unit U_md5;

{
1、 MD5String、MD5File、MD5Print、MD5Match这四个函数是供调用的。其他是用来辅助这几个函数的子函数。
2、MD5String为加密字符串。
3、MD5File为加密这个文件。
4、MD5Print是将加密后的密文转换成字符串。
5、MD5Match是用来比较密文是否一致。

加密字符串aaa MD5String('aaa')
将加密后的aaa显示出来 MD5Print(MD5String('aaa'))
比较两次密文是否一致： MD5Match(MD5String('第一次明文'),MD5String('第二次输入的明文'))

  }
 
interface

uses
  Windows,SysUtils;
 
type 
  MD5Count = array[0..1] of DWORD;
  MD5State = array[0..3] of DWORD;
  MD5Block = array[0..15] of DWORD;
  MD5CBits = array[0..7] of byte;
  MD5Digest = array[0..15] of byte;
  MD5Buffer = array[0..63] of byte;
  MD5Context = record
  State: MD5State;
  Count: MD5Count;
  Buffer: MD5Buffer;
  end;
 
  procedure MD5Init(var Context: MD5Context);
  procedure MD5Update(var Context: MD5Context; Input: pChar; Length: longword);
  procedure MD5Final(var Context: MD5Context; var Digest: MD5Digest);
 
  function MD5String(M: string): MD5Digest;
  function MD5File(N: string): MD5Digest;
  function MD5Print(D: MD5Digest): string;
 
  function MD5Match(D1, D2: MD5Digest): boolean;
 
 
implementation
 
var
  PADDING: MD5Buffer = (
  $80, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00,
  $00, $00, $00, $00, $00, $00, $00, $00
  );
 
function F(x, y, z: DWORD): DWORD; 
begin 
  Result := (x and y) or ((not x) and z);
end; 
 
function G(x, y, z: DWORD): DWORD; 
begin 
  Result := (x and z) or (y and (not z));
end; 
 
function H(x, y, z: DWORD): DWORD; 
begin 
  Result := x xor y xor z;
end; 
 
function I(x, y, z: DWORD): DWORD; 
begin 
  Result := y xor (x or (not z));
end; 
 
procedure rot(var x: DWORD; n: BYTE); 
begin 
  x := (x shl n) or (x shr (32 - n));
end; 
 
procedure FF(var a: DWORD; b, c, d, x: DWORD; s: BYTE; ac: DWORD); 
begin 
  inc(a, F(b, c, d) + x + ac);
  rot(a, s);
  inc(a, b);
end; 
 
procedure GG(var a: DWORD; b, c, d, x: DWORD; s: BYTE; ac: DWORD); 
begin 
  inc(a, G(b, c, d) + x + ac);
  rot(a, s);
  inc(a, b);
end; 
 
procedure HH(var a: DWORD; b, c, d, x: DWORD; s: BYTE; ac: DWORD); 
begin 
  inc(a, H(b, c, d) + x + ac);
  rot(a, s);
  inc(a, b);
end; 
 
procedure II(var a: DWORD; b, c, d, x: DWORD; s: BYTE; ac: DWORD); 
begin 
  inc(a, I(b, c, d) + x + ac);
  rot(a, s);
  inc(a, b);
end; 
 
// ----------------------------------------------------------------------------------------------- 

//  加密指定长度（字节）
procedure Encode(Source, Target: pointer; Count: longword);
var 
  S: PByte;
  T: PDWORD;
  I: longword;
begin 
  S := Source;
  T := Target;
  for I := 1 to Count div 4 do begin
    T^ := S^;
    inc(S);
    T^ := T^ or (S^ shl 8);
    inc(S);
    T^ := T^ or (S^ shl 16);
    inc(S);
    T^ := T^ or (S^ shl 24);
    inc(S);
    inc(T);
  end;
end;

// 解密指定字节长度
procedure Decode(Source, Target: pointer; Count: longword);
var
  S: PDWORD;
  T: PByte;
  I: longword;
begin 
  S := Source;
  T := Target;
  for I := 1 to Count do
  begin
    T^ := S^ and $ff;
    inc(T);
    T^ := (S^ shr 8) and $ff;
    inc(T);
    T^ := (S^ shr 16) and $ff;
    inc(T);
    T^ := (S^ shr 24) and $ff;
    inc(T);
    inc(S);
  end;
end;
 
