2020-全国工业互联网安全技术技能大赛
5G
考查polar编码
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| sub_401FD0();
v3 = time(0);
srand(v3);
memset(&v32, 0, 0x80u);
v30 = (char *)malloc(dword_40F040 + 1);
sub_40E540("%64s", &v32);
v26 = (signed int)(double)sub_4029B0((long double)dword_40F040);
v29 = dword_40F040;
v4 = 4 * (dword_40F040 / 2);
v31 = dword_40F040 / 2;
v5 = malloc(4 * (dword_40F040 / 2));
v28 = malloc(v4);
memcpy(v5, &dword_40F080, v4);
memcpy(v28, (char *)&dword_40F080 + v4, v4);
v6 = 0;
v27 = malloc(4 * v29);
memset(v27, 0, 4 * v29);
v7 = v30;
do
{
LOBYTE(v8) = *((_BYTE *)&v32 + v6);
v9 = 0;
do
{
v10 = v8 & 1;
v8 = (unsigned int)(char)v8 >> 1;
v7[v9++] = v10;
}
while ( v9 != 8 );
++v6;
v7 += 8;
}
while ( v6 != 64 );
|
main函数开始先输入64个字符，然后转换成比特，共512位，进行编码和传输，题目中给了输出可以根据输出进行解码求输入，解码部分根据提示利用开源代码https://github.com/albusSimba/pyPolar实现，但是解码出来的数据位数是1024位，在编码最开始赋值的时候还有一个类似于换表的操作，将512位数据打乱写入1024位的矩阵中，所以解码的时候还需要提取出输入的512位，才可以得到最终结果
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| from QueryPerformanceCounter import *
from polarcodes5G import *
n = 1024
k = n // 2
performance_counter = QueryPerformanceCounter()
myPC = Construct(n, k)
s = "-1.756208 1.027628 -0.952465 -1.638855 -1.462390 0.208588 0.591268 -0.179454 1.095095 0.447900 0.947692 1.350273 -1.155633 -1.938154 0.046054 1.175568 -0.007052 1.220866 1.890119 1.539061 0.677526 -0.493938 1.113000 1.148966 0.437962 -1.025365 -1.001201 -0.274902 0.545109 -1.125495 -1.112381 0.214771 0.635569 …………"
t = [float(i) for i in s.split(" ")]
myPC.llrs = np.array(t)
performance_counter.start()
Decoder(myPC)
performance_counter.end("Decoder")
res = list(myPC.message_received)
bits = list(myPC.msg_bits)
f = [0] * 512
for i, c in enumerate(bits):
f[i] = res[c]
for i in range(0, 512, 8):
ch = 0
for j in range(8):
ch += (f[i + j] << j) & 0xff
print(chr(ch), end="")
|
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