密码学实验DES的C语言实现-创新互联
#includevoid F(int R[32], int K[48]);
void S(int f[48]);
void replace(int *a, int *ans,int *biao, int m);
void lfMove(int *a, int n);
int Get(int r);
//DES
void shizhuaner(int *a,int x);
void S_box(int a[48],int b[32]);
void DES(int *m, int *k, int c[64]);
int IP[64] = { 58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7 };
int IP_1[64] = { 40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25 };
int zhihuan1[56] = { 57, 49, 41, 33, 25, 17, 9,
1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27,
19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15,
7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29,
21, 13, 5, 28, 20, 12, 4 };
int zhihuan2[48] = { 14, 17, 11, 24, 1, 5,
3, 28, 15, 6, 21, 10,
23, 19, 12, 4, 26, 8,
16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55,
30, 40, 51, 45, 33, 48,
44, 49, 39, 56, 34, 53,
46, 42, 50, 36, 29, 32 };
int e[48] = { 32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1 };
int P[32] = { 16, 7, 20, 21, 29, 12, 28, 17,
1, 15, 23, 26, 5, 18, 31, 10,
2, 8, 24, 14, 32, 27, 3, 9,
19, 13, 30, 6, 22, 11, 4, 25 };
void replace(int *a, int *ans, int *biao, int m)
{
int i;
for(i = 0; i< m; i++) {
ans[i] = a[biao[i] - 1];
}
return;
}
int Get(int r)
{
int i;
if (r==1||r==2||r==9||r==16) i=1;
else i=2;
return i;
}
void lfMove(int a[28], int n) {
int i, j;
int temp;
for(j = 0; j< n; j++) {
temp = a[0];
for(i = 0; i< 28; i++) {
a[i] = a[i + 1];
}
a[27] = temp;
}
return;
}
void Nor48(int a[48], int b[48]) {
int i;
for(i = 0; i< 48; i++) {
if(a[i] != b[i]) {
a[i] = 1;
} else {
a[i] = 0;
}
}
return;
}
void Nor32(int a[32], int b[32]) {
int i;
for(i = 0; i< 48; i++) {
if(a[i] != b[i]) {
a[i] = 1;
} else {
a[i] = 0;
}
}
return;
}
void shizhuaner(int a[4], int x)
{
int i;
for(i = 3; i >= 0; i--) {
a[i] = x % 2;
x = x / 2;
}
return;
}
void S_box(int a[48],int b[32])
{
int x, y;
int temp, temp1[4];
int s1[4][16] = { { 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 },
{ 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8 },
{ 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0 },
{ 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 } };
int s2[4][16] = { { 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 },
{ 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 },
{ 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 },
{ 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 } };
int s3[4][16] = { { 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 },
{ 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 },
{ 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7 },
{ 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 } };
int s4[4][16] = { { 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 },
{ 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 },
{ 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 3 },
{ 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 } };
int s5[4][16] = { { 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 },
{ 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 },
{ 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14 },
{ 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 } };
int s6[4][16] = { { 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 },
{ 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 },
{ 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6 },
{ 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 } };
int s7[4][16] = { { 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 },
{ 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 },
{ 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2 },
{ 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 } };
int s8[4][16] = { { 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 },
