P1603 斯诺登的密码

在这里插入图片描述

#include<bits/stdc++.h>
using namespace std;
char dic[30][20]={"zero","one","two","three","four","five","six","seven","eight","nine","ten","eleven","twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty","a","both","another","first","second","third"};//对应
int di[30]={0,1,4,9,16,25,36,49,64,81,00,21,44,69,96,25,56,89,24,61,0,1,4,1,1,4,9};
unsigned long long int a[10],top,flag;
int i,j;
char s[100];
int main()
{
     for(i=1;i<=6;i++)
     {
          scanf("%s",&s);//%s读入遇到空格就停止
          for(j=1;j<=26;j++)
          {
               if(!strcmp(s,dic[j]))//strcmp(s1,s2);如果他们相同,返回0
               {
                    a[++top]=di[j];//用数组存储
                    break;//立即停止寻找
               }
          }
      }
      sort(a+1,a+top+1);//贪心,使越小的数越靠前输出
      for(i=1;i<=top;i++)
      {
           if(flag)//如果不是第一位
           {
                printf("%.2d",a[i]);//限制格式输出
           }
           else
           {
                if(a[i])
                { 
                     printf("%d",a[i]);
                     flag=1;
                }
            }
     }
     if(!flag)printf("0");//特判
     return 0;
}
### 斯诺登密码学 爱德华·斯诺登揭露了许多关于全球监控项目的细节,其中包括大量涉及加密技术和网络安全的内容。虽然斯诺登本身并不是一名程序员或密码学家,但他所揭示的信息强调了强加密的重要性。 对于使用C语言实现的加密解密功能,可以考虑采用常见的对称加密算法如AES (Advanced Encryption Standard),该标准被广泛认为是安全可靠的[^1]。下面是一个简单的基于AES的文件加解密例子: #### AES 文件加密函数 ```c #include <openssl/aes.h> #include <stdio.h> void encrypt_file(const char *input_filename, const char *output_filename, unsigned char key[AES_BLOCK_SIZE]) { FILE *in = fopen(input_filename, "rb"); FILE *out = fopen(output_filename, "wb"); AES_KEY aes_key; AES_set_encrypt_key(key, 128, &aes_key); unsigned char iv[AES_BLOCK_SIZE]; memset(iv, 0x00, sizeof(iv)); int num_rounds = AES_BLOCK_SIZE / sizeof(unsigned long); unsigned char buffer[AES_BLOCK_SIZE], out_buffer[AES_BLOCK_SIZE]; while (!feof(in)) { fread(buffer, 1, AES_BLOCK_SIZE, in); AES_cbc_encrypt(buffer, out_buffer, AES_BLOCK_SIZE, &aes_key, iv, AES_ENCRYPT); fwrite(out_buffer, 1, AES_BLOCK_SIZE, out); } fclose(in); fclose(out); } ``` #### AES 文件解密函数 ```c void decrypt_file(const char *input_filename, const char *output_filename, unsigned char key[AES_BLOCK_SIZE]) { FILE *in = fopen(input_filename, "rb"); FILE *out = fopen(output_filename, "wb"); AES_KEY aes_key; AES_set_decrypt_key(key, 128, &aes_key); unsigned char iv[AES_BLOCK_SIZE]; memset(iv, 0x00, sizeof(iv)); int num_rounds = AES_BLOCK_SIZE / sizeof(unsigned long); unsigned char buffer[AES_BLOCK_SIZE], out_buffer[AES_BLOCK_SIZE]; while (!feof(in)) { fread(buffer, 1, AES_BLOCK_SIZE, in); AES_cbc_encrypt(buffer, out_buffer, AES_BLOCK_SIZE, &aes_key, iv, AES_DECRYPT); fwrite(out_buffer, 1, AES_BLOCK_SIZE, out); } fclose(in); fclose(out); } ``` 上述代码展示了如何通过OpenSSL库来执行基本的AES CBC模式下的文件加密和解密操作。需要注意的是,在实际应用中应当更加注意错误处理、IV初始化向量的安全性和其他潜在的安全隐患。
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