www.pudn.com > Indy_9_00_14_src.zip > IdHashMessageDigest.pas


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{ $Log:  10183: IdHashMessageDigest.pas  
{ 
{   Rev 1.0    2002.11.12 10:40:22 PM  czhower 
} 
{ 
 
  Implementation of the MD2, MD4 and MD5 Message-Digest Algorithm 
  as specified in RFC 1319 (1115), 1320 (1186), 1321 
 (See NOTE below for details of what is exactly implemented) 
 
  Author: Pete Mee 
  Port to Indy 8.1 Doychin Bondzhev (doychin@dsoft-bg.com) 
  Copyright: (c) Chad Z. Hower and The Winshoes Working Group. 
 
  NOTE: 
  All MDx are ready and bug free. 
} 
 
unit IdHashMessageDigest; 
 
{ 
2002-Feb-07 Pete Me 
 - Fixed MD4 and MD5 for cases where n mod 512 = 448 where n is the number of 
    bits processed.  An extra zero byte was being added to the input which 
    offset the bit-size entry.  
2001-Oct-24 Pete Mee 
 - Fixed MD4 and MD5 for cases where n mod 512 >= 448 where n is the number of 
    bits processed.  This situation requires an additional block to be 
    processed. 
} 
 
interface 
 
uses 
  Classes, 
  IdGlobal, 
  IdHash; 
 
type 
  T16x4LongWordRecord = array[0..15] of LongWord; 
  T4x4x4LongWordRecord = array[0..3] of T4x4LongWordRecord; 
 
  T384BitRecord = array [0..47] of byte; 
  T128BitRecord = array [0..15] of byte; 
 
 
  TIdHashMessageDigest = class(TIdHash128); 
 
  TIdHashMessageDigest2 = class(TIdHashMessageDigest) 
  protected 
    FX: T384BitRecord; 
    FCBuffer: T128BitRecord; 
    FCheckSum: T128BitRecord; 
 
    procedure MDCoder; 
    procedure Reset; 
  public 
    function HashValue(AStream: TStream): T4x4LongWordRecord; override; 
  end; 
 
  TIdHashMessageDigest4 = class(TIdHashMessageDigest) 
  protected 
    FBuffer: T4x4LongWordRecord; 
    FCBuffer: T16x4LongWordRecord; 
 
    procedure MDCoder; virtual; 
 
    function func_f(x, y, z : LongWord) : LongWord; virtual; 
    function func_g(x, y, z : LongWord) : LongWord; virtual; 
    function func_h(x, y, z : LongWord) : LongWord; virtual; 
  public 
    function HashValue(AStream: TStream): T4x4LongWordRecord; override; 
  end; 
 
  TIdHashMessageDigest5 = class(TIdHashMessageDigest4) 
  protected 
    procedure MDCoder; override; 
 
    function func_g(x, y, z : LongWord) : LongWord; override; 
    function func_i(x, y, z : LongWord) : LongWord; virtual; 
  public 
 
  end; 
 
implementation 
 
{ TIdHashMessageDigest2 } 
 
const 
  MD2_PI_SUBST : array [0..255] of byte = ( 
     41,  46,  67, 201, 162, 216, 124,   1,  61,  54,  84, 161, 236, 240, 
      6,  19,  98, 167,   5, 243, 192, 199, 115, 140, 152, 147,  43, 217, 
    188,  76, 130, 202,  30, 155,  87,  60, 253, 212, 224,  22, 103,  66, 
    111,  24, 138,  23, 229,  18, 190,  78, 196, 214, 218, 158, 222,  73, 
    160, 251, 245, 142, 187,  47, 238, 122, 169, 104, 121, 145,  21, 178, 
      7,  63, 148, 194,  16, 137,  11,  34,  95,  33, 128, 127,  93, 154, 
     90, 144,  50,  39,  53,  62, 204, 231, 191, 247, 151,   3, 255,  25, 
     48, 179, 72, 165,  181, 209, 215,  94, 146,  42, 172,  86, 170, 198, 
     79, 184,  56, 210, 150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 
      4, 241,  69, 157, 112,  89, 100, 113, 135,  32, 134,  91, 207, 101, 
    230,  45, 168,   2,  27,  96,  37, 173, 174, 176, 185, 246,  28,  70, 
     97, 105,  52,  64, 126, 15,   85,  71, 163,  35, 221,  81, 175,  58, 
    195,  92, 249, 206, 186, 197, 234,  38,  44,  83,  13, 110, 133,  40, 
    132,   9, 211, 223, 205, 244, 65,  129,  77,  82, 106, 220,  55, 200, 
    108, 193, 171, 250,  36, 225, 123,   8,  12, 189, 177,  74, 120, 136, 
    149, 139, 227,  99, 232, 109, 233, 203, 213, 254,  59,   0,  29,  57, 
    242, 239, 183,  14, 102,  88, 208, 228, 166, 119, 114, 248, 235, 117, 
     75,  10,  49,  68,  80, 180, 143, 237,  31,  26, 219, 153, 141,  51, 
     159,  17, 131, 20); 
 