// Transform State according to first 64 bytes at Buffer 
procedure Transform(Buffer: pointer; var State: MD5State); 
var 
  a, b, c, d: DWORD;
  Block: MD5Block;
begin
  Encode(Buffer, @Block, 64);
  a := State[0];
  b := State[1];
  c := State[2];
  d := State[3];
  FF (a, b, c, d, Block[ 0], 7, $d76aa478);
  FF (d, a, b, c, Block[ 1], 12, $e8c7b756); 
  FF (c, d, a, b, Block[ 2], 17, $242070db);
  FF (b, c, d, a, Block[ 3], 22, $c1bdceee);
  FF (a, b, c, d, Block[ 4], 7, $f57c0faf); 
  FF (d, a, b, c, Block[ 5], 12, $4787c62a);
  FF (c, d, a, b, Block[ 6], 17, $a8304613); 
  FF (b, c, d, a, Block[ 7], 22, $fd469501);
  FF (a, b, c, d, Block[ 8], 7, $698098d8);
  FF (d, a, b, c, Block[ 9], 12, $8b44f7af); 
  FF (c, d, a, b, Block[10], 17, $ffff5bb1);
  FF (b, c, d, a, Block[11], 22, $895cd7be);
  FF (a, b, c, d, Block[12], 7, $6b901122); 
  FF (d, a, b, c, Block[13], 12, $fd987193);
  FF (c, d, a, b, Block[14], 17, $a679438e);
  FF (b, c, d, a, Block[15], 22, $49b40821); 
  GG (a, b, c, d, Block[ 1], 5, $f61e2562); 
  GG (d, a, b, c, Block[ 6], 9, $c040b340); 
  GG (c, d, a, b, Block[11], 14, $265e5a51); 
  GG (b, c, d, a, Block[ 0], 20, $e9b6c7aa); 
  GG (a, b, c, d, Block[ 5], 5, $d62f105d); 
  GG (d, a, b, c, Block[10], 9, $2441453);
  GG (c, d, a, b, Block[15], 14, $d8a1e681);
  GG (b, c, d, a, Block[ 4], 20, $e7d3fbc8);
  GG (a, b, c, d, Block[ 9], 5, $21e1cde6);
  GG (d, a, b, c, Block[14], 9, $c33707d6);
  GG (c, d, a, b, Block[ 3], 14, $f4d50d87); 
  GG (b, c, d, a, Block[ 8], 20, $455a14ed); 
  GG (a, b, c, d, Block[13], 5, $a9e3e905);
  GG (d, a, b, c, Block[ 2], 9, $fcefa3f8);
  GG (c, d, a, b, Block[ 7], 14, $676f02d9);
  GG (b, c, d, a, Block[12], 20, $8d2a4c8a);
  HH (a, b, c, d, Block[ 5], 4, $fffa3942);
  HH (d, a, b, c, Block[ 8], 11, $8771f681);
  HH (c, d, a, b, Block[11], 16, $6d9d6122);
  HH (b, c, d, a, Block[14], 23, $fde5380c);
  HH (a, b, c, d, Block[ 1], 4, $a4beea44);
  HH (d, a, b, c, Block[ 4], 11, $4bdecfa9);
  HH (c, d, a, b, Block[ 7], 16, $f6bb4b60);
  HH (b, c, d, a, Block[10], 23, $bebfbc70);
  HH (a, b, c, d, Block[13], 4, $289b7ec6);
  HH (d, a, b, c, Block[ 0], 11, $eaa127fa); 
  HH (c, d, a, b, Block[ 3], 16, $d4ef3085); 
  HH (b, c, d, a, Block[ 6], 23, $4881d05);
  HH (a, b, c, d, Block[ 9], 4, $d9d4d039);
  HH (d, a, b, c, Block[12], 11, $e6db99e5);
  HH (c, d, a, b, Block[15], 16, $1fa27cf8);
  HH (b, c, d, a, Block[ 2], 23, $c4ac5665); 
  II (a, b, c, d, Block[ 0], 6, $f4292244); 
  II (d, a, b, c, Block[ 7], 10, $432aff97);
  II (c, d, a, b, Block[14], 15, $ab9423a7);
  II (b, c, d, a, Block[ 5], 21, $fc93a039);
  II (a, b, c, d, Block[12], 6, $655b59c3);
  II (d, a, b, c, Block[ 3], 10, $8f0ccc92);
  II (c, d, a, b, Block[10], 15, $ffeff47d); 
  II (b, c, d, a, Block[ 1], 21, $85845dd1); 
  II (a, b, c, d, Block[ 8], 6, $6fa87e4f);
  II (d, a, b, c, Block[15], 10, $fe2ce6e0); 
  II (c, d, a, b, Block[ 6], 15, $a3014314); 
  II (b, c, d, a, Block[13], 21, $4e0811a1);
  II (a, b, c, d, Block[ 4], 6, $f7537e82); 
  II (d, a, b, c, Block[11], 10, $bd3af235); 
  II (c, d, a, b, Block[ 2], 15, $2ad7d2bb);
  II (b, c, d, a, Block[ 9], 21, $eb86d391);
  inc(State[0], a);
  inc(State[1], b);
  inc(State[2], c);
  inc(State[3], d);
end;
// -----------------------------------------------------------------------------------------------
 
