md5sum
计算并显示文件MD5的方法。它需要与OpenSSL库链接(gcc md5.c -o md5 -lssl
)才能正常工作。它是纯C语言编写的,但你应该能够很容易地将其适配到你的C++应用程序中。#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/md5.h>
unsigned char result[MD5_DIGEST_LENGTH];
// Print the MD5 sum as hex-digits.
void print_md5_sum(unsigned char* md) {
int i;
for(i=0; i <MD5_DIGEST_LENGTH; i++) {
printf("%02x",md[i]);
}
}
// Get the size of the file by its file descriptor
unsigned long get_size_by_fd(int fd) {
struct stat statbuf;
if(fstat(fd, &statbuf) < 0) exit(-1);
return statbuf.st_size;
}
int main(int argc, char *argv[]) {
int file_descript;
unsigned long file_size;
char* file_buffer;
if(argc != 2) {
printf("Must specify the file\n");
exit(-1);
}
printf("using file:\t%s\n", argv[1]);
file_descript = open(argv[1], O_RDONLY);
if(file_descript < 0) exit(-1);
file_size = get_size_by_fd(file_descript);
printf("file size:\t%lu\n", file_size);
file_buffer = mmap(0, file_size, PROT_READ, MAP_SHARED, file_descript, 0);
MD5((unsigned char*) file_buffer, file_size, result);
munmap(file_buffer, file_size);
print_md5_sum(result);
printf(" %s\n", argv[1]);
return 0;
}
gcc md5.c -o md5 -lcrypto
这个命令行比 -lssl
命令行更有效。 - RajaRaviVarma#include <openssl/md5.h>
QByteArray AESWrapper::md5 ( const QByteArray& data) {
unsigned char * tmp_hash;
tmp_hash = MD5((const unsigned char*)data.constData(), data.length(), NULL);
return QByteArray((const char*)tmp_hash, MD5_DIGEST_LENGTH);
}
return QCryptographicHash::hash(data, QCryptographicHash::Md5);
作为函数的主体... - akira如果您从"https://stackoverflow.com/questions/4393017/md5-implementation-in-c"重定向到此处,是因为它错误地被标记为重复。
这里的示例可以正常工作:
http://www.zedwood.com/article/cpp-md5-function
如果您正在使用VC++2010编译,则需要将其main.cpp更改为以下内容:
#include <iostream> //for std::cout
#include <string.h> //for std::string
#include "MD5.h"
using std::cout; using std::endl;
int main(int argc, char *argv[])
{
std::string Temp = md5("The quick brown fox jumps over the lazy dog");
cout << Temp.c_str() << endl;
return 0;
}
如果您想要读取char *数组而不是字符串来回答这个页面上的问题,那么您需要稍微修改MD5类。
编辑:
显然修改MD5库并不清楚,因此在此为您提供完整的VC++2010解决方案,以便包括char *:
https://github.com/alm4096/MD5-Hash-Example-VS
这里有一些解释:
#include <iostream> //for std::cout
#include <string.h> //for std::string
#include <fstream>
#include "MD5.h"
using std::cout; using std::endl;
int main(int argc, char *argv[])
{
//Start opening your file
ifstream inBigArrayfile;
inBigArrayfile.open ("Data.dat", std::ios::binary | std::ios::in);
//Find length of file
inBigArrayfile.seekg (0, std::ios::end);
long Length = inBigArrayfile.tellg();
inBigArrayfile.seekg (0, std::ios::beg);
//read in the data from your file
char * InFileData = new char[Length];
inBigArrayfile.read(InFileData,Length);
//Calculate MD5 hash
std::string Temp = md5(InFileData,Length);
cout << Temp.c_str() << endl;
//Clean up
delete [] InFileData;
return 0;
}
我只是在MD5库中加入了以下内容:
MD5.cpp:
MD5::MD5(char * Input, long length)
{
init();
update(Input, length);
finalize();
}
MD5.h:
std::string md5(char * Input, long length);
我刚刚需要一个跨平台解决方案,适用于c++11、boost和openssl。我以D'Nabre的方案为起点,将其精简为以下内容:
#include <openssl/md5.h>
