C++简单数据加密算法实现加密和解密的代码

工作闲暇时间，把写内容过程中较好的内容珍藏起来，下面的资料是关于C++简单数据加密算法实现加密和解密的内容，应该是对小伙伴有用。

This is a program for Encryption and Decryption
This program uses the Simple Data Encryption Standard (SDES) Algorithm.
This Algo takes 8-bits of plaintext at a time and produces 8-bits of ciphertext.
It uses 10-bits of key for Encryption and Decryption.

Developed by : Vivek Kumar (vivek_kumar_bt@yahoo.co.in)

Created on : 31 March 2005
Last Modified on : 10 April 2005

Any sort of suggetions/comments are most welcome at vivek_kumar_bt@yahoo.co.in

#include<iostream.h>
#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<stdlib.h>
#include<assert.h>
void menuEn();
void menuDe();
int DoEnDe(int);

class SDES
{
private:
char KEY[11],K1[9],K2[9],IPOutput[9],InvIPOutput[9];
char F1Output[9],F2Output[9];
char INPUT_BIT[9],OUTPUT_BIT[9];

public:
unsigned char INPUT,OUTPUT;

~SDES();
void GenerateKeys();
void conv_to_bits(unsigned char );
void DES_Encryption(unsigned char );
void DES_Decryption(unsigned char );
void SDES::GetChar();
};
{
int i;
{
printf("nInValid Key-Length %s %d",key,strlen(key));
getch();
exit(1);
}
{
KEY[i]=key[i];
}
KEY[10]='0';

}

void SDES::GenerateKeys()
{
int i;

for (i=0;i<10;i++)
P10_OP[i]=KEY[P10[i]-1];

P10_OP[10]='0';

for (i=0;i<5;i++)
{
P10LEFT[i]=P10_OP[i];
P10RIGHT[i]=P10_OP[i+5];
}
P10LEFT[5]='0';
P10RIGHT[5]='0';

pl=new char[6];
pr=new char[6];

pl=Left_Shift(P10LEFT,1);
pr=Left_Shift(P10RIGHT,1);

for (i=0;i<5;i++)
{
plpr[i]=pl[i];
plpr[i+5]=pr[i];
}
plpr[10]='0';

for (i=0;i<8;i++)
K1[i]=plpr[P8[i]-1];

pl1=Left_Shift(pl,2);
pr1=Left_Shift(pr,2);

for (i=0;i<5;i++)
{
plpr[i]=pl1[i];
plpr[i+5]=pr1[i];
}
plpr[10]='0';

for (i=0;i<8;i++)
{
K2[i]=plpr[P8[i]-1];
}

}

{
int length=strlen(bs);

char_ptr = new char[length +1];
str=new char[length+1];
char_ptr=bs;

int i,j;
for (j=0;j<n;j++)
{
firstbit=char_ptr[0];

for (i=0;i<length-1;i++)
{
str[i]=char_ptr[i+1];
}
str[length-1]=firstbit;
char_ptr[length]='0';
char_ptr=str;
}
char_ptr[length]='0';
return(str);
}

void SDES::conv_to_bits(unsigned char ch)
{
int i,bit;
INPUT_BIT[8]='0';
for (i=7;i>=0;i--)
{
bit=ch%2;
ch=ch/2;

if (bit!=0)
INPUT_BIT[i]='1';
else
INPUT_BIT[i]='0';
}

}

{
int IPArray[8]={2,6,3,1,4,8,5,7};
int i;
IPOutput[8]='0';
for (i=0;i<8;i++)
{
IPOutput[i]=input[IPArray[i]-1];
}
}

{
int InvIPArray[8]={4,1,3,5,7,2,8,6};
int i;
InvIPOutput[8]='0';
for (i=0;i<8;i++)
{
InvIPOutput[i]=input[InvIPArray[i]-1];
}
}

void SDES::DES_Encryption(unsigned char input)
{
char LIP[5],RIP[5],L1[5],R1[5];
int i;