// 初始化给定内容
procedure MD5Init(var Context: MD5Context); 
begin 
  with Context do
  begin
    State[0] := $67452301;
    State[1] := $efcdab89;
    State[2] := $98badcfe;
    State[3] := $10325476;
    Count[0] := 0;
    Count[1] := 0;
    ZeroMemory(@Buffer, SizeOf(MD5Buffer));
  end;
end; 
 
// 更新给定内容  Update given Context to include Length bytes of Input
procedure MD5Update(var Context: MD5Context; Input: pChar; Length: longword); 
var 
  Index: longword;
  PartLen: longword;
  I: longword;
begin 
  with Context do
  begin
    Index := (Count[0] shr 3) and $3f;
    inc(Count[0], Length shl 3);
    if Count[0] < (Length shl 3) then inc(Count[1]);
    inc(Count[1], Length shr 29);
  end;
  PartLen := 64 - Index;
  if Length >= PartLen then
  begin
    CopyMemory(@Context.Buffer[Index], Input, PartLen);
    Transform(@Context.Buffer, Context.State);
    I := PartLen;
    while I + 63 < Length do
    begin
      Transform(@Input[I], Context.State);
      inc(I, 64);
    end;
    Index := 0;
  end
  else I := 0;
  CopyMemory(@Context.Buffer[Index], @Input[I], Length - I);
end;
 
// Finalize given Context, create Digest and zeroize Context
procedure MD5Final(var Context: MD5Context; var Digest: MD5Digest);
var
  Bits: MD5CBits;
  Index: longword;
  PadLen: longword;
begin 
  Decode(@Context.Count, @Bits, 2);
  Index := (Context.Count[0] shr 3) and $3f;
  if Index < 56 then PadLen := 56 - Index else PadLen := 120 - Index;
  MD5Update(Context, @PADDING, PadLen);
  MD5Update(Context, @Bits, 8);
  Decode(@Context.State, @Digest, 4);
  ZeroMemory(@Context, SizeOf(MD5Context));
end;
 
// ----------------------------------------------------------------------------------------------- 
 
// Create digest of given Message 
function MD5String(M: string): MD5Digest;
var 
  Context: MD5Context;
begin 
  MD5Init(Context);
  MD5Update(Context, pChar(M), length(M));
  MD5Final(Context, Result);
end; 
 
// Create digest of file with given Name 
function MD5File(N: string): MD5Digest; 
var 
  FileHandle: THandle;
  MapHandle: THandle;
  ViewPointer: pointer;
  Context: MD5Context;
begin 
  MD5Init(Context);
  FileHandle := CreateFile(pChar(N), GENERIC_READ, FILE_SHARE_READ or FILE_SHARE_WRITE,
  nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL or FILE_FLAG_SEQUENTIAL_SCAN, 0);
  if FileHandle <> INVALID_HANDLE_value then
  try
    MapHandle := CreateFileMapping(FileHandle, nil, PAGE_READONLY, 0, 0, nil);
    if MapHandle <> 0 then
    try
      ViewPointer := MapViewOfFile(MapHandle, FILE_MAP_READ, 0, 0, 0);
      if ViewPointer <> nil then
      try
        MD5Update(Context, ViewPointer, GetFileSize(FileHandle, nil));
      finally
        UnmapViewOfFile(ViewPointer);
      end;
    finally
      CloseHandle(MapHandle);
    end;
  finally
    CloseHandle(FileHandle);
  end;
  MD5Final(Context, Result);
end; 
 
// Create hex representation of given Digest 
function MD5Print(D: MD5Digest): string; 
var 
  I: byte;
const 
  Digits: array[0..15] of char =
  ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f');
begin 
  Result := '';
  for I := 0 to 15 do Result := Result + Digits[(D[I] shr 4) and $0f] + Digits[D[I] and $0f];
end;
 
// ----------------------------------------------------------------------------------------------- 
 
// Compare two Digests 
function MD5Match(D1, D2: MD5Digest): boolean; 
var 
  I: byte;
begin 
  I := 0;
  Result := TRUE;
  while Result and (I < 16) do
  begin
    Result := D1[I] = D2[I];
    inc(I);
  end;
end;
 


end.