基于C++的DES加密算法实现.docx
《基于C++的DES加密算法实现.docx》由会员分享，可在线阅读，更多相关《基于C++的DES加密算法实现.docx（27页珍藏版）》请在冰豆网上搜索。
基于C++的DES加密算法实现
今天偶尔想到数据加密技术，刚才简单讨论了一下MD5和SHA，这里顺便提一下双向加密的标准DES。
以前在一个宽带流媒体服务器项目中用到了DES加密，虽然使用环境相对单纯，但算法实现本身是具有普遍意义的。
下述程序是很久以前在RSA公司的网站找到的，效率很高，稳定性较好，便一直在实践中使用。
首先在头文件中定义一个DES类：
//des.h
#ifndef__DES_H
#define__DES_H
classDES{
public:
//Encrypt/decryptthedatain"data",accordingtothe"key".
//Callerisresponsibleforconfirmingthebuffersizeof"data"
//pointstois8*"blocks"bytes.
//Thedataencrypted/decryptedisstoredindata.
//Thereturncodeis1:
success,other:
failed.
intencrypt（unsignedcharkey[8],unsignedchar*data,intblocks=1）;
intdecrypt（unsignedcharkey[8],unsignedchar*data,intblocks=1）;
//Encrypt/decryptanysizedata,accordingtoaspecialmethod.
//Beforecallingyencrypt,copydatatoanewbufferwithsize
//calculatedbyextend.
intyencrypt（unsignedcharkey[8],unsignedchar*data,intsize）;
intydecrypt（unsignedcharkey[8],unsignedchar*in,intblocks,int*size=0）;
intextend（intsize）{return（size/8+1）*8;};
private:
voiddes（unsignedchar*in,unsignedchar*out,intblocks）;
voiddes_block（unsignedchar*in,unsignedchar*out）;
private:
unsignedlongKnL[32];
enumMode{ENCRYPT,DECRYPT};
voiddeskey（unsignedcharkey[8],Modemd）;
voidusekey（unsignedlong*）;
voidcookey（unsignedlong*）;
private:
voidscrunch（unsignedchar*,unsignedlong*）;
voidunscrun（unsignedlong*,unsignedchar*）;
voiddesfunc（unsignedlong*,unsignedlong*）;
private:
staticunsignedcharDf_Key[24];
staticunsignedshortbytebit[8];
staticunsignedlongbigbyte[24];
staticunsignedcharpc1[56];
staticunsignedchartotrot[16];
staticunsignedcharpc2[48];
staticunsignedlongSP1[64];
staticunsignedlongSP2[64];
staticunsignedlongSP3[64];
staticunsignedlongSP4[64];
staticunsignedlongSP5[64];
staticunsignedlongSP6[64];
staticunsignedlongSP7[64];
staticunsignedlongSP8[64];
};
#endif
而后，具体实现DES类：
//des.cpp
#include
#include"Sinodes.h"
intDES:
:
encrypt（unsignedcharkey[8],unsignedchar*data,intblocks）
{
if（（!
data）||（blocks<1））
return0;
deskey（key,ENCRYPT）;
des（data,data,blocks）;
return1;
};
intDES:
:
decrypt（unsignedcharkey[8],unsignedchar*data,intblocks）
{
if（（!
data）||（blocks<1））
return0;
deskey（key,DECRYPT）;
des（data,data,blocks）;
return1;
};
intDES:
:
yencrypt（unsignedcharkey[8],unsignedchar*data,intsize）
{
if（（!
data）||（size<1））
return0;
//Thelastcharofdataisbitwisecomplementedandfilledtherest
//buffer.Ifsizeis16,itwillextendto24,and17still24.
charlastChar=*（data+size-1）;
intblocks=size/8+1;
memset（data+size,~lastChar,blocks*8-size）;
deskey（key,ENCRYPT）;
returnencrypt（data,data,blocks）;
};
intDES:
:
ydecrypt（unsignedcharkey[8],unsignedchar*data,intblocks,int*size）
{
if（（!
data）||（blocks<1））
return0;
deskey（key,DECRYPT）;
if（!
decrypt（data,data,blocks））
return0;
if（size!
