📄 des.java
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//---------------------------------------------
//计算Ln和Rn
for(int i=1;i<=16;i++)
{
L[i]=new StringBuffer(32);
R[i]=new StringBuffer(32);
L[i]=R[i-1];
R[i]=xorfunction(L[i-1],Ffunction(R[i-1],k[i-1]));
//System.out.println("L"+i+":"+L[i]);
//System.out.println("R"+i+":"+R[i]);
}
//------------------------------------
//计算密文------------------------
int anti_displace[]={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};
StringBuffer Ciphertextno=new StringBuffer(64);
StringBuffer Ciphertextbinary=new StringBuffer(64);
StringBuffer Ciphertext=new StringBuffer(16);
Ciphertextno.append(R[16]);
Ciphertextno.append(L[16]);
for(int i=0;i<64;i++)
{
Ciphertextbinary.insert(i,Ciphertextno.charAt(anti_displace[i]-1));
}
//System.out.println(Ciphertextbinary);
//把二进制序列串转换为十六进制串
int j=0;
String substring=null,b=null;
Integer a;
int a1;
for(int i=0;i<16;i++)
{
substring=null;
b=null;
substring=Ciphertextbinary.substring(j,j+4); //四个四个取二进制串
a=Integer.valueOf(substring,2); //把二进制串转换为整型数
a1=a.intValue();
b=Integer.toHexString(a1); //把整型转换为十六进制的串
Ciphertext.append(b); //得到最后的十六进制串
j=j+4;
}
System.out.print("密文为：");
System.out.println(Ciphertext);
//----------以上为加密过程----------------------------------------
//------------------------------------------------------------------
return;
}
//--------------------------------------------------------
//----------------------解密------------------------------
public static void decodefunction()throws IOException
{
BufferedReader keyinCipher=new BufferedReader(new InputStreamReader(System.in));
System.out.println("对密文进行解密");
System.out.print("请输入密钥：");
String Cipher;
Cipher=keyinCipher.readLine(); //读入密钥
System.out.println();
int Cipherlength=Cipher.length();
if(Cipherlength!=16)
System.out.println("密钥位数不对");
BufferedReader keyinplain=new BufferedReader(new InputStreamReader(System.in));
System.out.print("请输入密文:");
String plaintext;
plaintext=keyinplain.readLine(); //读入密文
System.out.println();
int plaintextlength=plaintext.length();
if(plaintextlength!=16)
System.out.println("密文位数不对");
//String Cipher=new String("123abc1111111111");
//System.out.print("密钥为:");
//System.out.println(Cipher); //输出密钥
StringBuffer Cipher_code=new StringBuffer(64);
StringBuffer binarystr=new StringBuffer(4);
int Cipher_length,w;
Cipher_length=Cipher.length();
for(int i=0;i<Cipher_length;i++)
{
String chartostr=null,binarychar=null;
binarystr=null;
binarystr=new StringBuffer(4);
chartostr=String.valueOf(Cipher.charAt(i));
w=Integer.parseInt(chartostr,16); //把每一个字母转换为int
binarychar=Integer.toBinaryString(w);
binarystr.append(binarychar);
if(binarychar.length()<5)
{
for(int j=0;j<4-binarychar.length();j++)
{
binarystr.insert(0,0);
}
} //把密钥中的每一位变为四位
//的二进制字符串
Cipher_code.append(binarystr);
}
//System.out.println(Cipher_code); //输出密钥所对应的二进制码
//-----------------------------------------
//初始置换得到cn，dn
int displacec0[]={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};
int displaced0[]={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 move[]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
StringBuffer c0=new StringBuffer(28);
StringBuffer d0=new StringBuffer(28);
for(int i=0;i<28;i++)
{
c0.insert(i,Cipher_code.charAt(displacec0[i]-1));
d0.insert(i,Cipher_code.charAt(displaced0[i]-1));
}
StringBuffer c[]=new StringBuffer[16];
StringBuffer d[]=new StringBuffer[16];
c[0]=new StringBuffer(28);
d[0]=new StringBuffer(28);
c[0]=cndn(c0,move[0]);
d[0]=cndn(d0,move[0]);
for(int i=1;i<16;i++)
{
c[i]=new StringBuffer(28);
d[i]=new StringBuffer(28);
c[i]=cndn(c[i-1],move[i]);
d[i]=cndn(d[i-1],move[i]);
//System.out.println("c"+i+":"+c[i]);
//System.out.println("d"+i+":"+d[i]);
}
/*
for(int i=0;i<16;i++)
{
System.out.println(c[i]);
System.out.println(d[i]);
}
*/
//---------------------------------
//置换2：由cn，dn得到kn即k[]