procedure TIdHashMessageDigest2.MDCoder; 
const 
  NumRounds = 18; 
Var 
  i, j: Byte; 
  T: Word; 
  LCheckSumScore: Byte; 
begin 
  // Move the next 16 bytes into the second 16 bytes of X. 
  Move(FCBuffer[0], FX[16], 16); 
  for i := 0 to 15 do 
  begin 
    FX[i + 32] := FCBuffer[i] xor FX[i]; 
  end; 
 
  { Do 18 rounds. } 
  T := 0; 
  for i := 0 to NumRounds - 1 do 
  begin 
    for j := 0 to 47 do 
    begin 
      T := FX[j] xor MD2_PI_SUBST[T]; 
      FX[j] := T and $FF; 
    end; 
    T := (T + i) and $FF; 
  end; 
 
  LCheckSumScore := FChecksum[15]; 
  for i := 0 to 15 do 
  begin 
    LCheckSumScore := FChecksum[i] xor MD2_PI_SUBST[FCBuffer[i] 
      xor LCheckSumScore]; 
    FChecksum[i] := LCheckSumScore; 
  end; 
end; 
 
// Clear Buffer and Checksum arrays 
procedure TIdHashMessageDigest2.Reset; 
begin 
  FillChar(FCheckSum[0], 16, 0); 
  FillChar(FCBuffer, 16, 0); 
  // Initialise the X buffer to zero. 
  FillChar(FX[0], 48, 0); 
end; 
 
function TIdHashMessageDigest2.HashValue(AStream: TStream): T4x4LongWordRecord; 
Var 
  LStartPos: Integer; 
  LSize: Int64; 
  S1: String; 
begin 
  Reset; 
 
  LStartPos := AStream.Position; 
  LSize := AStream.Size - LStartPos; 
 
  // Code the entire file in complete 16-byte chunks. 
  while LSize - AStream.Position >= SizeOf(FCBuffer) do 
  begin 
    AStream.Read(FCBuffer[0], SizeOf(FCBuffer)); 
    MDCoder; 
  end; 
 
  SetLength(S1, SizeOf(FCBuffer)); 
 
  LStartPos := AStream.Read(S1[1], 16); 
  // Step 1 
  FillChar(S1[LStartPos + 1], 16 - LStartPos, Byte(16 - LStartPos)); 
  Move(S1[1], FCBuffer[0], 16); 
  MDCoder; 
  // Step 2 
  Move(FCheckSUm[0], FCBuffer[0], 16); 
  MDCoder; 
 
  Move(FX[0], result[0], 16); 
end; 
 
{ TIdHashMessageDigest4 } 
 
const 
  MD4_INIT_VALUES: T4x4LongWordRecord = ( 
    $67452301, $EFCDAB89, $98BADCFE, $10325476); 
 
procedure TIdHashMessageDigest4.MDCoder; 
var 
  A, B, C, D, i : LongWord; 
  I64 : Int64; 
  buff : T4x4x4LongWordRecord; // 64-byte buffer 
 
  function DoAdd(const AOne, ATwo, AThree, AFour : LongWord) : LongWord; 
  begin 
    I64 := AOne; 
    I64 := ((I64 + ATwo) and $FFFFFFFF); 
    I64 := ((I64 + AThree) and $FFFFFFFF) + AFour; 
    result := I64 and $FFFFFFFF; 
  end; 
   
begin 
  A := FBuffer[0]; 
  B := FBuffer[1]; 
  C := FBuffer[2]; 
  D := FBuffer[3]; 
 
