For i:=1 to length(str) do str[i]:=chr(ord(str[i]) xor key);

{ Вычисление хеш-суммы MD5 }

unit UMD5;

interface

uses Windows, SysUtils, Classes;

type
  { Тип TMD5Digest используется для получения
    результата функций вычисления хеш-суммы.
    Содержимое записи можно использовать
    как набор из 4 целых чисел, или как
    массив из 16 байт }
  PMD5Digest = ^TMD5Digest;
  TMD5Digest = record
    case Integer of
      0: (A, B, C, D: LongInt);
      1: (v: array[0..15] of Byte);
  end;

  // вычисление хеш-суммы для строки
function MD5String(const S: string): TMD5Digest;

// вычисление хеш-суммы для файла
function MD5File(const FileName: string): TMD5Digest;

// вычисление хеш-суммы для содержиого потока Stream
function MD5Stream(const Stream: TStream): TMD5Digest;

// вычисление хеш-суммы для произвольного буфера
function MD5Buffer(const Buffer; Size: Integer): TMD5Digest;

// преобразование хеш-суммы в строку из шестнадцатеричных цифр
function MD5DigestToStr(const Digest: TMD5Digest): string;

// сравнение двух хеш-сумм
function MD5DigestCompare(const Digest1, Digest2: TMD5Digest): Boolean;

implementation

type
  UINT4 = LongWord;

  PArray4UINT4 = ^TArray4UINT4;
  TArray4UINT4 = array[0..3] of UINT4;
  PArray2UINT4 = ^TArray2UINT4;
  TArray2UINT4 = array[0..1] of UINT4;
  PArray16Byte = ^TArray16Byte;
  TArray16Byte = array[0..15] of Byte;
  PArray64Byte = ^TArray64Byte;
  TArray64Byte = array[0..63] of Byte;

  PByteArray = ^TByteArray;
  TByteArray = array[0..0] of Byte;

  PUINT4Array = ^TUINT4Array;
  TUINT4Array = array[0..0] of UINT4;

  PMD5Context = ^TMD5Context;
  TMD5Context = record
    state: TArray4UINT4;
    count: TArray2UINT4;
    buffer: TArray64Byte;
  end;

const
  S11 = 7;
  S12 = 12;
  S13 = 17;
  S14 = 22;
  S21 = 5;
  S22 = 9;
  S23 = 14;
  S24 = 20;
  S31 = 4;
  S32 = 11;
  S33 = 16;
  S34 = 23;
  S41 = 6;
  S42 = 10;
  S43 = 15;
  S44 = 21;

var
  Padding: TArray64Byte =
  ($80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

function _F(x, y, z: UINT4): UINT4;
begin
  Result := (((x) and (y)) or ((not x) and (z)));
end;

function _G(x, y, z: UINT4): UINT4;
begin
  Result := (((x) and (z)) or ((y) and (not z)));
end;

function _H(x, y, z: UINT4): UINT4;
begin
  Result := ((x) xor (y) xor (z));
end;

function _I(x, y, z: UINT4): UINT4;
begin
  Result := ((y) xor ((x) or (not z)));
end;

function ROTATE_LEFT(x, n: UINT4): UINT4;
begin
  Result := (((x) shl (n)) or ((x) shr (32 - (n))));
end;

procedure FF(var a: UINT4; b, c, d, x, s, ac: UINT4);
begin
  a := a + _F(b, c, d) + x + ac;
  a := ROTATE_LEFT(a, s);
  a := a + b;
end;

procedure GG(var a: UINT4; b, c, d, x, s, ac: UINT4);
begin
  a := a + _G(b, c, d) + x + ac;
  a := ROTATE_LEFT(a, s);
  a := a + b;
end;

procedure HH(var a: UINT4; b, c, d, x, s, ac: UINT4);
begin
  a := a + _H(b, c, d) + x + ac;
  a := ROTATE_LEFT(a, s);
  a := a + b;
end;

procedure II(var a: UINT4; b, c, d, x, s, ac: UINT4);
begin
  a := a + _I(b, c, d) + x + ac;
  a := ROTATE_LEFT(a, s);
  a := a + b;
end;

procedure MD5Encode(Output: PByteArray; Input: PUINT4Array; Len: LongWord);
var
  i, j: LongWord;
begin
  j := 0;
  i := 0;
  while j < Len do
  begin
    output[j] := Byte(input[i] and $FF);
    output[j + 1] := Byte((input[i] shr 8) and $FF);
    output[j + 2] := Byte((input[i] shr 16) and $FF);
    output[j + 3] := Byte((input[i] shr 24) and $FF);
    Inc(j, 4);
    Inc(i);
  end;
end;

