interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

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: PAnsiChar;
Length: longword);
procedure MD5Final(var Context: MD5Context; var Digest: MD5Digest);
function MD5File(N: String): MD5Digest;
function MD5Print(D: MD5Digest): AnsiString;
function MD5F(FileName: AnsiString): AnsiString;
function MD5S(Str: AnsiString): AnsiString;

// MD5F為計算文件的MD5值,MD5S為計算字符串的MD5值!
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);

implementation

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;

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;

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;

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;

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;

procedure MD5Update(var Context: MD5Context; Input: PAnsiChar;
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;

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;

function MD5String(M: AnsiString): MD5Digest;
var
Context: MD5Context;
begin
MD5Init(Context);
MD5Update(Context, PAnsiChar(M), Length(M));
MD5Final(Context, Result);
end;

function MD5File(N: String): MD5Digest;
var
FileHandle: THandle;
MapHandle: THandle;
ViewPointer: pointer;
Context: MD5Context;
begin
MD5Init(Context);
FileHandle := CreateFile(PWideChar(WideString(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;

function MD5Print(D: MD5Digest): AnsiString;
var
I: Byte;
const
Digits: array [0 .. 15] of Ansichar = ('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;

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;

function MD5S(Str: AnsiString): AnsiString;
begin
Result := MD5Print(MD5String(Str));
end;

function MD5F(FileName: AnsiString): AnsiString;
begin
Result := MD5Print(MD5File(string(FileName)));
end;