  System.Move(FCBuffer[0], buff[0], SizeOf(buff)); 
 
  // The following additions utilise Int64 to avoid integer overflow 
 
  // Round 1 
  for i := 0 to 3 do 
  begin  
    A := ROL(DoAdd(func_f(B, C, D), A, buff[i,0], 0), 3); 
    D := ROL(DoAdd(func_f(A, B, C), D, buff[i,1], 0), 7); 
    C := ROL(DoAdd(func_f(D, A, B), C, buff[i,2], 0), 11); 
    B := ROL(DoAdd(func_f(C, D, A), B, buff[i,3], 0), 19); 
  end; 
 
  // Round 2 
  for i := 0 to 3 do 
  begin 
    A := ROL(DoAdd(func_g(B, C, D), A, buff[0,i], $5A827999), 3); 
    D := ROL(DoAdd(func_g(A, B, C), D, buff[1,i], $5A827999), 5); 
    C := ROL(DoAdd(func_g(D, A, B), C, buff[2,i], $5A827999), 9); 
    B := ROL(DoAdd(func_g(C, D, A), B, buff[3,i], $5A827999), 13); 
  end; 
 
  // Round 3 
  A := ROL(DoAdd(func_h(B, C, D), A, T16x4LongWordRecord(buff)[0], $6ED9EBA1), 3); 
  D := ROL(DoAdd(func_h(A, B, C), D, T16x4LongWordRecord(buff)[8], $6ED9EBA1), 9); 
  C := ROL(DoAdd(func_h(D, A, B), C, T16x4LongWordRecord(buff)[4], $6ED9EBA1), 11); 
  B := ROL(DoAdd(func_h(C, D, A), B, T16x4LongWordRecord(buff)[12], $6ED9EBA1), 15); 
  A := ROL(DoAdd(func_h(B, C, D), A, T16x4LongWordRecord(buff)[2], $6ED9EBA1), 3); 
  D := ROL(DoAdd(func_h(A, B, C), D, T16x4LongWordRecord(buff)[10], $6ED9EBA1), 9); 
  C := ROL(DoAdd(func_h(D, A, B), C, T16x4LongWordRecord(buff)[6], $6ED9EBA1), 11); 
  B := ROL(DoAdd(func_h(C, D, A), B, T16x4LongWordRecord(buff)[14], $6ED9EBA1), 15); 
  A := ROL(DoAdd(func_h(B, C, D), A, T16x4LongWordRecord(buff)[1], $6ED9EBA1), 3); 
  D := ROL(DoAdd(func_h(A, B, C), D, T16x4LongWordRecord(buff)[9], $6ED9EBA1), 9); 
  C := ROL(DoAdd(func_h(D, A, B), C, T16x4LongWordRecord(buff)[5], $6ED9EBA1), 11); 
  B := ROL(DoAdd(func_h(C, D, A), B, T16x4LongWordRecord(buff)[13], $6ED9EBA1), 15); 
  A := ROL(DoAdd(func_h(B, C, D), A, T16x4LongWordRecord(buff)[3], $6ED9EBA1), 3); 
  D := ROL(DoAdd(func_h(A, B, C), D, T16x4LongWordRecord(buff)[11], $6ED9EBA1), 9); 
  C := ROL(DoAdd(func_h(D, A, B), C, T16x4LongWordRecord(buff)[7], $6ED9EBA1), 11); 
  B := ROL(DoAdd(func_h(C, D, A), B, T16x4LongWordRecord(buff)[15], $6ED9EBA1), 15); 
 
  I64 := FBuffer[0]; 
  Inc(I64, A); 
  FBuffer[0] := I64 and $FFFFFFFF; 
  I64 := FBuffer[1]; 
  Inc(I64, B); 
  FBuffer[1] := I64 and $FFFFFFFF; 
  I64 := FBuffer[2]; 
  Inc(I64, C); 
  FBuffer[2] := I64 and $FFFFFFFF; 
  I64 := FBuffer[3]; 
  Inc(I64, D); 
  FBuffer[3] := I64 and $FFFFFFFF; 
end; 
 
function TIdHashMessageDigest4.func_f(x, y, z : LongWord) : LongWord; 
begin 
  result := (x and y) or ( (not x) and z); 
end; 
 
function TIdHashMessageDigest4.func_g(x, y, z : LongWord) : LongWord; 
begin 
  result := (x and y) or (x and z) or (y and z); 
end; 
 
function TIdHashMessageDigest4.func_h(x, y, z : LongWord) : LongWord; 
begin 
  result := x xor y xor z; 
end; 
 
function TIdHashMessageDigest4.HashValue(AStream: TStream): T4x4LongWordRecord; 
Var 
  LStartPos: Integer; 
  LBitSize, 
  LSize: Int64; 
  S: String; 
  S1: String; 
  LFillSize : Integer; 
begin 
  LStartPos := AStream.Position; 
  LSize := AStream.Size - LStartPos; 
 