{ 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 },
{ 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8 },
{ 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 } };
int i;
for(i = 0; i< 8; i++) {
x = 2 * a[i * 6] + a[i * 6 + 5];
y = 8 * a[i * 6 + 1] + 4 * a[i * 6 + 2] + 2 * a[i * 6 + 3] + a[i * 6 + 4];
switch(i)
{
case 0:temp = s1[x][y]; break;
case 1:temp = s2[x][y]; break;
case 2:temp = s3[x][y]; break;
case 3:temp = s4[x][y]; break;
case 4:temp = s5[x][y]; break;
case 5:temp = s6[x][y]; break;
case 6:temp = s7[x][y]; break;
case 7:temp = s8[x][y]; break;
}
shizhuaner(temp1, temp);//fault
for(int j = 0; j< 4; j++) {
b[(i * 4) + j] = temp1[j];
}
}
}
void DES(int *m, int *k, int c[64]) {
int m1[64];
int left[32], right[32];
int temp1[32];
int temp2[32];
int temp3[64];
int k1[56];
int C[28], D[28];
int temp[48];
int newk[48];
int ans[64];
int i;
replace(k, k1, zhihuan1, 56);//zhihuan1 is right
// for(i = 0; i< 56; i++) {
// printf("%3d", k1[i]);
// if((i + 1) % 8 == 0) printf("\n");
// }printf("\n");
for(i = 0; i< 28; i++) {
C[i] = k1[i];
D[i] = k1[i + 28];
}//correct
// for(i = 0; i< 28; i++) {
// printf("%3d", D[i]);
// if((i + 1) % 8 == 0) printf("\n");
// }printf("\n");
replace(m, m1, IP, 64);//ip is right
for(i = 0; i< 32; i++) {
left[i] = m1[i];
right[i] = m1[i + 32];
}
for(i = 1; i< 17; i++) {
int n = Get(i);
lfMove(C, n);
lfMove(D, n);//lfmove is correct
for(int j = 0; j< 28; j++) {
temp3[j] = C[j];
temp3[j + 28] = D[j];
}//correct
replace(temp3, newk, zhihuan2, 48);//correct, k is always right
if(i == 16) {
printf("right:");
for(int j = 0; j< 32; j++) {
printf("%d", right[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
replace(right, temp, e, 48);//correct
if(i == 16) {
printf("temp :");
for(int j = 0; j< 48; j++) {
printf("%d", temp[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
if(i == 16) {
printf("key :");
for(int j = 0; j< 48; j++) {
printf("%d", newk[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
Nor48(temp, newk);
if(i == 16) {
printf("after nor :");
for(int j = 0; j< 48; j++) {
printf("%d", temp[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
S_box(temp, temp1);//fault
if(i == 16) {
printf("after S :");
for(int j = 0; j< 32; j++) {
printf("%d", temp1[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
replace(temp1, temp2, P, 48);
if(i == 16) {
printf("P :");
for(int j = 0; j< 32; j++) {
printf("%d", temp2[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
Nor32(temp2, left);
for(int j = 0; j< 32; j++) left[j] = right[j];
for(int j = 0; j< 32; j++) right[j] = temp2[j];
if(i == 16) {
printf("left :");
for(int j = 0; j< 32; j++) {
printf("%d", left[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
if(i == 16) {
printf("right :");
for(int j = 0; j< 32; j++) {
printf("%d", right[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
}
}
for(int j = 0; j< 32; j++) {
temp3[j] = right[j];
temp3[j + 32] = left[j];
}
printf("temp3 :");
for(int j = 0; j< 64; j++) {
printf("%d", temp3[j]);
if((j + 1) % 8 == 0) printf(" ");
}printf("\n");
replace(temp3, c, IP_1, 64);
return;
}
int main() {
int m[64] = {0, 0, 1, 1, 0, 0, 0, 0,
0, 0, 1, 1, 0, 0, 0, 1,
0, 0, 1, 1, 0, 0, 1, 0,
0, 0, 1, 1, 0, 0, 1, 1,
0, 0, 1, 1, 0, 1, 0, 0,
0, 0, 1, 1, 0, 1, 0, 1,
0, 0, 1, 1, 0, 1, 1, 0,
0, 0, 1, 1, 0, 1, 1, 1};
int k[64] = {0, 0, 1, 1, 0, 0, 0, 1,
0, 0, 1, 1, 0, 0, 1, 0,
0, 0, 1, 1, 0, 0, 1, 1,
0, 0, 1, 1, 0, 1, 0, 0,
0, 0, 1, 1, 0, 1, 0, 1,
0, 0, 1, 1, 0, 1, 1, 0,
0, 0, 1, 1, 0, 1, 1, 1,
0, 0, 1, 1, 1, 0, 0, 0};
int c[64] = {0};
DES(m, k, c);
return 0;
} 
DES是密码学实验里最简单的，数学公式最少的，核心就是这几张图，看着图就能自己实现DES算法。我自己的代码可以说是稀碎，但是确实是实现了
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分享题目：密码学实验DES的C语言实现-创新互联
标题来源：http://myzitong.com/article/cesdoc.html