Документация по криптоалгоритмам / The MD5 Algorithm Specification and Source (eng - txt) / pas / MD5

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Author: Franзois PIETTE. Based on work given by Louis S. Berman from
BrainTree Ltd, lsb@braintree.com
Description: MD5 is an implmentation for the MD5 Message-Digest Algorithm
as described in RFC-1321
EMail: francois.piette@ping.be http://www.rtfm.be/fpiette
francois.piette@f2202.n293.z2.fidonet.org
2:293/2202@fidonet.org, BBS +32-4-3651395
Creation: October 11, 1997
Version: 1.00
WebSite: http://www.rtfm.be/fpiette/indexuk.htm
Support: Use the mailing list twsocket@rtfm.be See website for details.
Legal issues: Copyright (C) 1997 by Franзois PIETTE <francois.piette@ping.be>

This software is provided 'as-is', without any express or
implied warranty. In no event will the author be held liable
for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any
purpose, including commercial applications, and to alter it
and redistribute it freely, subject to the following
restrictions:

1. The origin of this software must not be misrepresented,
you must not claim that you wrote the original software.
If you use this software in a product, an acknowledgment
in the product documentation would be appreciated but is
not required.

2. Altered source versions must be plainly marked as such, and
must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source
distribution.

Updates:
Oct 26, 1997 Changed MD5Final form function to procedure to be compatible
with C++Builder.

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unit MD5;

interface

uses
SysUtils;

const
MD5Version = 100;

type
TMD5Context = record
State: array[0..3] of LongInt;
Count: array[0..1] of LongInt;
case Integer of
0: (BufChar: array[0..63] of Byte);
1: (BufLong: array[0..15] of LongInt);
end;
TMD5Digest = array[0..15] of Char;

procedure MD5Init(var MD5Context: TMD5Context);
procedure MD5Update(var MD5Context: TMD5Context;
const Data;
Len: Integer);
procedure MD5Transform(var Buf: array of LongInt;
const Data: array of LongInt);
procedure MD5UpdateBuffer(var MD5Context: TMD5Context;
Buffer: Pointer;
BufSize: Integer);
procedure MD5Final(var Digest: TMD5Digest; var MD5Context: TMD5Context);

function GetMD5(Buffer: Pointer; BufSize: Integer): string;
function StrMD5(Buffer : String): string;

implementation

const
MaxBufSize = 16384;

type
PMD5Buffer = ^TMD5Buffer;
TMD5Buffer = array[0..(MaxBufSize - 1)] of Char;



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{ MD5 initialization. Begins an MD5 operation, writing a new context. }
procedure MD5Init(var MD5Context: TMD5Context);
begin
FillChar(MD5Context, SizeOf(TMD5Context), #0);
with MD5Context do begin
{ Load magic initialization constants. }
State[0] := $67452301;
State[1] := $EFCDAB89;
State[2] := $98BADCFE;
State[3] := $10325476
end
end;


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{ MD5 block update operation. Continues an MD5 message-digest operation, }
{ processing another message block, and updating the context. }
procedure MD5Update(
var MD5Context: TMD5Context; { Context }
const Data; { Input block }
Len: Integer); { Length of input block }
type
TByteArray = array[0..0] of Byte;
var
Index: Word;
T: LongInt;
begin
with MD5Context do begin
T := Count[0];
Inc(Count[0], LongInt(Len) shl 3);
if Count[0] < T then
Inc(Count[1]);
Inc(Count[1], Len shr 29);
T := (T shr 3) and $3F;
Index := 0;
if T <> 0 then begin
Index := T;
T := 64 - T;
if Len < T then begin
Move(Data, BufChar[Index], Len);
Exit;
end;
Move(Data, BufChar[Index], T);
MD5Transform(State, BufLong);
Dec(Len, T);
end;
while Len >= 64 do begin
Move(TByteArray(Data)[Index], BufChar, 64);
MD5Transform(State, BufLong);
Inc(Index, 64);
Dec(Len, 64);
end;
Move(TByteArray(Data)[Index], BufChar, Len);
end
end;