INPUT=input;

printf("nEncrpyting.........");

for (i=0;i<4;i++)
{
LIP[i]=IPOutput[i];
RIP[i]=IPOutput[i+4];
}
LIP[4]='0';
RIP[4]='0';

Function_F(LIP,RIP,1);

for (i=0;i<4;i++)
{
L1[i]=F1Output[i];
R1[i]=F1Output[4+i];
}
L1[4]='0';
R1[4]='0';

Function_F(R1,L1,2);

GetChar();
}

Here IP, InvIP, E/P, SBOX1 and SBOX2 are same
But Function_F first operats on sub-key K2 and
void SDES::DES_Decryption(unsigned char input)
{
char LIP[5],RIP[5],L1[5],R1[5];
int i;

INPUT=input;
conv_to_bits(INPUT);

printf("nDecrpyting.........");

for (i=0;i<4;i++)
{
LIP[i]=IPOutput[i];
RIP[i]=IPOutput[i+4];
}
LIP[4]='0';
RIP[4]='0';

Function_F(LIP,RIP,2);

for (i=0;i<4;i++)
{
L1[i]=F1Output[i];
R1[i]=F1Output[4+i];
}
L1[4]='0';
R1[4]='0';

Function_F(R1,L1,1);
InvIP(F1Output);
GetChar();
}

{
int i;
char SBOX_Output[5];
char P4_Output[5];
char fk_Output[5];
char Main_Output[9];

for (i=0;i<8;i++)
{
E_POutput[i]=rinput[E_P[i]-1];
}
E_POutput[8]='0';

EXOR_Output=EX_OR(E_POutput,key);

LEXOR=new char[strlen(EXOR_Output)/2+1];
REXOR=new char[strlen(EXOR_Output)/2+1];

for (i=0;i<strlen(EXOR_Output)/2;i++)
{
LEXOR[i]=EXOR_Output[i];
REXOR[i]=EXOR_Output[i+4];
}
LEXOR[4]=REXOR[4]='0';

SBOX0_Output=SBOX0(LEXOR);

SBOX1_Output=SBOX1(REXOR);

for (i=0;i<2;i++)
{
SBOX_Output[i]=SBOX0_Output[i];
SBOX_Output[i+2]=SBOX1_Output[i];
}
SBOX_Output[4]='0';

for (i=0;i<4;i++)
{
P4_Output[i]=SBOX_Output[P4[i]-1];
}
P4_Output[4]='0';

for (i=0;i<4;i++)
{
if (P4_Output[i]==linput[i])
fk_Output[i]='0';
else
fk_Output[i]='1';
}
fk_Output[4]='0';

for (i=0;i<4;i++)
{
Main_Output[i]=fk_Output[i];
Main_Output[i+4]=rinput[i];
}
Main_Output[8]='0';
strcpy(F1Output,Main_Output);
}

depending on the parameter k.
{
int i,klen;

output=new char[strlen(ep)+1];
key=new char[strlen(K1)+1];
if (k==1)
{
strcpy(key,K1);
} else
{
if (k==2)
{
strcpy(key,K2);
} else
{
printf("nnWrong Choice in the key parameter(1/2)");
getch();
exit(1);
}
}
klen=strlen(K1);
if (strlen(ep)!=klen)
{
printf("ninput=%d is not equal to K=%d",strlen(ep),klen);
printf("nnError in the Output of E/P (Length)..Press any key");
getch();
exit(1);
}
for (i=0;i<strlen(ep);i++)
{
if (ep[i]==key[i])
output[i]='0';
else
output[i]='1';
}
output[strlen(ep)]='0';
return(output);
}

{
3,2,1,0,
0,2,1,3,
3,1,3,2
};

char lrow[3],lcol[3];
int i,lr,lc,b;