procedure MD5Decode(Output: PUINT4Array; Input: PByteArray; Len: LongWord);
var
  i, j: LongWord;
begin
  j := 0;
  i := 0;
  while j < Len do
  begin
    Output[i] := UINT4(input[j]) or (UINT4(input[j + 1]) shl 8) or
      (UINT4(input[j + 2]) shl 16) or (UINT4(input[j + 3]) shl 24);
    Inc(j, 4);
    Inc(i);
  end;
end;

procedure MD5_memcpy(Output: PByteArray; Input: PByteArray; Len: LongWord);
begin
  Move(Input^, Output^, Len);
end;

procedure MD5_memset(Output: PByteArray; Value: Integer; Len: LongWord);
begin
  FillChar(Output^, Len, Byte(Value));
end;

procedure MD5Transform(State: PArray4UINT4; Buffer: PArray64Byte);
var
  a, b, c, d: UINT4;
  x: array[0..15] of UINT4;
begin
  a := State[0];
  b := State[1];
  c := State[2];
  d := State[3];
  MD5Decode(PUINT4Array(@x), PByteArray(Buffer), 64);

  FF(a, b, c, d, x[0], S11, $D76AA478);
  FF(d, a, b, c, x[1], S12, $E8C7B756);
  FF(c, d, a, b, x[2], S13, $242070DB);
  FF(b, c, d, a, x[3], S14, $C1BDCEEE);
  FF(a, b, c, d, x[4], S11, $F57C0FAF);
  FF(d, a, b, c, x[5], S12, $4787C62A);
  FF(c, d, a, b, x[6], S13, $A8304613);
  FF(b, c, d, a, x[7], S14, $FD469501);
  FF(a, b, c, d, x[8], S11, $698098D8);
  FF(d, a, b, c, x[9], S12, $8B44F7AF);
  FF(c, d, a, b, x[10], S13, $FFFF5BB1);
  FF(b, c, d, a, x[11], S14, $895CD7BE);
  FF(a, b, c, d, x[12], S11, $6B901122);
  FF(d, a, b, c, x[13], S12, $FD987193);
  FF(c, d, a, b, x[14], S13, $A679438E);
  FF(b, c, d, a, x[15], S14, $49B40821);

  GG(a, b, c, d, x[1], S21, $F61E2562);
  GG(d, a, b, c, x[6], S22, $C040B340);
  GG(c, d, a, b, x[11], S23, $265E5A51);
  GG(b, c, d, a, x[0], S24, $E9B6C7AA);
  GG(a, b, c, d, x[5], S21, $D62F105D);
  GG(d, a, b, c, x[10], S22, $2441453);
  GG(c, d, a, b, x[15], S23, $D8A1E681);
  GG(b, c, d, a, x[4], S24, $E7D3FBC8);
  GG(a, b, c, d, x[9], S21, $21E1CDE6);
  GG(d, a, b, c, x[14], S22, $C33707D6);
  GG(c, d, a, b, x[3], S23, $F4D50D87);

  GG(b, c, d, a, x[8], S24, $455A14ED);
  GG(a, b, c, d, x[13], S21, $A9E3E905);
  GG(d, a, b, c, x[2], S22, $FCEFA3F8);
  GG(c, d, a, b, x[7], S23, $676F02D9);
  GG(b, c, d, a, x[12], S24, $8D2A4C8A);

  HH(a, b, c, d, x[5], S31, $FFFA3942);
  HH(d, a, b, c, x[8], S32, $8771F681);
  HH(c, d, a, b, x[11], S33, $6D9D6122);
  HH(b, c, d, a, x[14], S34, $FDE5380C);
  HH(a, b, c, d, x[1], S31, $A4BEEA44);
  HH(d, a, b, c, x[4], S32, $4BDECFA9);
  HH(c, d, a, b, x[7], S33, $F6BB4B60);
  HH(b, c, d, a, x[10], S34, $BEBFBC70);
  HH(a, b, c, d, x[13], S31, $289B7EC6);
  HH(d, a, b, c, x[0], S32, $EAA127FA);
  HH(c, d, a, b, x[3], S33, $D4EF3085);
  HH(b, c, d, a, x[6], S34, $4881D05);
  HH(a, b, c, d, x[9], S31, $D9D4D039);
  HH(d, a, b, c, x[12], S32, $E6DB99E5);
  HH(c, d, a, b, x[15], S33, $1FA27CF8);
  HH(b, c, d, a, x[2], S34, $C4AC5665);

  II(a, b, c, d, x[0], S41, $F4292244);
  II(d, a, b, c, x[7], S42, $432AFF97);
  II(c, d, a, b, x[14], S43, $AB9423A7);
  II(b, c, d, a, x[5], S44, $FC93A039);
  II(a, b, c, d, x[12], S41, $655B59C3);
  II(d, a, b, c, x[3], S42, $8F0CCC92);
  II(c, d, a, b, x[10], S43, $FFEFF47D);
  II(b, c, d, a, x[1], S44, $85845DD1);
  II(a, b, c, d, x[8], S41, $6FA87E4F);
  II(d, a, b, c, x[15], S42, $FE2CE6E0);
  II(c, d, a, b, x[6], S43, $A3014314);
  II(b, c, d, a, x[13], S44, $4E0811A1);
  II(a, b, c, d, x[4], S41, $F7537E82);
  II(d, a, b, c, x[11], S42, $BD3AF235);
  II(c, d, a, b, x[2], S43, $2AD7D2BB);
  II(b, c, d, a, x[9], S44, $EB86D391);