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{ MD5 finalization. Ends an MD5 message-digest operation, writing the message }
{ digest and zeroizing the context. }
procedure MD5Final(var Digest: TMD5Digest; var MD5Context: TMD5Context);
var
Cnt : Word;
P : Byte;
begin
with MD5Context do begin
Cnt := (Count[0] shr 3) and $3F;
P := Cnt;
BufChar[P] := $80;
Inc(P);
Cnt := 64 - 1 - Cnt;
if Cnt < 8 then begin
FillChar(BufChar[P], Cnt, #0);
MD5Transform(State, BufLong);
FillChar(BufChar, 56, #0);
end
else
FillChar(BufChar[P], Cnt - 8, #0);
BufLong[14] := Count[0];
BufLong[15] := Count[1];
MD5Transform(State, BufLong);
Move(State, Digest, 16)
end;
FillChar(MD5Context, SizeOf(TMD5Context), #0)
end;


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{ MD5 basic transformation. Transforms state based on block. }
procedure MD5Transform(
var Buf: array of LongInt;
const Data: array of LongInt);
var
A, B, C, D: LongInt;

procedure Round1(var W: LongInt; X, Y, Z, Data: LongInt; S: Byte);
begin
Inc(W, (Z xor (X and (Y xor Z))) + Data);
W := (W shl S) or (W shr (32 - S));
Inc(W, X)
end;

procedure Round2(var W: LongInt; X, Y, Z, Data: LongInt; S: Byte);
begin
Inc(W, (Y xor (Z and (X xor Y))) + Data);
W := (W shl S) or (W shr (32 - S));
Inc(W, X)
end;

procedure Round3(var W: LongInt; X, Y, Z, Data: LongInt; S: Byte);
begin
Inc(W, (X xor Y xor Z) + Data);
W := (W shl S) or (W shr (32 - S));
Inc(W, X)
end;

procedure Round4(var W: LongInt; X, Y, Z, Data: LongInt; S: Byte);
begin
Inc(W, (Y xor (X or not Z)) + Data);
W := (W shl S) or (W shr (32 - S));
Inc(W, X)
end;
begin
A := Buf[0];
B := Buf[1];
C := Buf[2];
D := Buf[3];

Round1(A, B, C, D, Data[ 0] + $d76aa478, 7);
Round1(D, A, B, C, Data[ 1] + $e8c7b756, 12);
Round1(C, D, A, B, Data[ 2] + $242070db, 17);
Round1(B, C, D, A, Data[ 3] + $c1bdceee, 22);
Round1(A, B, C, D, Data[ 4] + $f57c0faf, 7);
Round1(D, A, B, C, Data[ 5] + $4787c62a, 12);
Round1(C, D, A, B, Data[ 6] + $a8304613, 17);
Round1(B, C, D, A, Data[ 7] + $fd469501, 22);
Round1(A, B, C, D, Data[ 8] + $698098d8, 7);
Round1(D, A, B, C, Data[ 9] + $8b44f7af, 12);
Round1(C, D, A, B, Data[10] + $ffff5bb1, 17);
Round1(B, C, D, A, Data[11] + $895cd7be, 22);
Round1(A, B, C, D, Data[12] + $6b901122, 7);
Round1(D, A, B, C, Data[13] + $fd987193, 12);
Round1(C, D, A, B, Data[14] + $a679438e, 17);
Round1(B, C, D, A, Data[15] + $49b40821, 22);

Round2(A, B, C, D, Data[ 1] + $f61e2562, 5);
Round2(D, A, B, C, Data[ 6] + $c040b340, 9);
Round2(C, D, A, B, Data[11] + $265e5a51, 14);
Round2(B, C, D, A, Data[ 0] + $e9b6c7aa, 20);
Round2(A, B, C, D, Data[ 5] + $d62f105d, 5);
Round2(D, A, B, C, Data[10] + $02441453, 9);
Round2(C, D, A, B, Data[15] + $d8a1e681, 14);
Round2(B, C, D, A, Data[ 4] + $e7d3fbc8, 20);
Round2(A, B, C, D, Data[ 9] + $21e1cde6, 5);
Round2(D, A, B, C, Data[14] + $c33707d6, 9);
Round2(C, D, A, B, Data[ 3] + $f4d50d87, 14);
Round2(B, C, D, A, Data[ 8] + $455a14ed, 20);
Round2(A, B, C, D, Data[13] + $a9e3e905, 5);
Round2(D, A, B, C, Data[ 2] + $fcefa3f8, 9);
Round2(C, D, A, B, Data[ 7] + $676f02d9, 14);
Round2(B, C, D, A, Data[12] + $8d2a4c8a, 20);

