OpenSSL安装：
1.github下载最新的OpenSSL：https://github.com/openssl/openssl
2.在linux解压压缩包
3.安装OpenSSL
./config --prefix=/usr/local --openssldir=/usr/local/ssl
make && make install
./config shared --prefix=/usr/local --openssldir=/usr/local/ssl
make clean
make && make install
4.用ln将需要的so文件链接到/usr/lib或者/lib这两个默认的目录下面
ln -s /where/you/install/lib/*.so /usr/lib
sudo ldconfig
openssl MD5接口：
int MD5_Init(MD5_CTX *c);
//初始化MD5上下文结构 int MD5_Update(MD5_CTX *c, const void *data, size_t len);
//刷新MD5，将文件连续数据分片放入进行MD5刷新。 int MD5_Final(unsigned char *md, MD5_CTX *c);
//产生最终的MD5数据 unsigned char *MD5(const unsigned char *d, size_t n, unsigned char *md);
//直接产生字符串的MD5
代码实现：
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <openssl/md5.h> using namespace std; #define MAXDATABUFF 1024
#define MD5LENTH 16 int main(int arc,char *arv[])
{
string strFilePath = arv[];
ifstream ifile(strFilePath.c_str(),ios::in|ios::binary); //打开文件
unsigned char MD5result[MD5LENTH];
do
{
if (ifile.fail()) //打开失败不做文件MD5
{
cout<<"open file failure!so only display string MD5!"<<endl;
break;
}
MD5_CTX md5_ctx;
MD5_Init(&md5_ctx); char DataBuff[MAXDATABUFF];
while(!ifile.eof())
{
ifile.read(DataBuff,MAXDATABUFF); //读文件
int length = ifile.gcount();
if(length)
{
MD5_Update(&md5_ctx,DataBuff,length); //将当前文件块加入并更新MD5
}
}
MD5_Final(MD5result,&md5_ctx); //获取MD5
cout<<"file MD5:"<<endl;
for(int i = ; i < MD5LENTH; i++) //将MD5以16进制输出
cout<< hex <<(int)MD5result[i];
cout<<endl;
}while(false); MD5((const unsigned char*)strFilePath.c_str(),strFilePath.size(),MD5result); //获取字符串MD5
cout<<"string MD5:"<<endl;
for(int i = ; i < MD5LENTH; i++)
cout << hex << (int)MD5result[i];
cout<<endl;
return ;
}
SConstruct：
Program('md5','md5.cpp',LIBS = ['ssl','crypto'])
测试结果与命令行比较：