C++实现Atbash密码

详细说明埃特巴什密码是一种替换密码，在该密码中字母表中的字母是反向对应的。例如，A 会被替换为 Z，B 会被替换为 Y，依此类推。


#include <cassert>   /// for assert
#include <iostream>  /// for IO operations
#include <map>       /// for std::map
#include <string>    /// for std::string/** \namespace ciphers* \brief Algorithms for encryption and decryption*/
namespace ciphers {/** \namespace atbash* \brief Functions for the [Atbash* Cipher](https://en.wikipedia.org/wiki/Atbash) implementation*/namespace atbash {std::map<char, char> atbash_cipher_map = {{'a', 'z'}, {'b', 'y'}, {'c', 'x'}, {'d', 'w'}, {'e', 'v'}, {'f', 'u'},{'g', 't'}, {'h', 's'}, {'i', 'r'}, {'j', 'q'}, {'k', 'p'}, {'l', 'o'},{'m', 'n'}, {'n', 'm'}, {'o', 'l'}, {'p', 'k'}, {'q', 'j'}, {'r', 'i'},{'s', 'h'}, {'t', 'g'}, {'u', 'f'}, {'v', 'e'}, {'w', 'd'}, {'x', 'c'},{'y', 'b'}, {'z', 'a'}, {'A', 'Z'}, {'B', 'Y'}, {'C', 'X'}, {'D', 'W'},{'E', 'V'}, {'F', 'U'}, {'G', 'T'}, {'H', 'S'}, {'I', 'R'}, {'J', 'Q'},{'K', 'P'}, {'L', 'O'}, {'M', 'N'}, {'N', 'M'}, {'O', 'L'}, {'P', 'K'},{'Q', 'J'}, {'R', 'I'}, {'S', 'H'}, {'T', 'G'}, {'U', 'F'}, {'V', 'E'},{'W', 'D'}, {'X', 'C'}, {'Y', 'B'}, {'Z', 'A'}, {' ', ' '}};/*** @brief atbash cipher encryption and decryption* @param text Plaintext to be encrypted* @returns encoded or decoded string*/std::string atbash_cipher(const std::string& text) {std::string result;for (char letter : text) {result += atbash_cipher_map[letter];}return result;}}  // namespace atbash
}  // namespace ciphers/*** @brief Self-test implementations* @returns void*/
static void test() {// 1st teststd::string text = "Hello World";std::string expected = "Svool Dliow";std::string encrypted_text = ciphers::atbash::atbash_cipher(text);std::string decrypted_text = ciphers::atbash::atbash_cipher(encrypted_text);assert(expected == encrypted_text);assert(text == decrypted_text);std::cout << "Original text: " << text << std::endl;std::cout << ", Expected text: " << expected << std::endl;std::cout << ", Encrypted text: " << encrypted_text << std::endl;std::cout << ", Decrypted text: " << decrypted_text << std::endl;std::cout << "\nAll tests have successfully passed!\n";
}/*** @brief Main function* @returns 0 on exit*/
int main() {test();  // run self-test implementationsreturn 0;
}

代码详细逐句解释

1. 命名空间定义

namespace ciphers {namespace atbash {

定义了嵌套的命名空间 ciphers::atbash，用于组织和封装Atbash加密算法。

2. 映射表定义

std::map<char, char> atbash_cipher_map = {{'a', 'z'}, {'b', 'y'}, {'c', 'x'}, {'d', 'w'}, {'e', 'v'}, {'f', 'u'},{'g', 't'}, {'h', 's'}, {'i', 'r'}, {'j', 'q'}, {'k', 'p'}, {'l', 'o'},{'m', 'n'}, {'n', 'm'}, {'o', 'l'}, {'p', 'k'}, {'q', 'j'}, {'r', 'i'},{'s', 'h'}, {'t', 'g'}, {'u', 'f'}, {'v', 'e'}, {'w', 'd'}, {'x', 'c'},{'y', 'b'}, {'z', 'a'}, {'A', 'Z'}, {'B', 'Y'}, {'C', 'X'}, {'D', 'W'},{'E', 'V'}, {'F', 'U'}, {'G', 'T'}, {'H', 'S'}, {'I', 'R'}, {'J', 'Q'},{'K', 'P'}, {'L', 'O'}, {'M', 'N'}, {'N', 'M'}, {'O', 'L'}, {'P', 'K'},{'Q', 'J'}, {'R', 'I'}, {'S', 'H'}, {'T', 'G'}, {'U', 'F'}, {'V', 'E'},{'W', 'D'}, {'X', 'C'}, {'Y', 'B'}, {'Z', 'A'}, {' ', ' '}
};

这个映射表定义了每个字母（包括大写和小写）及其对应的Atbash加密字母之间的映射关系。例如：

小写字母 'a' 映射到 'z'。
大写字母 'A' 映射到 'Z'。
空格 ' ' 映射到自身。

3. 加密/解密函数

std::string atbash_cipher(const std::string& text) {std::string result;for (char letter : text) {result += atbash_cipher_map[letter];}return result;
}

参数：
- text：输入的待加密或解密的字符串。
功能：
- 遍历输入字符串的每个字符。
- 使用 atbash_cipher_map 查找每个字符的对应值，并将其追加到结果字符串 result 中。
返回值：
- 返回加密或解密后的结果字符串。

4. 测试函数

static void test() {// 1st teststd::string text = "Hello World";std::string expected = "Svool Dliow";std::string encrypted_text = ciphers::atbash::atbash_cipher(text);std::string decrypted_text = ciphers::atbash::atbash_cipher(encrypted_text);assert(expected == encrypted_text);assert(text == decrypted_text);std::cout << "Original text: " << text << std::endl;std::cout << ", Expected text: " << expected << std::endl;std::cout << ", Encrypted text: " << encrypted_text << std::endl;std::cout << ", Decrypted text: " << decrypted_text << std::endl;std::cout << "\nAll tests have successfully passed!\n";
}

功能：
- 测试 atbash_cipher 函数的正确性。
- 使用示例文本 "Hello World" 进行加密和解密测试。
- 验证加密结果是否与预期一致，并验证解密后的文本是否与原始文本一致。
断言：
- assert(expected == encrypted_text)：确保加密结果正确。
- assert(text == decrypted_text)：确保解密结果与原始文本一致。
输出：
- 打印原始文本、预期文本、加密文本和解密文本。

代码执行流程

测试函数调用：
- 在 main 函数中调用 test 函数。
加密测试：
- 将 "Hello World" 作为输入，调用 atbash_cipher 进行加密。
解密测试：
- 将加密后的字符串再次作为输入，调用 atbash_cipher 进行解密。
验证结果：
- 使用断言验证加密和解密的正确性。
输出结果：
- 打印测试结果。

示例

假设输入文本为 "Hello World"：

加密过程：
- 'H' → 'S'
- 'e' → 'v'
- 'l' → 'o'
- 'l' → 'o'
- 'o' → 'l'
- ' ' → ' '
- 'W' → 'D'
- 'o' → 'l'
- 'r' → 'i'
- 'l' → 'o'
- 'd' → 'w'
加密结果为 "Svool Dliow"。
解密过程：
- 再次调用 atbash_cipher 对加密结果进行解密，应得到原始文本 "Hello World"。