  Inc(State[0], a);
  Inc(State[1], b);
  Inc(State[2], c);
  Inc(State[3], d);

  MD5_memset(PByteArray(@x), 0, SizeOf(x));
end;

procedure MD5Init(var Context: TMD5Context);
begin
  FillChar(Context, SizeOf(Context), 0);
  Context.state[0] := $67452301;
  Context.state[1] := $EFCDAB89;
  Context.state[2] := $98BADCFE;
  Context.state[3] := $10325476;
end;

procedure MD5Update(var Context: TMD5Context; Input: PByteArray; InputLen:
  LongWord);
var
  i, index, partLen: LongWord;

begin
  index := LongWord((context.count[0] shr 3) and $3F);
  Inc(Context.count[0], UINT4(InputLen) shl 3);
  if Context.count[0] < UINT4(InputLen) shl 3 then
    Inc(Context.count[1]);
  Inc(Context.count[1], UINT4(InputLen) shr 29);
  partLen := 64 - index;
  if inputLen >= partLen then
  begin
    MD5_memcpy(PByteArray(@Context.buffer[index]), Input, PartLen);
    MD5Transform(@Context.state, @Context.buffer);
    i := partLen;
    while i + 63 < inputLen do
    begin
      MD5Transform(@Context.state, PArray64Byte(@Input[i]));
      Inc(i, 64);
    end;
    index := 0;
  end
  else
    i := 0;
  MD5_memcpy(PByteArray(@Context.buffer[index]), PByteArray(@Input[i]), inputLen
    - i);
end;

procedure MD5Final(var Digest: TMD5Digest; var Context: TMD5Context);
var
  bits: array[0..7] of Byte;
  index, padLen: LongWord;
begin
  MD5Encode(PByteArray(@bits), PUINT4Array(@Context.count), 8);
  index := LongWord((Context.count[0] shr 3) and $3F);
  if index < 56 then
    padLen := 56 - index
  else
    padLen := 120 - index;
  MD5Update(Context, PByteArray(@PADDING), padLen);
  MD5Update(Context, PByteArray(@Bits), 8);
  MD5Encode(PByteArray(@Digest), PUINT4Array(@Context.state), 16);
  MD5_memset(PByteArray(@Context), 0, SizeOf(Context));
end;

function MD5DigestToStr(const Digest: TMD5Digest): string;
var
  i: Integer;
begin
  Result := '';
  for i := 0 to 15 do
    Result := Result + IntToHex(Digest.v[i], 2);
end;

function MD5String(const S: string): TMD5Digest;
begin
  Result := MD5Buffer(PChar(S)^, Length(S));
end;

function MD5File(const FileName: string): TMD5Digest;
var
  F: TFileStream;
begin
  F := TFileStream.Create(FileName, fmOpenRead);
  try
    Result := MD5Stream(F);
  finally
    F.Free;
  end;
end;

function MD5Stream(const Stream: TStream): TMD5Digest;
var
  Context: TMD5Context;
  Buffer: array[0..4095] of Byte;
  Size: Integer;
  ReadBytes: Integer;
  TotalBytes: Integer;
  SavePos: Integer;
begin
  MD5Init(Context);
  Size := Stream.Size;
  SavePos := Stream.Position;
  TotalBytes := 0;
  try
    Stream.Seek(0, soFromBeginning);
    repeat
      ReadBytes := Stream.Read(Buffer, SizeOf(Buffer));
      Inc(TotalBytes, ReadBytes);
      MD5Update(Context, @Buffer, ReadBytes);
    until (ReadBytes = 0) or (TotalBytes = Size);
  finally
    Stream.Seek(SavePos, soFromBeginning);
  end;
  MD5Final(Result, Context);
end;

function MD5Buffer(const Buffer; Size: Integer): TMD5Digest;
var
  Context: TMD5Context;
begin
  MD5Init(Context);
  MD5Update(Context, PByteArray(@Buffer), Size);
  MD5Final(Result, Context);
end;

function MD5DigestCompare(const Digest1, Digest2: TMD5Digest): Boolean;
begin
  Result := False;
  if Digest1.A <> Digest2.A then
    Exit;
  if Digest1.B <> Digest2.B then
    Exit;
  if Digest1.C <> Digest2.C then
    Exit;
  if Digest1.D <> Digest2.D then
    Exit;
  Result := True;
end;

end.