SO=new char[3];

lrow[0]=l[0];
lrow[1]=l[3];
lcol[0]=l[1];
lcol[1]=l[2];

lrow[2]='0';
lcol[2]='0';

for (i=0;i<4;i++)
{
if (strcmp(lrow,bits[i])==0)
lr=i;
if (strcmp(lcol,bits[i])==0)
lc=i;
}
b=S0[lr][lc];
for (i=0;i<3;i++)
SO[i]=bits[b][i];
SO[3]='0';
return(SO);
}
{
2,0,1,3,
3,0,1,0,
2,1,0,3
};

char lrow[3],lcol[3];
int i,lr,lc,b;

SO=new char[3];

lrow[0]=l[0];
lrow[1]=l[3];
lcol[0]=l[1];
lcol[1]=l[2];

lrow[2]='0';
lcol[2]='0';

for (i=0;i<4;i++)
{
if (strcmp(lrow,bits[i])==0)
lr=i;
if (strcmp(lcol,bits[i])==0)
lc=i;
}
b=S0[lr][lc];
for (i=0;i<3;i++)
SO[i]=bits[b][i];

SO[3]='0';
return(SO);
}

void SDES::GetChar()
{
int i,j,in;
unsigned char ch=0;
bs=new char[9];
bs=InvIPOutput;
if (strlen(bs)>8)
{
printf("nWRONG LENGTH STRING");
exit(0);
}
for (i=0;i<8;i++)
{
if (bs[i]=='1')
{
in=1;
for (j=1;j<8-i;j++)
{
}
ch=ch+in;
}
}
OUTPUT=ch;
}

SDES::~SDES()
{
}

void main(void)
{
unsigned char ch,ch1;
int i,n=10,choice;

while (1)
{
key = new char[11];
sfname = new char[20];
tfname = new char[20];
mainmenu(&choice);
fflush(stdin);
switch (choice)
{
case 1:
menuEn();
DoEnDe(choice);
break;
case 2:

3ff7
menuDe();
DoEnDe(choice);
break;
case 3:
exit(0);
default:
printf("nWrong Choice Enter againnPress any key to return to Main Menu..");
getch();
break;
}
}
}

{
printf("nWhat do you want to do..");
printf("n1. Encryption");
printf("n2. Decryption");
printf("n3. Exit");
printf("nnEnter the choice? ");
scanf("%d",c);
}
void menuEn()
{
sfname=new char[20];
tfname=new char[20];
key=new char[11];
printf("nEncryption Menunn");
printf("nEnter the filename to be Encrypted: ");
gets(sfname);
printf("nEnter the Target file name: ");
gets(tfname);
printf("nEnter the 10-bits KEY: ");
gets(key);
printf("nnNotedown this key, as same key is used for Decryption");
}

void menuDe()
{
sfname=new char[20];
tfname=new char[20];
key=new char[11];
printf("nDecryption Menunn");
printf("nEnter the filename to be Decrypted: ");
gets(sfname);
printf("nEnter the Target file name: ");
gets(tfname);
printf("nEnter the 10-bits KEY: ");
gets(key);
}

int DoEnDe(int c)
{
SDES S(key);
int i,n;
unsigned char ch;
fp=fopen(tfname,"w");
ft=fopen(sfname,"r");
if (fp==NULL)
{
printf("nTarget File not opened SORRY");
getch();
fclose(fp);
return(0);
}
if (ft==NULL)
{
printf("nSource File not opened SORRY");
getch();
fclose(ft);
return(0);
}
while (fread(&ch,1,1,ft)==1)
{
S.OUTPUT=ch;

for (i=0;i<n;i++)
{
if (c==1)
S.DES_Encryption(S.OUTPUT);
if (c==2)
S.DES_Decryption(S.OUTPUT);
}
fwrite(&S.OUTPUT,1,1,fp);
}
printf("nCompleted!!!!!");
getch();
fclose(fp);
fclose(ft);
return(1);
}