// -----------------------------------------------------------------------------------------------
//
//                                 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.

