package text; import java.util.Scanner; public class text { public static String myrc4(String aInput,String aKey){ int[] iS = new int[256]; byte[] iK = new byte[256]; for(int i = 0;i<256;i++){ iS[i] = i; } for(int i = 0;i<256;i++){ iK[i] = (byte)aKey.charAt(i%aKey.length()); } int j = 0; for(int i = 0;i < 256;i++){ j = (j + iS[i] + iK[i]) % 256; int temp = iS[i]; iS[i] = iS[j]; iS[j] = temp; } j =0; int i = 0; char[] iInputChar = aInput.toCharArray(); char[] iOutputChar = new char[iInputChar.length]; for(int x = 0;x < aInput.length();x++){ i = (i+1) % 256; j = (j+iS[i]) % 256; int temp = iS[i]; iS[i] = iS[j]; iS[j] = temp; int t = (iS[i] + iS[j] % 256) % 256; int iY = iS[t]; char iCY = (char)iY; iOutputChar[x] = (char) (iInputChar[x] ^ iCY); } return new String(iOutputChar); } public static void main(String[] args){ String str1 = myrc4("20200809030229徐仕华","jkhh"); System.out.println(str1); String str2 = myrc4(str1,"jkhh"); System.out.println(str2); } }注释每一句代码

代码注释如下：

package text;

import java.util.Scanner;

public class text {

    // 自定义RC4加解密算法
    public static String myrc4(String aInput, String aKey) {
        int[] iS = new int[256];
        byte[] iK = new byte[256];

        // 初始化 iS 数组
        for(int i = 0; i < 256; i++) {
            iS[i] = i;
        }

        // 初始化 iK 数组
        for(int i = 0; i < 256; i++) {
            iK[i] = (byte)aKey.charAt(i % aKey.length());
        }

        // 生成伪随机数流
        int j = 0;
        for(int i = 0; i < 256; i++) {
            j = (j + iS[i] + iK[i]) % 256;
            int temp = iS[i];
            iS[i] = iS[j];
            iS[j] = temp;
        }

        // 加解密
        j = 0;
        int i = 0;
        char[] iInputChar = aInput.toCharArray();
        char[] iOutputChar = new char[iInputChar.length];
        for(int x = 0; x < aInput.length(); x++) {
            i = (i + 1) % 256;
            j = (j + iS[i]) % 256;
            int temp = iS[i];
            iS[i] = iS[j];
            iS[j] = temp;
            int t = (iS[i] + iS[j] % 256) % 256;
            int iY = iS[t];
            char iCY = (char)iY;
            iOutputChar[x] = (char)(iInputChar[x] ^ iCY);
        }

        // 返回加解密结果
        return new String(iOutputChar);
    }

    // 测试主函数
    public static void main(String[] args) {
        String str1 = myrc4("20200809030229徐仕华", "jkhh"); // 对字符串进行加密
        System.out.println(str1);
        String str2 = myrc4(str1, "jkhh"); // 对加密后的字符串进行解密
        System.out.println(str2);
    }
}