[fpc-pascal] HMAC_SHA1 and FPC

[David Butler]

congrats on re-inventing the wheel. all those string
allocations/de-allocations could make it slow.

On Sun, Mar 24, 2013 at 6:12 AM, silvioprog <silvioprog at gmail.com> wrote:

> Eureka!
>
> After spending all day working on it, I finally did it! The pseudo steps
> are here:
> http://en.wikipedia.org/wiki/Hash-based_message_authentication_code
>
> And, this is the final code (please improves it please):
>
> uses
>   SHA1;
>
> function SHA1Raw(const ABuffer; const ABufferLength: PtrUInt): string;
> var
>   I: Byte;
>   VBytes : TBytes;
>   VDigest: TSHA1Digest;
>   VContext: TSHA1Context;
> begin
>   Result := '';
>   SHA1Init(VContext);
>   SHA1Update(VContext, ABuffer, ABufferLength);
>   SHA1Final(VContext, VDigest);
>   SetLength(VBytes, 20);
>   Move(VDigest, VBytes[0], 20);
>   for I := 0 to 19 do
>     Result := Result + Char(VBytes[I]);
> end;
>
> function HMACSHA1(const AKey, AMessage: string): string;
> const
>   BLOCK_SIZE = 64;
> var
>   I: Byte;
>   VKey: string;
>   VLenght: PtrUInt;
>   VOPadStr, VIPadStr: string;
>   VOPad, VIPad: array[1..BLOCK_SIZE] of Byte;
> begin
>   VLenght := Length(AKey);
>   if VLenght > BLOCK_SIZE then
>   begin
>     SetLength(VKey, BLOCK_SIZE);
>     FillChar(Pointer(VKey)^, BLOCK_SIZE, #0);
>     VKey := SHA1Raw(Pointer(AKey)^, VLenght) + VKey;
>   end
>   else
>   begin
>     SetLength(VKey, BLOCK_SIZE - VLenght);
>     FillChar(Pointer(VKey)^, BLOCK_SIZE - VLenght, #0);
>     VKey := AKey + VKey;
>   end;
>   FillChar(VOPad, BLOCK_SIZE, $5c);
>   FillChar(VIPad, BLOCK_SIZE, $36);
>   for I := 1 to BLOCK_SIZE do
>   begin
>     VOPad[I] := VOPad[I] xor Byte(VKey[I]);
>     VIPad[I] := VIPad[I] xor Byte(VKey[I]);
>   end;
>   SetLength(VOPadStr, BLOCK_SIZE);
>   Move(VOPad, Pointer(VOPadStr)^, BLOCK_SIZE);
>   SetLength(VIPadStr, BLOCK_SIZE);
>   Move(VIPad, Pointer(VIPadStr)^, BLOCK_SIZE);
>   VIPadStr := VIPadStr + AMessage;
>   Result := SHA1Print(SHA1String(VOPadStr +
>     SHA1Raw(Pointer(VIPadStr)^, Length(VIPadStr))));
> end;
>
> Usage:
>
> WriteLn(HMACSHA1('key', 'The quick brown fox jumped over the lazy dog.')).
>
> Result: 0b7252985d63555b31db4755f37efe218c509711 (same result in PHP, JS
> and Phyton! ;) )
>
> So, can you add this code (I'll make HMACMD5 too) in FCL hashes?
> (>fpc\VER\source\packages\hash\src)
>
> Thank you very much buddies! :)
>
> --
> Silvio Clécio
> My public projects - github.com/silvioprog
>
> _______________________________________________
> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>
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