Round3(A, B, C, D, Data[ 5] + $fffa3942, 4);
Round3(D, A, B, C, Data[ 8] + $8771f681, 11);
Round3(C, D, A, B, Data[11] + $6d9d6122, 16);
Round3(B, C, D, A, Data[14] + $fde5380c, 23);
Round3(A, B, C, D, Data[ 1] + $a4beea44, 4);
Round3(D, A, B, C, Data[ 4] + $4bdecfa9, 11);
Round3(C, D, A, B, Data[ 7] + $f6bb4b60, 16);
Round3(B, C, D, A, Data[10] + $bebfbc70, 23);
Round3(A, B, C, D, Data[13] + $289b7ec6, 4);
Round3(D, A, B, C, Data[ 0] + $eaa127fa, 11);
Round3(C, D, A, B, Data[ 3] + $d4ef3085, 16);
Round3(B, C, D, A, Data[ 6] + $04881d05, 23);
Round3(A, B, C, D, Data[ 9] + $d9d4d039, 4);
Round3(D, A, B, C, Data[12] + $e6db99e5, 11);
Round3(C, D, A, B, Data[15] + $1fa27cf8, 16);
Round3(B, C, D, A, Data[ 2] + $c4ac5665, 23);

Round4(A, B, C, D, Data[ 0] + $f4292244, 6);
Round4(D, A, B, C, Data[ 7] + $432aff97, 10);
Round4(C, D, A, B, Data[14] + $ab9423a7, 15);
Round4(B, C, D, A, Data[ 5] + $fc93a039, 21);
Round4(A, B, C, D, Data[12] + $655b59c3, 6);
Round4(D, A, B, C, Data[ 3] + $8f0ccc92, 10);
Round4(C, D, A, B, Data[10] + $ffeff47d, 15);
Round4(B, C, D, A, Data[ 1] + $85845dd1, 21);
Round4(A, B, C, D, Data[ 8] + $6fa87e4f, 6);
Round4(D, A, B, C, Data[15] + $fe2ce6e0, 10);
Round4(C, D, A, B, Data[ 6] + $a3014314, 15);
Round4(B, C, D, A, Data[13] + $4e0811a1, 21);
Round4(A, B, C, D, Data[ 4] + $f7537e82, 6);
Round4(D, A, B, C, Data[11] + $bd3af235, 10);
Round4(C, D, A, B, Data[ 2] + $2ad7d2bb, 15);
Round4(B, C, D, A, Data[ 9] + $eb86d391, 21);

Inc(Buf[0], A);
Inc(Buf[1], B);
Inc(Buf[2], C);
Inc(Buf[3], D);
end;


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procedure MD5UpdateBuffer(
var MD5Context: TMD5Context;
Buffer: Pointer;
BufSize: Integer);
var
BufTmp : PMD5Buffer;
BufPtr : PChar;
Bytes : Word;
begin
New(BufTmp);
BufPtr := Buffer;
try
repeat
if BufSize > MaxBufSize then
Bytes := MaxBufSize
else
Bytes := BufSize;
Move(BufPtr^, BufTmp^, Bytes);
Inc(BufPtr, Bytes);
Dec(BufSize, Bytes);
if Bytes > 0 then
MD5Update(MD5Context, BufTmp^, Bytes);
until Bytes < MaxBufSize;
finally
Dispose(BufTmp);
end;
end;


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function GetMD5(Buffer: Pointer; BufSize: Integer): string;
var
I : Integer;
MD5Digest : TMD5Digest;
MD5Context : TMD5Context;
begin
for I := 0 to 15 do
Byte(MD5Digest[I]) := I + 1;
MD5Init(MD5Context);
MD5UpdateBuffer(MD5Context, Buffer, BufSize);
MD5Final(MD5Digest, MD5Context);
Result := '';
for I := 0 to 15 do
Result := Result + IntToHex(Byte(MD5Digest[I]), 2);
end;


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function StrMD5(Buffer : String): string;
begin
Result := GetMD5(@Buffer[1], Length(Buffer));
end;


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end.

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