  FBuffer := MD4_INIT_VALUES; 
 
  while LSize - AStream.Position >= SizeOf(FCBuffer) do 
  begin 
    AStream.Read(FCBuffer[0], SizeOf(FCBuffer)); 
    MDCoder; 
  end; 
 
  // Ensure S1 has sufficient size to hold a complete 64-byte chunk 
  SetLength(S1, SizeOf(FCBuffer)); 
 
  // Read the last set of bytes. 
  LStartPos := AStream.Read(S1[1], 64); 
  // Now adjust S1 to only hold the last set of bytes. 
  SetLength(S1, LStartPos); 
  // Append one bit with value 1 
  S1 := S1 + Chr($80); 
 
  // Must have sufficient space to insert the 64-bit length 
  if Length(S1) > 64 - SizeOf(LSize) then 
  begin 
    SetLength(S, 64 - SizeOf(LSize)); 
    FillChar(S[1], 64 - SizeOf(LSize), #0); 
    S1 := S1 + S; 
    Move(S1[1], FCBuffer[0], SizeOf(FCBuffer)); 
    MDCoder; 
 
    // Create a new block with only zeros. 
    SetLength(S1, 64 - SizeOf(LSize)); 
    FillChar(S1[1], 64 - SizeOf(LSize), #0); 
  end else 
  begin 
    LFillSize := 64 - ((LSize + 9) mod 64); 
    // If the bit size will fit exact at the end (LFillSize = 64) 
    // then S1 need not be padded. 
    if LFillSize <> 64 then 
    begin 
      SetLength(S, LFillSize); 
      FillChar(S[1], LFillSize, #0); 
      S1 := S1 + S; // Extend the rest of the block with zeros 
    end; 
  end; 
 
  // Append the Number of bits processed. 
  LBitSize := LSize * 8; 
  Setlength(S, SizeOf(LBitSize)); 
  Move(LBitSize, S[1], SizeOf(LBitSize)); 
  S1 := S1 + S; // Append the stream size 
  Move(S1[1], FCBuffer[0], SizeOf(FCBuffer)); 
 
  MDCoder; 
 
  result := FBuffer; 
end; 
 
{ TIdHashMessageDigest5 } 
 
const 
  MD5_SINE : array [1..64] of LongWord = ( 
   { Round 1. } 
   $d76aa478, $e8c7b756, $242070db, $c1bdceee, $f57c0faf, $4787c62a, 
   $a8304613, $fd469501, $698098d8, $8b44f7af, $ffff5bb1, $895cd7be, 
   $6b901122, $fd987193, $a679438e, $49b40821, 
   { Round 2. } 
   $f61e2562, $c040b340, $265e5a51, $e9b6c7aa, $d62f105d, $02441453, 
   $d8a1e681, $e7d3fbc8, $21e1cde6, $c33707d6, $f4d50d87, $455a14ed, 
   $a9e3e905, $fcefa3f8, $676f02d9, $8d2a4c8a, 
   { Round 3. } 
   $fffa3942, $8771f681, $6d9d6122, $fde5380c, $a4beea44, $4bdecfa9, 
   $f6bb4b60, $bebfbc70, $289b7ec6, $eaa127fa, $d4ef3085, $04881d05, 
   $d9d4d039, $e6db99e5, $1fa27cf8, $c4ac5665, 
   { Round 4. } 
   $f4292244, $432aff97, $ab9423a7, $fc93a039, $655b59c3, $8f0ccc92, 
   $ffeff47d, $85845dd1, $6fa87e4f, $fe2ce6e0, $a3014314, $4e0811a1, 
   $f7537e82, $bd3af235, $2ad7d2bb, $eb86d391 
  ); 
 