#include <iomanip>
#include <sstream>
#include <boost/iostreams/device/mapped_file.hpp>
const std::string md5_from_file(const std::string& path)
{
unsigned char result[MD5_DIGEST_LENGTH];
boost::iostreams::mapped_file_source src(path);
MD5((unsigned char*)src.data(), src.size(), result);
std::ostringstream sout;
sout<<std::hex<<std::setfill('0');
for(auto c: result) sout<<std::setw(2)<<(int)c;
return sout.str();
}
一个快速测试可执行文件的示例:
#include <iostream>
int main(int argc, char *argv[]) {
if(argc != 2) {
std::cerr<<"Must specify the file\n";
exit(-1);
}
std::cout<<md5_from_file(argv[1])<<" "<<argv[1]<<std::endl;
return 0;
}
一些链接的注意事项:
Linux: -lcrypto -lboost_iostreams
Windows: -DBOOST_ALL_DYN_LINK libeay32.lib ssleay32.lib
QFile file("bigimage.jpg");
if (file.open(QIODevice::ReadOnly))
{
QByteArray fileData = file.readAll();
QByteArray hashData = QCryptographicHash::hash(fileData,QCryptographicHash::Md5); // or QCryptographicHash::Sha1
qDebug() << hashData.toHex(); // 0e0c2180dfd784dd84423b00af86e2fc
}
md5.h
还有MD5_*
函数,非常适用于大文件。
#include <openssl/md5.h>
#include <fstream>
.......
std::ifstream file(filename, std::ifstream::binary);
MD5_CTX md5Context;
MD5_Init(&md5Context);
char buf[1024 * 16];
while (file.good()) {
file.read(buf, sizeof(buf));
MD5_Update(&md5Context, buf, file.gcount());
}
unsigned char result[MD5_DIGEST_LENGTH];
MD5_Final(result, &md5Context);
#include <sstream>
#include <iomanip>
.......
std::stringstream md5string;
md5string << std::hex << std::uppercase << std::setfill('0');
for (const auto &byte: result)
md5string << std::setw(2) << (int)byte;
return md5string.str();
@D'Nabre对C++的实现进行了重新制作。不要忘记在最后使用-lcrypto编译:gcc md5.c -o md5 -lcrypto
。
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <openssl/md5.h>
using namespace std;
unsigned char result[MD5_DIGEST_LENGTH];
// function to print MD5 correctly
void printMD5(unsigned char* md, long size = MD5_DIGEST_LENGTH) {
for (int i=0; i<size; i++) {
cout<< hex << setw(2) << setfill('0') << (int) md[i];
}
}
int main(int argc, char *argv[]) {
if(argc != 2) {
cout << "Specify the file..." << endl;
return 0;
}
ifstream::pos_type fileSize;
char * memBlock;
ifstream file (argv[1], ios::ate);
//check if opened
if (file.is_open() ) { cout<< "Using file\t"<< argv[1]<<endl; }
else {
cout<< "Unnable to open\t"<< argv[1]<<endl;
return 0;
}
//get file size & copy file to memory
//~ file.seekg(-1,ios::end); // exludes EOF
fileSize = file.tellg();
cout << "File size \t"<< fileSize << endl;
memBlock = new char[fileSize];
file.seekg(0,ios::beg);
file.read(memBlock, fileSize);
file.close();
//get md5 sum
MD5((unsigned char*) memBlock, fileSize, result);
//~ cout << "MD5_DIGEST_LENGTH = "<< MD5_DIGEST_LENGTH << endl;
printMD5(result);
cout<<endl;
return 0;
}
#include <sha.h>
#include <iostream>
SHA256 sha;
while ( !f.eof() ) {
char buff[4096];
int numchars = f.read(...);
sha.Update(buff, numchars);
}
char hash[size];
sha.Final(hash);
cout << hash <<endl;
我需要的是类似的东西,因为我不能读取多GB的文件来计算哈希值。理论上我可以对它们进行内存映射,但我必须支持32位平台——对于大文件仍然存在问题。
md5sum
或类似工具进行比较。 - warren