// tabs = 2
// -----------------------------------------------------------------------------------------------

//                                 MD5 Message-Digest for Delphi 4

 //                                 Delphi 4 Unit implementing the
 //                      RSA Data Security, Inc. MD5 Message-Digest Algorithm

//                          Implementation of Ronald L. Rivest's RFC 1321

 //                      Copyright © 1997-1999 Medienagentur Fichtner & Meyer
 //                                  Written by Matthias Fichtner

// -----------------------------------------------------------------------------------------------
//               See RFC 1321 for RSA Data Security's copyright and license notice!
// -----------------------------------------------------------------------------------------------

//     14-Jun-97  mf  Implemented MD5 according to RFC 1321                           RFC 1321
//     16-Jun-97  mf  Initial release of the compiled unit (no source code)           RFC 1321
//     28-Feb-99  mf  Added MD5Match function for comparing two digests               RFC 1321
//     13-Sep-99  mf  Reworked the entire unit                                        RFC 1321
//     17-Sep-99  mf  Reworked the "Test Driver" project                              RFC 1321
//     19-Sep-99  mf  Release of sources for MD5 unit and "Test Driver" project       RFC 1321

// -----------------------------------------------------------------------------------------------
 //                   The latest release of md5.pas will always be available from
 //                  the distribution site at: http://www.fichtner.net/delphi/md5/
// -----------------------------------------------------------------------------------------------
 //                       Please send questions, bug reports and suggestions
 //                      regarding this code to: mfichtner@fichtner-meyer.com
// -----------------------------------------------------------------------------------------------
 //                        This code is provided "as is" without express or
 //                     implied warranty of any kind. Use it at your own risk.
// -----------------------------------------------------------------------------------------------

unit md5;

// -----------------------------------------------------------------------------------------------
interface
// -----------------------------------------------------------------------------------------------

uses
  Windows;

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;

// -----------------------------------------------------------------------------------------------

// Encode Count bytes at Source into (Count / 4) DWORDs at Target
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;

// Decode Count DWORDs at Source into (Count * 4) Bytes at Target
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;

// -----------------------------------------------------------------------------------------------

// Initialize given Context
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;

// 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.

