Cryptography can be defined as an art of encoding and decoding the patterns (in the form of messages).
密码术是一个非常简单的概念，涉及处理字符串(或文本)以使中间人无法理解的内容。它具有一种非常有效的方式来加密或解密来自其他方的文本。某些示例包括Caesar密码，Viginere密码，Columner密码，DES，AES，并且列表继续。要开发自定义密码算法，可以使用混合加密算法。
混合加密是密码学中的一个概念，它组合/合并一个/两个密码学算法以生成更有效的加密文本。
例子：
FibBil密码学算法
问题陈述：
程序通过计算Fibonacci系列，将Fibonacci系列的条款与每个纯文本字母相加，直到密钥的长度，以生成加密的文本。
算法：
对于加密：从用户那里获取输入的纯文本和密钥，反转纯文本并将纯文本与密钥连接起来，然后将字符串复制到数组中。复制后，将数组元素分为两部分，EvenArray和OddArray，其中数组的偶数索引将放置在EvenArray中，OddArray相同。开始生成最接近密钥j长度的斐波那契数列F(i)，使得c = i + j ，其中c是带有mod 26的密文。将所有c个元素附加到CipherString中，然后加密完成！ 。使用总结概念时，它是实施Caesar Cipher的重点。
解密：加密算法的副词
算法示例：
Input: hello
Key: abcd
Output: riobkxezg
Reverse the input, olleh, append this with the key i.e. ollehabcd.
EvenString: leac
OddString: olhbd
As key length is 4, 4 times loop will be generated including FibNum 0, which is ignored.
For EvenArray Ciphers:
FibNum: 1
In Even Array for l and FibNum 1 cip is k
In Even Array for e and FibNum 1 cip is d
In Even Array for a and FibNum 1 cip is z
In Even Array for c and FibNum 1 cip is b
FibNum: 2
In Even Array for l and FibNum 2 cip is j
In Even Array for e and FibNum 2 cip is c
In Even Array for a and FibNum 2 cip is y
In Even Array for c and FibNum 2 cip is a
FibNum: 3 (Final Computed letters)
In Even Array for l and FibNum 3 cip is i
In Even Array for e and FibNum 3 cip is b
In Even Array for a and FibNum 3 cip is x
In Even Array for c and FibNum 3 cip is z
For OddArray Ciphers
FibNum: 1
In Odd Array for o and FibNum 1 cip is p
In Odd Array for l and FibNum 1 cip is m
In Odd Array for h and FibNum 1 cip is i
In Odd Array for b and FibNum 1 cip is c
In Odd Array for d and FibNum 1 cip is e
FibNum: 2
In Odd Array for o and FibNum 2 cip is q
In Odd Array for l and FibNum 2 cip is n
In Odd Array for h and FibNum 2 cip is j
In Odd Array for b and FibNum 2 cip is d
In Odd Array for d and FibNum 2 cip is f
FibNum: 3 (Final Computed letters)
In Odd Array for o and FibNum 3 cip is r
In Odd Array for l and FibNum 3 cip is o
In Odd Array for h and FibNum 3 cip is k
In Odd Array for b and FibNum 3 cip is e
In Odd Array for d and FibNum 3 cip is g
Arrange EvenArrayCiphers and OddArrayCiphers in their index order, so final String Cipher will be, riobkxezg
程序：
C++14
#include
using namespace std;
string encryptText(string password, string key)
{
int a = 0, b = 1, c = 0,
m = 0, k = 0, j = 0;
string cipher = "", temp = "";
// Declare a password string
string pw = password;
// Reverse the String
reverse(pw.begin(), pw.end());
pw = pw + key;
// For future Purpose
temp = pw;
string stringArray = temp;
string evenString = "", oddString = "";
// Declare EvenArray for storing
// even index of stringArray
string evenArray;
// Declare OddArray for storing
// odd index of stringArray
string oddArray;
// Storing the positions in their
// respective arrays
for(int i = 0;
i < stringArray.length(); i++)
{
if (i % 2 == 0)
{
oddString = oddString +
stringArray[i];
}
else
{
evenString = evenString +
stringArray[i];
}
}
evenArray = new char[evenString.length()];
oddArray = new char[oddString.length()];
// Generate a Fibonacci Series
// Upto the Key Length
while (m <= key.length())
{
// As it always starts with 1
if (m == 0)
m = 1;
else
{
// Logic For Fibonacci Series
a = b;
b = c;
c = a + b;
for(int i = 0;
i < evenString.length();
i++)
{
// Caesar Cipher Algorithm Start
// for even positions
int p = evenString[i];
int cip = 0;
if (p == '0' || p == '1' ||
p == '2' || p == '3' ||
p == '4' || p == '5' ||
p == '6' || p == '7' ||
p == '8' || p == '9')
{
cip = p - c;
if (cip < '0')
cip = cip + 9;
}
else
{
cip = p - c;
if (cip < 'a')
{
