应用密码学密码学_密码学中的围栏密码

以你之姓@ 2023-03-05 10:59 158阅读 0赞

应用密码学密码学

In **Rail Fence Cipher**, given a plain-text message and a numeric key then cipher/decipher the given text using the **Rail Fence algorithm**.

在**Rail Fence Cipher中** ，给定纯文本消息和数字键，然后使用**Rail Fence算法**对给定文本进行加密/解密。

The **rail fence cipher** is also called a **"zigzag cipher"** because we make a rectangle box and write plain text into it in a zigzag form. It is a form of transposition cipher that jumbles up the order of the letters of a message using a basic algorithm. It derives its name from how it is encrypted.

**铁路围栏密码**也称为**“之字形密码”，**因为我们制作了一个矩形框，并以之字形形式将纯文本写入其中。 它是一种转位密码，它使用一种基本算法来弄乱消息字母的顺序。 它从其加密方式获得其名称。

The **rail fence cipher** works by writing your plain text or message on alternate lines across the prail and then reading off each line or rows in turn by turn.

**围栏密码的**工作原理是，在遍历目录的交替行上书写纯文本或消息，然后依次轮流读取每行或每一行。

## 加密 **(**Encryption**)** ##

In a transposition cipher, the order of the alphabets is mixed up or we can say rearrange to obtain the cipher-text or encrypted text.

在换位密码中，字母的顺序混合在一起，或者我们可以说重新排列以获得密文或加密文本。

*  In the rail fence cipher, the plain-text is written as zigzag way as firstly go downward till the box is not end and diagonally on successive rails of an imaginary fence.
    
    在铁路围栏密码中，纯文本以锯齿形的方式书写，因为它首先向下走直到盒子没有尽头，并在假想的围栏的连续轨道上以对角线形式出现。
 *  When we reach the bottom rail, we simply traverse opposite moving diagonally, after reaching the top rail or top line, the direction is changed again. Thus the alphabets of the plain text are written in a zig-zag form.
    
    当我们到达底部轨道时，我们只需沿对角线移动相反的方向，到达顶部轨道或顶线后，方向便会再次改变。 因此，纯文本的字母以Z字形形式书写。
 *  When all the alphabet is fill in the rail then the individual's rows are combined together to give a ciphertext.
    
    当所有字母都填满后，个人的行将合并在一起以给出密文。

**Example:**

**例：**

The plaintext we have i.e **"defend the east wall"** having a key size or the size of the row is 3, we get the encryption method below,

我们使用明文，即**“保卫东墙”** ，其密钥大小或行的大小为3，我们得到以下加密方法，

![Rail Fence Cipher (1)][Rail Fence Cipher _1]

That at the end of the message we have inserted two **"X"s**. These are called nulls and act as placeholders. We do this to make the text fit into the rail so that there is the same number of letters on the top row as well as on the bottom row. Otherwise, it is not necessary, it makes the decryption process a bit easier if the text has this format.

在消息末尾，我们插入了两个**“ X”** 。 这些被称为null并充当占位符。 我们这样做是为了使文本适合轨道，从而使顶行和底行上的字母数相同。 否则，没有必要，如果文本具有这种格式，它会使解密过程更加容易。

And the cipher text became: **"dnetleedheswlxftaax"**.

密文变成： **“ dnetleedheswlxftaax”** 。

## 解密 **(**Decryption**)** ##

As we have studied earlier, the number of columns in rail fence cipher remains equal to the length of plain-text which we took. And the key remains the same as in encryption to the number of rails.

正如我们先前所研究的，围栏密码中的列数保持等于我们采用的纯文本长度。 密钥与加密轨数相同。

*  Hence, the Rail Fence matrix can be constructed likely. Once we have got the matrix we can find-out the places where plain texts should be placed using the same way as we doe in the encryption method of moving diagonally up and down alternatively to form text.
    
    因此，可以构建铁栅栏矩阵。 一旦获得矩阵，就可以使用与对角线上下交替移动以形成文本的加密方法相同的方式，找出应放置纯文本的位置。
 *  Then, we fill the cipher-text accordingly to row-wise. After filling the text, we traverse the matrix in the zig-zag form to get the original text or the plain text.
    
    然后，我们相应地按行填充密文。 填充文本后，我们以Z字形形式遍历矩阵以获取原始文本或纯文本。

**Example:**

**例：**

If we get the ciphertext **"TEKOOHRACIRMNREATANFTETYTGHH"**, it will be encrypted with a key size of 4.

如果我们获得密文**“ TEKOOHRACIRMNREATANFTETYTGHH”** ，它将使用密钥大小4进行加密。

We start by placing the **"T"** in the first square. You then dash the diagonal down places until you get back to the top line, and place the **"E"** here. Continuing to fill the rows you get the pattern below,

我们首先将**“ T”**放在第一个方块中。 然后，将对角线向下划线，直到回到顶部，然后在此处放置**“ E”** 。 继续填充行，您将获得以下模式，

![Rail Fence Cipher (2)][Rail Fence Cipher _2]

As we have a key size of 4 and the length of the message is 28 so we make like this and continues this till all the text does not fit into it.

因为我们的密钥大小为4，消息的长度为28，所以我们这样做，直到所有文本都无法容纳为止。

![Rail Fence Cipher (3)][Rail Fence Cipher _3]

Second stage in decryption process,

解密过程的第二阶段，

![Rail Fence Cipher (4)][Rail Fence Cipher _4]

Third stage in decryption process,

解密过程的第三阶段

![Rail Fence Cipher (5)][Rail Fence Cipher _5]

Forth and the final stage in decrption process,

在去毛刺过程的最后阶段，

Now, we read them as diagonally from top to bottom then bottom to top and we get the plain text or the original text i.e. **"THEY ARE ATTACKING FROM THE NORTH"**.

现在，我们从上到下然后从下到上以对角线形式阅读它们，然后得到纯文本或原始文本，即**“他们正从北方袭击”** 。

**Reference:** [Rail Fence Cipher][]

**参考：** [围栏密码][Rail Fence Cipher]

> 翻译自: [https://www.includehelp.com/cryptography/rail-fence-cipher.aspx][https_www.includehelp.com_cryptography_rail-fence-cipher.aspx]

应用密码学密码学

[Rail Fence Cipher _1]: https://www.includehelp.com/cryptography/Images/rail-fence-cipher-1.jpg
[Rail Fence Cipher _2]: /images/20230208/2d66d0bbe67d4e2cbd069993cf3064f2.png
[Rail Fence Cipher _3]: https://www.includehelp.com/cryptography/Images/rail-fence-cipher-3.jpg
[Rail Fence Cipher _4]: /images/20230208/c26c8a07e51f462493e1b321870afa51.png
[Rail Fence Cipher _5]: /images/20230208/041dc597deb9415ebd356cf7b9b54bc1.png
[Rail Fence Cipher]: https://crypto.interactive-maths.com/rail-fence-cipher.html
[https_www.includehelp.com_cryptography_rail-fence-cipher.aspx]: https://www.includehelp.com/cryptography/rail-fence-cipher.aspx