag)
def main():
flag = recover_flag()
print(f"Recovered flag: {flag.decode()}")
if __name__ == "__main__":
main()