大神們幫忙解一下這串密碼，應該是四方或者二方密碼（我也不知道對不對）？

01-25

一個朋友寫給我的，困擾我好幾天了，跪請哥哥姐姐們幫幫忙
密鑰：right password

謝邀，基本可以確定，這是用四方密碼加密的消息。

關於四方密碼，具體鏈接如下：

四方密碼_百度百科。

四方密碼需要剔除一個字母，具體思路是遍歷字元串找出沒有出現的字母。先寫程序分析一下：

String msg = "YH HI JB ZA CN DH OE SK XB EM GG,EO LB EL GG IB OO JI IZ NY EA JB EP QR JB QK,HI JB GB ZM QH NB HT DS GR";
Set& set = new HashSet&();
for (int i = 0; i &< msg.length(); i++)
if (msg.charAt(i) != " ")
set.add(msg.charAt(i));
for (char j = "A"; j &<= "Z"; j++)
if (!set.contains(j))
System.out.println(j);

輸出如下：

也就是上述一個字母已經被剔除。

接下來是實現四方加密的代碼，分為三個類，一個加密表SquareGrid,一個加密器SquareCipher以及一個測試類。

加密表主要用於生成一個加密矩陣，給出兩個字元它能把它轉化成加密後的字元，同時給出加密後的字元它也能夠還原。加密器主要用於創建加密表實例同時執行加密解密方法。

public class SquareGrid {
private char[] g0;
private char[] g1;
private char[] g2;

private static final char[] a2z = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p",
"q", "r", "s", "t", "u", "v", "w", "x", "y", "z" };
private static final char[] A2Z = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P",
"Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
public void init(char c, String lts, String rbs) {
g0 = new char[25];
g1 = new char[25];
g2 = new char[25];
lts = lts.toUpperCase().replaceAll("[^A-Z]", "");
rbs = rbs.toUpperCase().replaceAll("[^A-Z]", "");

int j = 0;
for (int i = j; i &< a2z.length; i++) {
if (a2z[i] != c j &< 25) {
g0[j] = a2z[i];
j++;
}
}
char uC = (char) (c - 32);
occupy(g1, uC, lts);
occupy(g2, uC, rbs);

}
private static void occupy(char[] cs, char c, String s) {
int j = 0;
char temp;
for (int i = 0; i &< s.length(); i++) {
temp = s.charAt(i);
if (!contains(cs, temp) c != temp j &< cs.length) {
cs[j] = temp;
j++;
}

}
for (int i = 0; i &< A2Z.length; i++) {
if (!contains(cs, A2Z[i]) c != A2Z[i] j &< cs.length) {
cs[j] = A2Z[i];
j++;
}
}
}
private static boolean contains(char[] cs, char c) {
int i = 0;

while (i &< cs.length cs[i] != "") {
if (cs[i] == c)
return true;
i++;
}
return false;
}
public char[] encrypt(char c1, char c2) {
int i1 = 5, j1 = 5, i2 = 5, j2 = 5;
for (int i = 0; i &< 25; i++) {

if (g0[i] == c1) {
i1 = i / 5;
j1 = i % 5;
}
if (g0[i] == c2) {
i2 = i / 5;
j2 = i % 5;
}
}
if (i1 == 5 || i2 == 5)

return null;
char[] cs = new char[2];
cs[0] = g1[5 * i1 + j2];
cs[1] = g2[5 * i2 + j1];
return cs;
}
public char[] decrypt(char c1, char c2) {
int i1 = 5, j1 = 5, i2 = 5, j2 = 5;
for (int i = 0; i &< 25; i++) {
if (g1[i] == c1) {
i1 = i / 5;
j1 = i % 5;
}
if (g2[i] == c2) {
i2 = i / 5;
j2 = i % 5;
}
}
if (i1 == 5 || i2 == 5)
return null;
char[] cs = new char[2];
cs[0] = g0[5 * i1 + j2];
cs[1] = g0[5 * i2 + j1];
return cs;
}
@Override
public String toString() {
StringBuffer sb = new StringBuffer();
for (int i = 0; i &< 10; i++) {
if (i &< 5) {
for (int j = 0; j &< 10; j++) {
if (j &< 5)
sb.append(g0[5 * i + j]);
else
sb.append(g1[5 * i + j - 5]);
if (j != 9)
sb.append(",");
}
} else {
for (int j = 0; j &< 10; j++) {
if (j &< 5)
sb.append(g2[5 * (i - 5) + j]);
else
sb.append(g0[5 * (i - 5) + j - 5]);
if (j != 9)
sb.append(",");
}
}
sb.append("
");
}
return sb.toString();
}
}

//===============================================================

public class SquareCipher {
public static SquareGrid getGridInstance(String kickOut, String key1, String key2) {
SquareGrid grid = new SquareGrid();
kickOut = kickOut.toLowerCase().replaceAll("[^a-z]", "");
grid.init(kickOut.charAt(0), key1, key2);
return grid;
}
public static String encrypt(SquareGrid grid, String msg) {
if (msg == null || "".equals(msg))
return null;
msg = msg.toLowerCase().replaceAll("[^a-z]", "");
StringBuffer sb = new StringBuffer();
char[] temp;
int i = 0;
while (i + 1 &< msg.length()) {
temp = grid.encrypt(msg.charAt(i), msg.charAt(i + 1));
sb.append(temp);
sb.append(" ");
i += 2;
}
return sb.toString();
}
public static String decrypt(SquareGrid grid, String cipher) {
if (cipher == null || "".equals(cipher))
return null;
cipher = cipher.toUpperCase().replaceAll("[^A-Z]", "");
StringBuffer sb = new StringBuffer();
char[] temp;
int i = 0;
while (i + 1 &< cipher.length()) {
temp = grid.decrypt(cipher.charAt(i), cipher.charAt(i + 1));
sb.append(temp);
i += 2;
}
return sb.toString();
}
}

//============================================================

public static void main(String[] args) {
String msg = "YH HI JB ZA CN DH OE SK XB EM GG,EO LB EL GG IB OO JI IZ NY EA JB EP QR JB QK,HI JB GB ZM QH NB HT DS GR";
String[] msgs = msg.split(",");
Set& set = new HashSet&();
for (int i = 0; i &< msg.length(); i++)
if (msg.charAt(i) != " ")
set.add(msg.charAt(i));
for (char j = "A"; j &<= "Z"; j++)
if (!set.contains(j))
System.out.println(j);
SquareGrid grid = SquareCipher.getGridInstance("F", "right", "password");
System.out.println(grid);
// String cipher = SquareCipher.encrypt(grid, msg);
// System.out.println(cipher);
for (int i = 0; i &< msgs.length; i++)
System.out.println(SquareCipher.decrypt(grid, msgs[i]));
}

用四個可能被剔除的字母去嘗試，採用F的時候有如下結果：

wocongweishouguoxihuan

keniguanchuanlewozhenggeqingun

congciwurnnketidai

仔細讀吧，大概是：

我從未說過喜歡，可你貫穿了我整個青春，從此無可替代。

有一些不通順應該是因為舍掉了F的原因或者程序bug，我隱約感受到一段愛情，

加油！