我怎样才能翻译printf（“％c”，M）;我的DES实现从C到Java？

I'm a German student and for computer classes I need to implement the DES-encryption in Java (by myself, not by using the Java-API) and explain it in detail. I didn't find any Java-code-examples using google, however I did find an easy implementation in C. (I do not know C, I know a little C++, but not that well, pointer still get me now and then.)

我是德国学生,对于计算机类,我需要用Java实现DES加密(我自己,而不是使用Java-API)并详细解释。我没有找到任何使用谷歌的Java代码示例,但我确实在C中找到了一个简单的实现。(我不知道C,我知道一点点C ++,但不是那么好,指针仍然偶尔得到我。 )

So I tried simply converting the code from C to Java, which did work out about halfway, however I'm having a problem with the last part, especially with the example using:

所以我试着简单地将代码从C转换为Java,这在大约中途完成了,但是我在最后一部分遇到了问题,特别是使用的示例:

printf("%c",M);

Which, from what Google told me, seems to be converting numbers(Integer) to ASCII-Characters, but I'm not really sure. My Code seems to be working until that last part, so I would be thankful for anyone that can give me fix/hint.

从Google告诉我的,似乎是将数字(整数)转换为ASCII字符,但我并不确定。我的代码似乎一直工作到最后一部分,所以我会感谢任何可以给我修复/提示的人。

My Code:

import java.util.Scanner;

public class DES {

    /**
     * @param args
     */
    public static void main(String[] args) {

        Scanner eingabe = new Scanner(System.in);

        int p, q, key2, fn, encryption_key, temp1 , temp2 ,
            t, s =0 , privatekey1=1, b=0 , passwort_s=0, klartext;
        int[] Cipher = new int [100];
        String passwort;

        System.out.println("Enter the value of p and q");

        p = eingabe.nextInt();
        q = eingabe.nextInt();

        System.out.println(p);
        System.out.println(q);

        key2= p*q;


        fn=(p-1)*(q-1);
        System.out.println("Enter Enryption key e: ");
        encryption_key = eingabe.nextInt();

        do {

            s=(privatekey1*encryption_key)%fn;
            privatekey1++; 

        } while (s!=1); 

        privatekey1=privatekey1-1;



        System.out.println("Public Key : "+ encryption_key + ","+ key2 );
        System.out.println("Private Key: "+ privatekey1 + "," +key2 );
        System.out.println("Enter Message: ");
        passwort= eingabe.next();
        for ( temp2 = 0; temp2 < passwort.length(); temp2++) 
        {
            t = passwort.charAt(temp2);
            passwort_s=1;
            for(temp1 =0 ; temp1< encryption_key ; temp1++){
                passwort_s= passwort_s*t%key2;
            }
            passwort_s= passwort_s%key2;
            System.out.println(passwort_s);
        }

        System.out.println("Enter cipher Text: ");
        for(temp1=0;temp1< passwort.length(); temp1++ )
        {
            Cipher[temp1]= eingabe.nextInt();
        }

        System.out.println("Plainttext: ");
        for(temp2 =0; temp2 < passwort.length(); temp2++);
        {
            klartext=1;

            for(temp1 =0; temp1 < privatekey1; temp1 ++){
                klartext=klartext*Cipher[temp2]%key2;
            }
            klartext=klartext%key2;
            System.out.println(klartext);
        }
    }
}

How can I convert the

我怎样才能转换

printf("%c",M);

to Java, and is this then a full DES implementation?

到Java,这是一个完整的DES实现吗?

4 个解决方案

#1

Its late and I'm tired but this isn't a DES implementation, is it?

它已经晚了我累了,但这不是DES实现,是吗?

It looks more like RSA.

它看起来更像RSA。

Yeah the link on your post is an asymmetrical cryptosystem. DES is symmetrical.

是的,你的帖子上的链接是一个不对称的密码系统。 DES是对称的。

#2

Or, more concisely:

或者,更简洁:

output.print((char)M);

This assumes M is a numeric value representing an ASCII character from 0-127 (or an ISO 8859-1 character from 0-255, or a Unicode character from 0-65535).

这假设M是一个数值,表示0-127的ASCII字符(或0-255的ISO 8859-1字符,或0-65535的Unicode字符)。

It also assumes output is a PrintWriter or PrintStream, one of which is System.out (a FileOutputStream is easily wrapped by a PrintOutputStream, or PrintWriter(new OutputStreamWriter)).

它还假设输出是PrintWriter或PrintStream,其中一个是System.out(FileOutputStream很容易被PrintOutputStream或PrintWriter(new OutputStreamWriter)包装)。

#3

Des is actually a fairly tough algotrithm to get your head around. I was about to blog about it but when I dug down. I couldn't break it down into pieces I was happy with.

Des实际上是一个相当艰难的算法,让你的头脑。我正要写博客,但是当我挖掘时。我无法把它分解成我满意的碎片。

Here is how very roughtly DES works.

以下是DES的工作方式。

Choose a 64bit key. (throw away 8bits)

选择64位密钥。 (丢掉8位)

For each 64bit block split in half

每个64位块分成两半

Do some xor based perumutation based on sub-keys genererated and do the same to the other half.

基于生成的子密钥进行一些基于xor的perumutation,并对另一半执行相同的操作。

Do some substitution.

做一些替代。

Do more permutatation

做更多的permutatation

to Decrypt run in reverse number.

解密以反向编号运行。

*this is a gross simplification.

*这是一个粗略的简化。

#4

this program is for RSA algorithm and not for DES. DES code is 8 times larger than RSA :)

此程序适用于RSA算法,不适用于DES。 DES代码比RSA大8倍:)

#1