DES加密算法C++實現
#include <stdlib.h>include <stdio.h>
include <string.h>
define ENCRYPT 1
define DECRYPT 0
static void printHex ( char cmd, int len ); static void printArray ( const char In, int len );
static void F_func ( bool In[32], const bool Ki[48] ); // f函數 static void S_func ( bool Out[32], const bool In[48] ); // S盒代替
static void Transform ( bool Out, bool In, const char Table, int len ); // 變換 static void Xor ( bool InA, const bool InB, int len ); // 異或 static void RotateL ( bool In, int len, int loop ); // 循環左移 static void ByteToBit ( bool Out, const char In, int bits ); // 字節組轉換成位組 static void BitToByte ( char Out, const bool In, int bits ); // 位組轉換成字節組
// 16位子密鑰 static bool SubKey[16][48];
// 64位經過PC1轉換為56位 (PC-1) const static char PC1_Table[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 };
// 左移 const static char LOOP_Table[16] = { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
// 排列選擇 2 (PC-2) const static char PC2_Table[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 };
// Ri_1（32位）經過變換E后膨脹為48位 (E) void F_func static const char E_Table[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 };
// 8個4比特合并為32比特的排列 P const static char P_Table[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, };
// 經過S盒 S-boxes const static char S_Box[8][4][16] = { { // S1 { 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 } }, { // S2 { 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 } }, { // S3 { 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 } }, { // S4 { 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, 4 }, { 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 } }, { // S5 { 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 } }, { // S6 { 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 } }, { // S7 { 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 } }, { // S8 { 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 } } };
// 初始排列 (IP) const static char IP_Table[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 };
// L16與R16合并后經過IP_1的最終排列 (IP**-1) const static char IPR_Table[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 };
void Des_SetKey ( const char Key[8] ); //生成子密鑰 void Des_Run ( char Out[8], char In[8], bool Type ); //DES算法
void main ( int argc, char *argv[] ) { char key[12]={1,2,3,4,5,6,7,8}; char str[12]="Hello"; char str2[12];
//printArray( PC2_Table, sizeof(PC2_Table)/sizeof(PC2_Table[0]) ); printf ( "Before encrypting: " ); puts ( str ); Des_SetKey ( key ); memset ( str2, 0, sizeof ( str2 ) ); Des_Run ( str2, str, ENCRYPT ); printf ( "After encrypting: " ); printHex ( str2, 8 ); memset ( str, 0, sizeof ( str ) ); printf ( "After decrypting: " ); Des_Run ( str, str2, DECRYPT ); puts ( str );}
void Des_SetKey ( const char Key[8] ) { int i; static bool K[64], KL = &K[0], KR = &K[28];
ByteToBit ( K, Key, 64 ); //轉換為二進制 Transform ( K, K, PC1_Table, 56 ); //64比特的密鑰K，經過PC-1后，生成56比特的串。 //生成16個子密鑰 for ( i=0; i<16; i++ ) { //循環左移，合并 RotateL ( KL, 28, LOOP_Table[i] ); RotateL ( KR, 28, LOOP_Table[i] ); Transform ( SubKey[i], K, PC2_Table, 48 ); }}