procedure TIdHashMessageDigest5.MDCoder; 
var 
  A, B, C, D : LongWord; 
  I64 : Int64; 
  x : T16x4LongWordRecord; // 64-byte buffer 
 
  function DoAdd(const AOne, ATwo, AThree, AFour, AFive, AROL 
    : LongWord) : LongWord; 
  begin 
    I64 := ATwo; 
    I64 := I64 + AThree + AFour + AFive; 
    I64 := ROL(I64 and $FFFFFFFF, AROL); 
    Inc(I64, AOne); 
    result := I64 and $FFFFFFFF; 
  end; 
begin 
  A := FBuffer[0]; 
  B := FBuffer[1]; 
  C := FBuffer[2]; 
  D := FBuffer[3]; 
 
  System.Move(FCBuffer[0], x[0], SizeOf(x)); 
 
  { Round 1 } 
  A := DoAdd(B, A, func_f(B, C, D), x[0], MD5_SINE[1], 7); 
  D := DoAdd(A, D, func_f(A, B, C), x[1], MD5_SINE[2], 12); 
  C := DoAdd(D, C, func_f(D, A, B), x[2], MD5_SINE[3], 17); 
  B := DoAdd(C, B, func_f(C, D, A), x[3], MD5_SINE[4], 22); 
  A := DoAdd(B, A, func_f(B, C, D), x[4], MD5_SINE[5], 7); 
  D := DoAdd(A, D, func_f(A, B, C), x[5], MD5_SINE[6], 12); 
  C := DoAdd(D, C, func_f(D, A, B), x[6], MD5_SINE[7], 17); 
  B := DoAdd(C, B, func_f(C, D, A), x[7], MD5_SINE[8], 22); 
  A := DoAdd(B, A, func_f(B, C, D), x[8], MD5_SINE[9], 7); 
  D := DoAdd(A, D, func_f(A, B, C), x[9], MD5_SINE[10], 12); 
  C := DoAdd(D, C, func_f(D, A, B), x[10], MD5_SINE[11], 17); 
  B := DoAdd(C, B, func_f(C, D, A), x[11], MD5_SINE[12], 22); 
  A := DoAdd(B, A, func_f(B, C, D), x[12], MD5_SINE[13], 7); 
  D := DoAdd(A, D, func_f(A, B, C), x[13], MD5_SINE[14], 12); 
  C := DoAdd(D, C, func_f(D, A, B), x[14], MD5_SINE[15], 17); 
  B := DoAdd(C, B, func_f(C, D, A), x[15], MD5_SINE[16], 22); 
 
  { Round 2 } 
  A := DoAdd(B, A, func_g(B, C, D), x[1], MD5_SINE[17], 5); 
  D := DoAdd(A, D, func_g(A, B, C), x[6], MD5_SINE[18], 9); 
  C := DoAdd(D, C, func_g(D, A, B), x[11], MD5_SINE[19], 14); 
  B := DoAdd(C, B, func_g(C, D, A), x[0], MD5_SINE[20], 20); 
  A := DoAdd(B, A, func_g(B, C, D), x[5], MD5_SINE[21], 5); 
  D := DoAdd(A, D, func_g(A, B, C), x[10], MD5_SINE[22], 9); 
  C := DoAdd(D, C, func_g(D, A, B), x[15], MD5_SINE[23], 14); 
  B := DoAdd(C, B, func_g(C, D, A), x[4], MD5_SINE[24], 20); 
  A := DoAdd(B, A, func_g(B, C, D), x[9], MD5_SINE[25], 5); 
  D := DoAdd(A, D, func_g(A, B, C), x[14], MD5_SINE[26], 9); 
  C := DoAdd(D, C, func_g(D, A, B), x[3], MD5_SINE[27], 14); 
  B := DoAdd(C, B, func_g(C, D, A), x[8], MD5_SINE[28], 20); 
  A := DoAdd(B, A, func_g(B, C, D), x[13], MD5_SINE[29], 5); 
  D := DoAdd(A, D, func_g(A, B, C), x[2], MD5_SINE[30], 9); 
  C := DoAdd(D, C, func_g(D, A, B), x[7], MD5_SINE[31], 14); 
  B := DoAdd(C, B, func_g(C, D, A), x[12], MD5_SINE[32], 20); 
 
