[英]Need help troubleshooting my VigenereCipher java code
Okay so I created this code last year for a class project and I remember it working correctly. 好的,我去年在一个班级项目中创建了此代码,我记得它可以正常工作。 I now need it to implement a text cipher but for some reason it does not work correctly.
我现在需要它来实现文本密码,但是由于某种原因它无法正常工作。 It will encrypt, but when I try to decrypt only the first two letters are correct.
它将加密,但是当我尝试解密时,仅前两个字母是正确的。 The rest of it is all wrong.
其余的一切都是错误的。 It is very simple, it is a command-line program where the first argument is whether it is encrypting(-e) or decrypting(-d), second argument is the key and third argument is the text you will encrypt.
这很简单,它是一个命令行程序,其中第一个参数是加密(-e)还是解密(-d),第二个参数是密钥,第三个参数是您要加密的文本。 It is similar to a caesar cipher except it takes each character as a reference when adding to each individual char in the string.
它与凯撒密码类似,不同之处在于,在将其添加到字符串中的每个字符时,它会将每个字符作为参考。 Can anyone tell me what is wrong, I do not understand why it does not work anymore and I need it for a project.
谁能告诉我哪里出了问题,我不明白为什么它不再起作用了,因此我需要一个项目。
import java.util.*;
public class VigenereCipher
{
public static void main(String[] args)
{
Scanner scan = new Scanner (System.in);
String key = "";
String ori = "";
String res = "";
if(!(args.length == 0))
{
if (args[0].equals("-e"))
{
key = args[1];
ori = args[2];
encrypt(ori, key);
System.out.println(encrypt(ori, key));
}
else if (args[0].equals("-d"))
{
key = args[1];
ori = args[2];
decrypt(ori, key);
System.out.println(decrypt(ori, key));
}
else
{
System.out.print("Usage: java VigenereCipher [-e,-d] key text");
}
}
}
static String encrypt(String text, final String key)
{
String res = "";
text = text.toUpperCase();
for (int i = 0, j = 0; i < text.length(); i++)
{
char c = text.charAt(i);
if (c < 'A' || c > 'Z') continue;
res += (char)((c + key.charAt(j) - 2 * 'A') % 26 + 'A');
j = ++j % key.length();
}
return res;
}
static String decrypt(String text, final String key)
{
String res = "";
text = text.toUpperCase();
for (int i = 0, j = 0; i < text.length(); i++)
{
char c = text.charAt(i);
if (c < 'A' || c > 'Z') continue;
res += (char) ((c - key.charAt(j) + 26) % 26 + 'A');
j = ++j % key.length();
}
return res;
}
}
You are supposed to be able to encrypt a string of text with a key then decrypt the output from the encryption using the same key for example: java VigenereCipher -e hello hello
will give me "UOCCI" as output but when I take that output and do java VigenereCipher -d hello UOCCI
it gives me "HE225" as my output and not "HELLO". 您应该能够使用密钥对文本字符串进行加密,然后使用相同的密钥对加密输出进行解密,例如:
java VigenereCipher -e hello hello
将给我“ UOCCI”作为输出,但是当我使用该输出时,做java VigenereCipher -d hello UOCCI
它给了我“ HE225”作为我的输出,而不是“ HELLO”。
You forgot that your key also needs to be in the same alphabet. 您忘记了密钥也需要使用相同的字母。 So if you supply a lowercase key your algorithm will fail.
因此,如果提供小写密钥,则算法将失败。
This will become abundantly clear when you split your algorithm in parts, eg I just went through: 当您将算法分为几部分时,这一点将变得非常清楚,例如,我刚刚经历过:
int im = c + key.charAt(j) - 2 * 'A';
res += (char)(im % 26 + 'A');
with my debugger and presto, the problem showed up. 用我的调试器和presto,问题出现了。
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