void Des_Run ( char Out[8], char In[8], bool Type ) { int i; static bool M[64], tmp[32], Li = &M[0], Ri = &M[32];
//轉換為64位的數據塊 ByteToBit ( M, In, 64 ); //IP置換 （初始） Transform ( M, M, IP_Table, 64 ); //該比特串被分為32位的L0和32位的R0兩部分。 if ( Type == ENCRYPT ) { //16輪置換 for ( i=0; i<16; i++ ) { memcpy ( tmp, Ri, 32 ); // R[i] = L[i-1] xor f(R[i-1], K[i]) F_func ( Ri, SubKey[i] ); // 2.4.6 Exclusive-or the resulting value with L[i-1]. // R[I]=P XOR L[I-1] Xor ( Ri, Li, 32 ); // L[i] = R[i-1] memcpy ( Li, tmp, 32 ); } } else { // 如果解密則反轉子密鑰順序 for ( i=15; i>=0; i-- ) { memcpy ( tmp, Li, 32 ); F_func ( Li, SubKey[i] ); Xor ( Li, Ri, 32 ); memcpy ( Ri, tmp, 32 ); } } //R16與L16合并成64位的比特串。R16一定要排在L16前面。R16與L16合并后成的比特串，經過置換IP-1后所得的比特串就是密文。 Transform ( M, M, IPR_Table, 64 ); BitToByte ( Out, M, 64 );}
//將32比特的輸入再轉化為32比特的輸出 void F_func ( bool In[32], const bool Ki[48] ) { static bool MR[48];
//輸入Ri-1(32比特)經過變換E后，膨脹為48比特 Transform ( MR, In, E_Table, 48 ); //異或 Xor ( MR, Ki, 48 ); //膨脹后的比特串分為8組，每組6比特。各組經過各自的S盒后，又變為4比特(具體過程見后)，合并后又成為32比特。 S_func ( In, MR ); //該32比特經過P變換后，輸出的比特串才是32比特的f (Ri-1,Ki)。 Transform ( In, In, P_Table, 32 );}
void S_func ( bool Out[32], const bool In[48] ) { char j,m,n;
//膨脹后的比特串分為8組，每組6比特。 for ( j=0; j<8; j++,In+=6,Out+=4 ) { //在其輸入In[0],In[1],In[2],In[3],In[4],In[5]中，計算出m=In[0]*2+In[5], n=In[4]+In[3]*2+In[2]*4+In[1]*8，再從Sj表中查出m行，n列的值Smn。將Smn化為二進制，即得Si盒的輸出。 m = ( In[0]<<1 ) + In[5]; n = ( In[1]<<3 ) + ( In[2]<<2 ) + ( In[3]<<1 ) + In[4]; ByteToBit ( Out, &S_Box[ ( int ) j][ ( int ) m][ ( int ) n], 4 ); }}
// 打印指定位置指定長度HEX值 static void printHex ( char *cmd, int len ) { int i;
for ( i=0; i<len; i++ ) { printf ( "[%02X]", ( unsigned char ) cmd[i] ); } printf ( "\n" );}
// 打印數組測試用 static void printArray ( const char *In, int len ) { int i; char tmp[256];
memset ( tmp, 0, sizeof ( tmp ) ); for ( i=0; i<len; i++ ) { tmp[ ( int ) In[i]]=In[i]; } for ( i=0; i<len; i++ ) { printf ( "[%02d]", ( unsigned char ) tmp[i] ); } printf ( "\n" );}
void Transform ( bool Out, bool In, const char *Table, int len ) { int i; static bool tmp[256];
for ( i=0; i<len; i++ ) { tmp[i] = In[ Table[i]-1 ]; } memcpy ( Out, tmp, len );}
void Xor ( bool InA, const bool InB, int len ) { int i;
for ( i=0; i<len; i++ ) { InA[i] ^= InB[i]; }}
void RotateL ( bool *In, int len, int loop ) { static bool tmp[256]; // Sample: loop=2 memcpy ( tmp, In, loop ); // In=12345678 tmp=12 memcpy ( In, In+loop, len-loop ); // In=345678 memcpy ( In+len-loop, tmp, loop ); // In=34567812 }
// Sample: // In = [0x01] // Out = [0x01] [0x00] [0x00] [0x00] [0x00] [0x00] [0x00] [0x00] void ByteToBit ( bool Out, const char In, int bits ) { int i;
for ( i=0; i<bits; i++ ) { // In[i]的第N位右移N位并和0x01按位"與"運算(N=1~8) Out[i] = ( In[i/8]>> ( i%8 ) ) & 1; }}
void BitToByte ( char Out, const bool In, int bits ) { int i;
memset ( Out, 0, ( bits+7 ) /8 ); for ( i=0; i<bits; i++ ) { Out[i/8] |= In[i]<< ( i%8 ); }}
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