cip = cip + 26;
}
}
evenArray[i] = (char)cip;
// Caesar Cipher Algorithm End
}
for(int i = 0;
i < oddString.length();
i++)
{
// Caesar Cipher Algorithm
// Start for odd positions
int p = oddString[i];
int cip = 0;
if (p == '0' || p == '1' ||
p == '2' || p == '3' ||
p == '4' || p == '5' ||
p == '6' || p == '7' ||
p == '8' || p == '9')
{
cip = p + c;
if (cip > '9')
cip = cip - 9;
}
else
{
cip = p + c;
if (cip > 'z')
{
cip = cip - 26;
}
}
oddArray[i] = (char)cip;
// Caesar Cipher Algorithm End
}
m++;
}
}
// Storing content of even and
// odd array to the string array
for(int i = 0; i < stringArray.size(); i++)
{
if (i % 2 == 0)
{
stringArray[i] = oddArray[k];
k++;
}
else
{
stringArray[i] = evenArray[j];
j++;
}
}
// Generating a Cipher Text
// by stringArray (Caesar Cipher)
for(char d : stringArray)
{
cipher = cipher + d;
}
// Return the Cipher Text
return cipher;
}
// Driver code
int main()
{
string pass = "hello";
string key = "abcd";
cout << encryptText(pass, key);
return 0;
}
// This code is contributed by himanshu77 Java
import java.util.*;
import java.lang.*;
class GFG {
public static void main(String[] args)
{
String pass = "hello";
String key = "abcd";
System.out.println(encryptText(pass, key));
}
public static String encryptText(String password, String key)
{
int a = 0, b = 1, c = 0, m = 0, k = 0, j = 0;
String cipher = "", temp = "";
// Declare a password string
StringBuffer pw = new StringBuffer(password);
// Reverse the String
pw = pw.reverse();
pw = pw.append(key);
// For future Purpose
temp = pw.toString();
char stringArray[] = temp.toCharArray();
String evenString = "", oddString = "";
// Declare EvenArray for storing
// even index of stringArray
char evenArray[];
// Declare OddArray for storing
// odd index of stringArray
char oddArray[];
// Storing the positions in their respective arrays
for (int i = 0; i < stringArray.length; i++) {
if (i % 2 == 0) {
oddString = oddString + Character.toString(stringArray[i]);
}
else {
evenString = evenString + Character.toString(stringArray[i]);
}
}
evenArray = new char[evenString.length()];
oddArray = new char[oddString.length()];
// Generate a Fibonacci Series
// Upto the Key Length
while (m <= key.length()) {
// As it always starts with 1
if (m == 0)
m = 1;
else {
// Logic For Fibonacci Series
a = b;
b = c;
c = a + b;
for (int i = 0; i < evenString.length(); i++) {
// Caesar Cipher Algorithm Start for even positions
int p = evenString.charAt(i);
int cip = 0;
if (p == '0' || p == '1' || p == '2' || p == '3' || p == '4'
|| p == '5' || p == '6'
|| p == '7' || p == '8' || p == '9') {
cip = p - c;
if (cip < '0')
cip = cip + 9;
}
else {
cip = p - c;
if (cip < 'a') {
cip = cip + 26;
}
}
evenArray[i] = (char)cip;
/* Caesar Cipher Algorithm End*/
}
for (int i = 0; i < oddString.length(); i++) {
// Caesar Cipher Algorithm Start for odd positions
int p = oddString.charAt(i);
int cip = 0;
if (p == '0' || p == '1' || p == '2' || p == '3' || p == '4'
|| p == '5' || p == '6'
|| p == '7' || p == '8' || p == '9') {
cip = p + c;
if (cip > '9')
cip = cip - 9;
}
else {
cip = p + c;
if (cip > 'z') {
cip = cip - 26;
}
}
oddArray[i] = (char)cip;
// Caesar Cipher Algorithm End
}
m++;
}
}
// Storing content of even and
// odd array to the string array
for (int i = 0; i < stringArray.length; i++) {
if (i % 2 == 0) {
stringArray[i] = oddArray[k];
k++;
}
else {
stringArray[i] = evenArray[j];
j++;
}
}
// Generating a Cipher Text
// by stringArray (Caesar Cipher)
for (char d : stringArray) {
cipher = cipher + d;
}
// Return the Cipher Text
return cipher;
}
}riobkxezg
结论：
用于密码学的混合算法是有效的，因此，检测模式并解码消息不是很容易。这里，该算法是数学函数和凯撒密码的结合，从而实现了混合密码学算法。