  { Round 3. } 
  A := DoAdd(B, A, func_h(B, C, D), x[5], MD5_SINE[33], 4); 
  D := DoAdd(A, D, func_h(A, B, C), x[8], MD5_SINE[34], 11); 
  C := DoAdd(D, C, func_h(D, A, B), x[11], MD5_SINE[35], 16); 
  B := DoAdd(C, B, func_h(C, D, A), x[14], MD5_SINE[36], 23); 
  A := DoAdd(B, A, func_h(B, C, D), x[1], MD5_SINE[37], 4); 
  D := DoAdd(A, D, func_h(A, B, C), x[4], MD5_SINE[38], 11); 
  C := DoAdd(D, C, func_h(D, A, B), x[7], MD5_SINE[39], 16); 
  B := DoAdd(C, B, func_h(C, D, A), x[10], MD5_SINE[40], 23); 
  A := DoAdd(B, A, func_h(B, C, D), x[13], MD5_SINE[41], 4); 
  D := DoAdd(A, D, func_h(A, B, C), x[0], MD5_SINE[42], 11); 
  C := DoAdd(D, C, func_h(D, A, B), x[3], MD5_SINE[43], 16); 
  B := DoAdd(C, B, func_h(C, D, A), x[6], MD5_SINE[44], 23); 
  A := DoAdd(B, A, func_h(B, C, D), x[9], MD5_SINE[45], 4); 
  D := DoAdd(A, D, func_h(A, B, C), x[12], MD5_SINE[46], 11); 
  C := DoAdd(D, C, func_h(D, A, B), x[15], MD5_SINE[47], 16); 
  B := DoAdd(C, B, func_h(C, D, A), x[2], MD5_SINE[48], 23); 
 
  { Round 4. } 
  A := DoAdd(B, A, func_i(B, C, D), x[0], MD5_SINE[49], 6); 
  D := DoAdd(A, D, func_i(A, B, C), x[7], MD5_SINE[50], 10); 
  C := DoAdd(D, C, func_i(D, A, B), x[14], MD5_SINE[51], 15); 
  B := DoAdd(C, B, func_i(C, D, A), x[5], MD5_SINE[52], 21); 
  A := DoAdd(B, A, func_i(B, C, D), x[12], MD5_SINE[53], 6); 
  D := DoAdd(A, D, func_i(A, B, C), x[3], MD5_SINE[54], 10); 
  C := DoAdd(D, C, func_i(D, A, B), x[10], MD5_SINE[55], 15); 
  B := DoAdd(C, B, func_i(C, D, A), x[1], MD5_SINE[56], 21); 
  A := DoAdd(B, A, func_i(B, C, D), x[8], MD5_SINE[57], 6); 
  D := DoAdd(A, D, func_i(A, B, C), x[15], MD5_SINE[58], 10); 
  C := DoAdd(D, C, func_i(D, A, B), x[6], MD5_SINE[59], 15); 
  B := DoAdd(C, B, func_i(C, D, A), x[13], MD5_SINE[60], 21); 
  A := DoAdd(B, A, func_i(B, C, D), x[4], MD5_SINE[61], 6); 
  D := DoAdd(A, D, func_i(A, B, C), x[11], MD5_SINE[62], 10); 
  C := DoAdd(D, C, func_i(D, A, B), x[2], MD5_SINE[63], 15); 
  B := DoAdd(C, B, func_i(C, D, A), x[9], MD5_SINE[64], 21); 
 
  I64 := FBuffer[0]; 
  Inc(I64, A); 
  FBuffer[0] := I64 and $FFFFFFFF; 
  I64 := FBuffer[1]; 
  Inc(I64, B); 
  FBuffer[1] := I64 and $FFFFFFFF; 
  I64 := FBuffer[2]; 
  Inc(I64, C); 
  FBuffer[2] := I64 and $FFFFFFFF; 
  I64 := FBuffer[3]; 
  Inc(I64, D); 
  FBuffer[3] := I64 and $FFFFFFFF; 
end; 
 
function TIdHashMessageDigest5.func_g(x, y, z : LongWord) : LongWord; 
begin 
  result := (x and z) or (y and (not z)); 
end; 
 
function TIdHashMessageDigest5.func_i(x, y, z : LongWord) : LongWord; 
begin 
  result := y xor (x or (not z)); 
end; 
 
end.