VC++使用DES算法进行文件加密和解密

头文件：

extern "C"
{
BOOL xEncrypt(LPCTSTR lpszSource, LPCTSTR lpszDestination, LPCTSTR lpszPassword);
BOOL xDecrypt(LPCTSTR lpszSource, LPCTSTR lpszDestination, LPCTSTR lpszPassword);
}

cpp文件：
#include "stdafx.h"
#include "xEncrypt.h"

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <wincrypt.h>

#define BLOCK_SIZE 1000
#define BUFFER_SIZE 1008

// 加密文件
BOOL xEncrypt(LPCTSTR lpszSource, LPCTSTR lpszDestination, LPCTSTR lpszPassword)
{
FILE *hSrcFile = NULL, *hDestFile = NULL;

HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
HCRYPTKEY hKey = 0, hXchgKey = 0;
PBYTE pbBuffer = NULL, pbKeyBlob = NULL;
BOOL bEOF = FALSE, bReturn = FALSE;
DWORD dwCount = 0, dwKeyBlobLen = 0;

if (_wfopen_s(&hSrcFile, lpszSource, TEXT("rb")) != 0)
{
goto exit;
}

if (_wfopen_s(&hDestFile, lpszDestination, TEXT("wb")) != 0)
{
goto exit;
}

if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0))
{
DWORD ret = GetLastError();
if (ret != NTE_BAD_KEYSET)
{
goto exit;
}
else
{
if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET))
{
goto exit;
}
}
}

if (lpszPassword == NULL)
{
if (!CryptGenKey(hProv, CALG_RC2, CRYPT_EXPORTABLE, &hKey))
{
goto exit;
}

if (!CryptGetUserKey(hProv, AT_KEYEXCHANGE, &hXchgKey))
{
DWORD ret = GetLastError();
if (ret != NTE_NO_KEY)
{
goto exit;
}
if (!CryptGenKey(hProv,AT_KEYEXCHANGE,NULL,&hXchgKey))
{
goto exit;
}
}

if (!CryptExportKey(hKey, hXchgKey, SIMPLEBLOB, 0, NULL, &dwKeyBlobLen))
{
goto exit;
}

if ((pbKeyBlob = (PBYTE)malloc(dwKeyBlobLen)) == NULL)
{
goto exit;
}

if (!CryptExportKey (hKey, hXchgKey, SIMPLEBLOB, 0, pbKeyBlob, &dwKeyBlobLen))
{
goto exit;
}

fwrite (&dwKeyBlobLen, sizeof (DWORD), 1, hDestFile);

if (ferror (hDestFile))
{
goto exit;
}

fwrite (pbKeyBlob, 1, dwKeyBlobLen, hDestFile);

if (ferror(hDestFile))
{
goto exit;
}
}
else
{
if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
{
goto exit;
}

if (!CryptHashData(hHash, (PBYTE)lpszPassword, wcslen (lpszPassword), 0))
{
goto exit;
}

if (!CryptDeriveKey(hProv, CALG_RC2, hHash, 0, &hKey))
{
goto exit;
}
}

if ((pbBuffer=(PBYTE)malloc(BUFFER_SIZE)) == NULL)
{
goto exit;
}

do
{
dwCount = fread(pbBuffer, 1, BLOCK_SIZE, hSrcFile);

if (ferror(hSrcFile))
{
goto exit;
}
bEOF = feof(hSrcFile);

if (!CryptEncrypt(hKey, 0, bEOF, 0, pbBuffer, &dwCount, BUFFER_SIZE))
{
goto exit;
}

fwrite(pbBuffer, 1, dwCount, hDestFile);
if (ferror(hDestFile))
{
goto exit;
}

} while (!bEOF);

bReturn = TRUE;

exit:
if (hSrcFile) fclose(hSrcFile);
if (hDestFile) fclose(hDestFile);
if (pbKeyBlob) free(pbKeyBlob);
if (pbBuffer) free(pbBuffer);
if (hKey) CryptDestroyKey(hKey);
if (hXchgKey) CryptDestroyKey(hXchgKey);
if (hHash) CryptDestroyHash(hHash);
if (hProv) CryptReleaseContext(hProv, 0);

return bReturn;
}

// 解密文件
BOOL xDecrypt (LPCTSTR lpszSource, LPCTSTR lpszDestination, LPCTSTR lpszPassword)
{
FILE *hSrcFile = NULL, *hDestFile = NULL;

HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
HCRYPTKEY hKey = 0;

PBYTE pbBuffer = NULL, pbKeyBlob = NULL;
BOOL bEOF = 0, bReturn = FALSE;
DWORD dwCount = 0, dwKeyBlobLen = 0;

if (_wfopen_s(&hSrcFile, lpszSource, TEXT("rb")) != 0)
{
goto exit;
}

if (_wfopen_s(&hDestFile, lpszDestination, TEXT("wb")) != 0)
{
goto exit;
}

if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0))
{
DWORD ret = GetLastError();
if (ret != NTE_BAD_KEYSET)
{
goto exit;
}
else
{
if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET))
{
goto exit;
}
}
}

if (lpszPassword == NULL)
{
fread(&dwKeyBlobLen, sizeof (DWORD), 1, hSrcFile);
if (ferror(hSrcFile) || feof (hSrcFile))
{
goto exit;
}

if ((pbKeyBlob = (PBYTE)malloc(dwKeyBlobLen)) == NULL)
{
goto exit;
}

fread(pbKeyBlob, 1, dwKeyBlobLen, hSrcFile);

if (ferror(hSrcFile) || feof(hSrcFile))
{
goto exit;
}

if (!CryptImportKey(hProv, pbKeyBlob, dwKeyBlobLen, 0, 0, &hKey))
{
goto exit;
}
}
else
{
if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
{
goto exit;
}

if (!CryptHashData(hHash, (PBYTE)lpszPassword, wcslen(lpszPassword), 0))
{
goto exit;
}

if (!CryptDeriveKey(hProv, CALG_RC2, hHash, 0, &hKey))
{
goto exit;
}
}

if ((pbBuffer = (PBYTE)malloc(BUFFER_SIZE)) == NULL)
{
goto exit;
}

do
{
dwCount = fread(pbBuffer, 1, BLOCK_SIZE, hSrcFile);

if (ferror(hSrcFile))
{
goto exit;
}

bEOF = feof(hSrcFile);

if (!CryptDecrypt(hKey, 0, bEOF, 0, pbBuffer, &dwCount))
{
goto exit;
}

fwrite(pbBuffer, 1, dwCount, hDestFile);
if (ferror(hDestFile))
{
goto exit;
}

} while (!bEOF);

bReturn = TRUE;
exit:
if (hSrcFile) fclose(hSrcFile);
if (hDestFile) fclose(hDestFile);
if (pbKeyBlob) free(pbKeyBlob);
if (pbBuffer) free(pbBuffer);
if (hKey) CryptDestroyKey(hKey);
if (hHash) CryptDestroyHash(hHash);
if (hProv) CryptReleaseContext (hProv, 0);

return bReturn;

}