=0）
{
intpos=blocks*8-1;
charendChar=data[pos];
while（（pos>0）&&（data[pos]==endChar））
pos--;
if（data[pos]!
=~endChar）
return0;
*size=pos+1;
}
return1;
};
//-----------------------------------------------------------------------
//des
//Encrpts/Decrypts（accordingtothekeycurrentlyloadedintthe
//internalkeyregister）SOMEblocksofeightbytesataddress'in'
//intotheblockataddress'out'.Theycanbethesame.
//
//"in"
//"out"
//"block"Numberofblocks.
//-----------------------------------------------------------------------
voidDES:
:
des（unsignedchar*in,unsignedchar*out,intblocks）
{
for（inti=0;ides_block（in,out）;
};
//-----------------------------------------------------------------------
//des_block
//Encrpts/Decrypts（accordingtothekeycurrentlyloadedintthe
//internalkeyregister）oneblockofeightbytesataddress'in'
//intotheblockataddress'out'.Theycanbethesame.
//
//"in"
//"out"
//-----------------------------------------------------------------------
voidDES:
:
des_block（unsignedchar*in,unsignedchar*out）
{
unsignedlongwork[2];
scrunch（in,work）;
desfunc（work,KnL）;
unscrun（work,out）;
};
//----------------------------------------------------------------------
//deskey
//Setstheinternalkeyregister（KnR）accordingtothehexadecimal
//keycontainedinthe8bytesofhexkey,accordingtotheDES,
//forencryptionordecrytionaccordingtoMODE
//
//"key"isthe64bitskey.
//"md"meansencryptionordecryption.
//----------------------------------------------------------------------
voidDES:
:
deskey（unsignedcharkey[8],Modemd）
{
registerintii,j,l,m,n;
unsignedcharpc1m[56],pcr[56];
unsignedlongkn[32];
for（j=0;j<56;j++）{
l=pc1[j];
m=l&07;
pc1m[j]=（key[l>>3]&bytebit[m]）?
1:
0;
}
for（ii=0;ii<16;ii++）{
if（md==DECRYP）m=（15-ii）<<1;
elsem=ii<<1;
n=m+1;
kn[m]=kn[n]=0L;
for（j=0;j<28;j++）{
l=j+totrot[ii];
if（l<28）pcr[j]=pc1m[l];
elsepcr[j]=pc1m[l-28];
}
for（j=28;j<56;j++）{
l=j+totrot[ii];
if（l<56）pcr[j]=pc1m[l];
elsepcr[j]=pc1m[l-28];
}
for（j=0;j<24;j++）{
if（pcr[pc2[j]]）kn[m]|=bigbyte[j];
if（pcr[pc2[j+24]]）kn[n]|=bigbyte[j];
}
}
cookey（kn）;
return;
};
//----------------------------------------------------------------------
//cookey
//Onlycalledbydeskey.
//-----------------------------------------------------------------------
voidDES:
:
cookey（registerunsignedlong*raw1）
{
registerunsignedlong*cook,*raw0;
unsignedlongdough[32];
registerinti;
cook=dough;
for（i=0;i<16;i++,raw1++）{
raw0=raw1++;
*cook=（*raw0&0x00fc0000L）<<6;
*cook|=（*raw0&0x00000fc0L）<<10;
*cook|=（*raw1&0x00fc0000L）>>10;
*cook++|=（*raw1&0x00000fc0L）>>6;
*cook=（*raw0&0x0003f000L）<<12;
*cook|=（*raw0&0x0000003fL）<<16;
*cook|=（*raw1&0x0003f000L）>>4;
*cook++|=（*raw1&0x0000003fL）;
}
usekey（dough）;
return;
};
//----------------------------------------------------------------------
//usekey
//Onlycalledbycookey.
//Loadstheinteralkeyregisterwiththedataincookedkey.
