OpenSSL SHA256错误结果

我有下面的代码应该用来计算SHA256文件的。我正在逐块读取文件，并EVP_DigestUpdate用于该块。当我使用包含内容的文件测试代码时

Test Message Hello World

在Windows中，它给我的SHA256值为，97b2bc0cd1c3849436c6532d9c8de85456e1ce926d1e872a1e9b76a33183655f但该值应该为318b20b83a6730b928c46163a2a1cefee4466132731c95c39613acb547ccb715，也可以在此处进行验证。

这是代码：

#include <openssl\evp.h>
#include <iostream>
#include <string>
#include <fstream>
#include <cstdio>
const int MAX_BUFFER_SIZE = 1024;
std::string FileChecksum(std::string, std::string);
int main()
{
    std::string checksum = FileChecksum("C:\\Users\\Dell\\Downloads\\somefile.txt","sha256");
    std::cout << checksum << std::endl;
    return 0;
}

std::string FileChecksum(std::string file_path, std::string algorithm)
{
     EVP_MD_CTX *mdctx;
     const EVP_MD *md;
     unsigned char md_value[EVP_MAX_MD_SIZE];
     int i;
     unsigned int md_len;

     OpenSSL_add_all_digests();
     md = EVP_get_digestbyname(algorithm.c_str());

     if(!md) {
            printf("Unknown message digest %s\n",algorithm);
            exit(1);
     }

     mdctx = EVP_MD_CTX_create();
     std::ifstream readfile(file_path,std::ifstream::in|std::ifstream::binary);
     if(!readfile.is_open())
     {
         std::cout << "COuldnot open file\n";
         return 0;
     }
     readfile.seekg(0, std::ios::end);
     long filelen = readfile.tellg();
     std::cout << "LEN IS " << filelen << std::endl;
     readfile.seekg(0, std::ios::beg);
     if(filelen == -1)
     {
         std::cout << "Return Null \n";
         return 0;
     }

     EVP_DigestInit_ex(mdctx, md, NULL);
     long temp_fil = filelen;
     while(!readfile.eof() && readfile.is_open() && temp_fil>0)
     {

         int bufferS = (temp_fil < MAX_BUFFER_SIZE) ? temp_fil : MAX_BUFFER_SIZE;
         char *buffer = new char[bufferS+1];
         buffer[bufferS] = 0;
         readfile.read(buffer, bufferS);
         std::cout << strlen(buffer) << std::endl;
         EVP_DigestUpdate(mdctx, buffer, strlen(buffer));
         temp_fil -= bufferS;
         delete[] buffer;
     }
     EVP_DigestFinal_ex(mdctx, md_value, &md_len);
     EVP_MD_CTX_destroy(mdctx);

     printf("Digest is: ");
     //char *checksum_msg = new char[md_len];
     //int cx(0);
     for(i = 0; i < md_len; i++)
     {
        //_snprintf(checksum_msg+cx,md_len-cx,"%02x",md_value[i]);
         printf("%02x", md_value[i]);
     }
     //std::string res(checksum_msg);
     //delete[] checksum_msg;

     printf("\n");

     /* Call this once before exit. */
     EVP_cleanup();
     return "";
}

我试图将使用程序生成的哈希值写为string，_snprintf但是没有用。如何生成正确的哈希值并从FileChecksumFunction返回字符串形式的值？平台是Windows。

编辑：似乎问题是由于CRLF问题。由于Windows使用保存文件\r\n，因此计算出的校验和不同。如何处理呢？