Delphi 使用Windows API(WinCrypt)计算文件MD5哈希，支持大文件-木庄网络博客

本文整理自网络，侵删。
 Delphi 默认没有WinCrypt相关函数的定义所以引用JwaWinCrypt{jedi-apilib}单元

将 CryptCreateHash(hProv, CALG_MD5,0, 0, hHash)中的参数CALG_MD5

修改为CALG_SHA1即为计算SHA1哈希 值得注意的时CALG_SHA_256，CALG_SHA_384，CALG_SHA_512

着三个算法是在Windows XP SP3才开始支持的  XP SP2~ Win2000是不支持的！！



program Project2;
 
{$APPTYPE CONSOLE}
 
uses
  Winapi.Windows,
  System.SysUtils,
  System.Classes,
  System.Math,
  JwaWinCrypt;
 
 
Function GetFileSizeEx(hFile: THandle; Var lpFileSizeHigh :UInt64):Boolean; stdcall; external kernel32 name 'GetFileSizeEx';
 
 
Function GetFileHash4Md5(FileDirectory :PChar):String;
Const
  Buffer_Threshold = 1024 * 1024;
Label OnFail;
Var
  hFile      :THandle;
  hMapFile   :THandle;
  dwFileSize :UInt64;
  dwFileSizeH:DWORD;
 
  hProv      :HCRYPTPROV;
  hHash      :HCRYPTHASH;
  iIndex     :UInt64;
  dwBufSize  :DWORD;
  lpBuffer   :PByte;
 
  lpHash     :Array [0..MAXCHAR] Of Byte;
  dwHashLen  :DWORD;
  szHash     :Array [0..MAXCHAR] Of Char;
begin
  Writeln('文件：', FileDirectory);
  Result   := '';
  lpBuffer := Nil;
  hMapFile := INVALID_HANDLE_VALUE;
  hFile    := CreateFile(FileDirectory, GENERIC_READ, FILE_SHARE_READ, Nil,OPEN_EXISTING, 0, 0);
  if hFile = INVALID_HANDLE_VALUE then
  begin
    Writeln('CreateFile Error, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
 
  if Not GetFileSizeEx(hFile, dwFileSize) then
  begin
    Writeln('GetFileSizeEx Error, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
  Writeln('大小：', dwFileSize, ' 字节');
 
  hMapFile := CreateFileMapping(hFile, Nil, PAGE_READONLY, 0, 0, Nil);
  if hMapFile = INVALID_HANDLE_VALUE then
  begin
    Writeln('CreateFileMapping Error, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
 
  if Not CryptAcquireContext(hProv, Nil, Nil, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT Or CRYPT_MACHINE_KEYSET) Then
  begin
    Writeln('CryptAcquireContext Error, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
 
  if Not CryptCreateHash(hProv, CALG_MD5,0, 0, hHash) Then
  begin
    Writeln('CryptCreateHash Error, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
 
  iIndex := 0;
  while iIndex < dwFileSize do
  begin
    dwBufSize := Min(dwFileSize - iIndex, Buffer_Threshold);
    lpBuffer  := MapViewOfFile(hMapFile, FILE_MAP_READ, Int64Rec(iIndex).Hi, Int64Rec(iIndex).Lo, dwBufSize);
    if lpBuffer = Nil then
    begin
      Writeln('MapViewOfFile Error, ErrorCode:', GetLastError);
      Goto OnFail;
    end;
 
    if Not CryptHashData(hHash, lpBuffer, dwBufSize, 0) then
    begin
      Writeln('CryptHashData Error, ErrorCode:', GetLastError);
      Goto OnFail;
    end;
 
    UnmapViewOfFile(lpBuffer);
    Inc(iIndex, Buffer_Threshold);
  end;
 
  dwBufSize := SizeOf(DWORD);
  dwHashLen := 0;
  if CryptGetHashParam(hHash, HP_HASHSIZE, @dwHashLen, dwBufSize, 0) then
  begin
    ZeroMemory(@lpHash, SizeOf(lpHash));
    if CryptGetHashParam(hHash, HP_HASHVAL, @lpHash, dwHashLen, 0) Then
    begin
      for dwFileSizeH := 0 to dwHashLen-1 do
      begin
        wsprintf(@szHash, '%s%02x', szHash, lpHash[dwFileSizeH]);
      end;
      Writeln('MD5：', String(szHash));
    end Else
    begin
      Writeln('Error getting hash value, ErrorCode:', GetLastError);
      Goto OnFail;
    end;  
  end Else
  begin
    Writeln('Error getting hash length value, ErrorCode:', GetLastError);
    Goto OnFail;
  end;
 
OnFail:
  CryptDestroyHash(hHash);
  CryptReleaseContext(hProv, 0);
  UnmapViewOfFile(lpBuffer);
  CloseHandle(hFile);
  CloseHandle(hMapFile);
end;
 
 
begin
  GetFileHash4Md5('E:\ISO\cn_windows_server_2016_updated_feb_2018_x64_dvd_11636703.iso');
  Readln;
end.

来源：https://www.7xcode.com/archives/139.html
Delphi 使用Windows API(WinCrypt)计算文件MD5哈希，支持大文件

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