int conbinition[]={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};
StringBuffer k[]=new StringBuffer[16];
for(int i=0;i<16;i++)
{
k[i]=new StringBuffer(48);
for(int j=0;j<48;j++)
{
if(conbinition[j]>28)
k[i].insert(j,d[i].charAt((conbinition[j]-1)%28));
else
k[i].insert(j,c[i].charAt(conbinition[j]-1));
}
//System.out.println("k"+i+k[i]);
}
//---------------------------
//把读入的密文变为64位编码
StringBuffer plaintext_code=new StringBuffer(64);
StringBuffer binarystr_plaintext=new StringBuffer(4);
int plaintext_length,w_plaintext;
plaintext_length=plaintext.length();
for(int i=0;i<plaintext_length;i++)
{
String chartostr_plaintext=null,binarychar_plaintext=null;
binarystr_plaintext=null;
binarystr_plaintext=new StringBuffer(4);
chartostr_plaintext=String.valueOf(plaintext.charAt(i));
w_plaintext=Integer.parseInt(chartostr_plaintext,16); //把每一个字母转换为int
binarychar_plaintext=Integer.toBinaryString(w_plaintext);
binarystr_plaintext.append(binarychar_plaintext);
if(binarychar_plaintext.length()<5)
{
for(int j=0;j<4-binarychar_plaintext.length();j++)
{
binarystr_plaintext.insert(0,0);
}
} //把密文中的每一位变为四位
//的二进制字符串
plaintext_code.append(binarystr_plaintext);
}
//System.out.println(plaintext_code);
//对密文进行处理
int replaceR16[]={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};
int replaceL16[]={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};
StringBuffer L[]=new StringBuffer[17];
StringBuffer R[]=new StringBuffer[17];
L[16]=new StringBuffer(32);
R[16]=new StringBuffer(32);
for(int i=0;i<32;i++)
{
L[16].insert(i,plaintext_code.charAt(replaceL16[i]-1));
R[16].insert(i,plaintext_code.charAt(replaceR16[i]-1));
}
//---------------------------------------------
//计算Ln和Rn
for(int i=15;i>=0;i--)
{
L[i]=new StringBuffer(32);
R[i]=new StringBuffer(32);
R[i]=L[i+1];
L[i]=xorfunction(R[i+1],Ffunction(L[i+1],k[i]));
//System.out.println("L"+i+":"+L[i]);
//System.out.println("R"+i+":"+R[i]);
}
//-----------------------------------
//逆初始变换求明文
int anti_displace[]={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};
StringBuffer Ciphertextno=new StringBuffer(64);
StringBuffer Ciphertextbinary=new StringBuffer(64);
StringBuffer Ciphertext=new StringBuffer(16);
Ciphertextno.append(L[0]);
Ciphertextno.append(R[0]);
for(int i=0;i<64;i++)
{
Ciphertextbinary.insert(i,Ciphertextno.charAt(anti_displace[i]-1));
}
System.out.println(Ciphertextbinary);
//把二进制序列串转换为十六进制串
int j=0;
String substring=null,b=null;
Integer a;
int a1;
for(int i=0;i<16;i++)
{
substring=null;
b=null;
substring=Ciphertextbinary.substring(j,j+4); //四个四个取二进制串
a=Integer.valueOf(substring,2); //把二进制串转换为整型数
a1=a.intValue();
b=Integer.toHexString(a1); //把整型转换为十六进制的串
Ciphertext.append(b); //得到最后的十六进制串
j=j+4;
}
System.out.print("明文为：");
System.out.println(Ciphertext);
return;
}
//-------------------主函数---------------------
public static void main(String args[])throws IOException
{
BufferedReader keyin2=new BufferedReader(new InputStreamReader(System.in));
System.out.println("请选择:");
System.out.println("\"1\":加密");
System.out.println("\"2\":解密");
System.out.println("\"3\":退出");
String choise;
choise=keyin2.readLine();
while(choise.compareTo("")==0)
{
System.out.println("不能为空，请选择！");
choise=keyin2.readLine();
}
char choisechar;
while(choise.compareTo("3")!=0)
{
choisechar=choise.charAt(0); //把输入的字符串转换为字符类型
switch(choisechar)
{
case '1': encodefunction();
//System.out.println("呵呵，成功");
System.out.println("请选择:");
System.out.println("\"1\":加密");
System.out.println("\"2\":解密");
System.out.println("\"3\":退出");
choise=keyin2.readLine();
break;
case '2': decodefunction();
System.out.println("请选择:");
System.out.println("\"1\":加密");
System.out.println("\"2\":解密");
System.out.println("\"3\":退出");
choise=keyin2.readLine();
break;
default: System.out.println("错误输入，请重试");
choise=keyin2.readLine();
break;
}
}
}
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