利用OPENSSL 实现MD5加密。

#include <stdio.h>
#include "openssl/evp.h"
#include "openssl/md5.h"

#include<iostream>
using namespace std;

void main()
{
    bool do_encrypt(unsigned char *inBuffer,int inLen,unsigned char *outBuffer,int * pOutLen);
    void print_hex(unsigned char *buf,unsigned int len);

unsigned char inBuffer[];
unsigned char OutBuffer[];

char c=' ';
int i=,outLen=;

cout<<"请输入需要加密的明文，以*作为结束符：";
while(c!='*')
{
c=getchar();
inBuffer[i++]=c;
}
cout<<endl;
do_encrypt(inBuffer,i-,OutBuffer,&outLen);

cout<<"使用MD进行加密,生成的密文为:";
print_hex(OutBuffer,outLen);
cout<<endl<<endl; 

system("pause");
}

   bool do_encrypt(unsigned char *inBuffer,int inLen,unsigned char *outBuffer,int *pOutLen)
{
    unsigned int tmplen;
    EVP_MD_CTX ctx; 

    EVP_MD_CTX_init(&ctx);//step1

    EVP_DigestInit(&ctx,EVP_md5());//step2

    if(!EVP_DigestUpdate(&ctx,inBuffer,inLen))//step3
    {
        return false;
    }

    if(!EVP_DigestFinal(&ctx,outBuffer+*pOutLen,&tmplen))//step4
    {
        return false;
    }
*pOutLen+=tmplen;
EVP_MD_CTX_cleanup(&ctx);
    return true;
}

 void print_hex(unsigned char *buf,unsigned int len)
{
    for(int i=;i<len;i++)
        printf("%0.2x",buf[i]);
}

环境的配置在前面的文章已经讲过。