//-----------------------------------------------------------------------
voidDES:
:
usekey（registerunsignedlong*from）
{
registerunsignedlong*to,*endp;
to=KnL,endp=&KnL[32];
while（toreturn;
};
voidDES:
:
scrunch（registerunsignedchar*outof,registerunsignedlong*into）
{
*into=（*outof++&0xffL）<<24;
*into|=（*outof++&0xffL）<<16;
*into|=（*outof++&0xffL）<<8;
*into++|=（*outof++&0xffL）;
*into=（*outof++&0xffL）<<24;
*into|=（*outof++&0xffL）<<16;
*into|=（*outof++&0xffL）<<8;
*into|=（*outof&0xffL）;
return;
};
voidDES:
:
unscrun（registerunsignedlong*outof,registerunsignedchar*into）
{
*into++=（*outof>>24）&0xffL;
*into++=（*outof>>16）&0xffL;
*into++=（*outof>>8）&0xffL;
*into++=*outof++&0xffL;
*into++=（*outof>>24）&0xffL;
*into++=（*outof>>16）&0xffL;
*into++=（*outof>>8）&0xffL;
*into=*outof&0xffL;
return;
};
voidDES:
:
desfunc（registerunsignedlong*block,registerunsignedlong*keys）
{
registerunsignedlongfval,work,right,leftt;
registerintround;
leftt=block[0];
right=block[1];
work=（（leftt>>4）^right）&0x0f0f0f0fL;
right^=work;
leftt^=（work<<4）;
work=（（leftt>>16）^right）&0x0000ffffL;
right^=work;
leftt^=（work<<16）;
work=（（right>>2）^leftt）&0x33333333L;
leftt^=work;
right^=（work<<2）;
work=（（right>>8）^leftt）&0x00ff00ffL;
leftt^=work;
right^=（work<<8）;
right=（（right<<1）|（（right>>31）&1L））&0xffffffffL;
work=（leftt^right）&0xaaaaaaaaL;
leftt^=work;
right^=work;
leftt=（（leftt<<1）|（（leftt>>31）&1L））&0xffffffffL;
for（round=0;round<8;round++）{
work=（right<<28）|（right>>4）;
work^=*keys++;
fval=SP7[work&0x3fL];
fval|=SP5[（work>>8）&0x3fL];
fval|=SP3[（work>>16）&0x3fL];
fval|=SP1[（work>>24）&0x3fL];
work=right^*keys++;
fval|=SP8[work&0x3fL];
fval|=SP6[（work>>8）&0x3fL];
fval|=SP4[（work>>16）&0x3fL];
fval|=SP2[（work>>24）&0x3fL];
leftt^=fval;
work=（leftt<<28）|（leftt>>4）;
work^=*keys++;
fval=SP7[work&0x3fL];
fval|=SP5[（work>>8）&0x3fL];
fval|=SP3[（work>>16）&0x3fL];
fval|=SP1[（work>>24）&0x3fL];
work=leftt^*keys++;
fval|=SP8[work&0x3fL];
fval|=SP6[（work>>8）&0x3fL];
fval|=SP4[（work>>16）&0x3fL];
fval|=SP2[（work>>24）&0x3fL];
right^=fval;
}
right=（right<<31）|（right>>1）;
work=（leftt^right）&0xaaaaaaaaL;
leftt^=work;
right^=work;
leftt=（leftt<<31）|（leftt>>1）;
work=（（leftt>>8）^right）&0x00ff00ffL;
right^=work;
leftt^=（work<<8）;
work=（（leftt>>2）^right）&0x33333333L;
right^=work;
leftt^=（work<<2）;
work=（（right>>16）^leftt）&0x0000ffffL;
leftt^=work;
right^=（work<<16）;
work=（（right>>4）^leftt）&0x0f0f0f0fL;
leftt^=work;
right^=（work<<4）;
*block++=right;
*block=leftt;
return;
};
//-----------------------------------------------------------------------
//Initialofstaticdatamembers.Thesedatawillbeusedbyallthe
//instancesofclass,andcannotbechanged.
//-----------------------------------------------------------------------
unsignedcharDES:
:
Df_Key[24]={
0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef,
0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10,
0x89,0xab,0xcd,0xef,0x01,0x23,0x45,0x67};
unsignedshortDES:
:
bytebit[8]={
0200,0100,040,020,010,04,02,01};
unsignedlongDES:
:
bigbyte[24]={
0x800000L,0x400000L,
升级会员 