Base64算法C语言实现

最新推荐文章于 2023-11-14 18:47:05 发布

原创最新推荐文章于 2023-11-14 18:47:05 发布 · 514 阅读

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#base64 加密

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本文详细介绍了如何使用Base64算法对指定明文进行加密，并通过头文件和函数声明展示了实现过程。包括参数说明、函数实现以及内存操作等关键步骤。

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使用说明：

XSXSXSblubro.comSXSXSX

1.将红色字体内容复制到主函数前

2.将绿色字体内容复制到主函数之后

参数说明

1.pClerText指向需要加密的明文

2.ClerTextLen明文的长度（单位字节）

3.ppCipherText用于存放密文的地址

4.pCipherTextLen用于存放密文长度的地址

//头文件及函数声明

#include <stdlib.h>
#include <malloc.h>
#include <memory.h>

unsigned int Base64Encrypt(unsigned char *pClerText,unsigned int ClerTextLen,unsigned char **ppCipherText,unsigned int *pCipherTextLen);

//函数实现

unsigned int Base64Encrypt ( unsigned char *pClerText,unsigned int ClerTextLen,unsigned char **ppCipherText,unsigned int *pCipherTextLen )
{
   unsigned char Base64Table[64]={65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,
                                  97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,
                                  48,49,50,51,52,53,54,55,56,57,
                                  43,47};

unsigned int ClerTextBytes,LoopA;

   unsigned char *pClerTextBytes=(unsigned char *)&ClerTextBytes;

   unsigned char *pCipherText;

unsigned int CipherTextLen, EquaSignCount,Remainder;

Remainder=ClerTextLen%3;

   if(Remainder==0)
   {
      CipherTextLen=ClerTextLen/3*4;

EquaSignCount=0;

   }
   else
   {
      CipherTextLen=(ClerTextLen-Remainder)/3*4+4;

if(Remainder==1)

EquaSignCount=2;

else

        EquaSignCount=1;
   }
   pCipherText=(unsigned char *)malloc(CipherTextLen);

if(pCipherText==NULL) return 1;

memset((void *)pCipherText,0,CipherTextLen);

   for(LoopA=0;LoopA<(CipherTextLen/4);LoopA++)
   {
      pClerTextBytes[3]=pClerText[LoopA*3];

if(LoopA*3+1>=ClerTextLen)

pClerTextBytes[2]=0;

else

pClerTextBytes[2]=pClerText[LoopA*3+1];

if(LoopA*3+2>=ClerTextLen)

pClerTextBytes[1]=0;

else

pClerTextBytes[1]=pClerText[LoopA*3+2];

pClerTextBytes[0]=0;

ClerTextBytes=ClerTextBytes>>2;

pCipherText[LoopA*4]=pClerTextBytes[3];

ClerTextBytes=ClerTextBytes>>2;

pCipherText[LoopA*4+1]=pClerTextBytes[2]&63;

ClerTextBytes=ClerTextBytes>>2;

      pCipherText[LoopA*4+2]=pClerTextBytes[1]&63;

      ClerTextBytes=ClerTextBytes>>2;

pCipherText[LoopA*4+3]=pClerTextBytes[0]&63;

   }
   for(LoopA=0;LoopA<CipherTextLen;LoopA++)
   {
      pCipherText[LoopA]=Base64Table[pCipherText[LoopA]];
   }
   if(EquaSignCount==1)
   {
      pCipherText[CipherTextLen-1]=61;
   }
   if(EquaSignCount==2)
   {
      pCipherText[CipherTextLen-2]=61;