BytesToString not giving expected output

Question

The Indy function BytesToString is giving me funny results, i.e. not the one I am expecting.

Here is my code;

function String2Hex(S: String): String;
var I: Integer;
begin
  Result:= '';
  for I := 1 to length (S) do
    Result:= Result+IntToHex(ord(S[i]),2);
end;

function SHA1FromString(AString:AnsiString): TidBytes;
var
  SHA1: TIdHashSHA1;
begin
  SHA1 := TIdHashSHA1.Create;
  try
    //Result := SHA1.HashBytes(AString);
    Result := SHA1.HashString(AString, IndyTextEncoding_UTF8)
   // SHA1.HashStringAsHex(UTF8Encode(AString), IndyTextEncoding_UTF8);

  finally
    SHA1.Free;
  end;
end;

function bintoAscii(bin: array of byte): AnsiString;
var i: integer;
begin
  SetLength(Result, Length(bin));
  for i := 0 to Length(bin)-1 do
    Result[1+i] := AnsiChar(bin[i]);
end;

function HashSamsung(passcode: String; salt: Int64):AnsiString;
var
  salted_pass : AnsiString;
  g_digest:AnsiString;
  buf: TidBytes;
  I: Integer;
  step: tIDBytes;
  step2: AnsiString;
  salt_hex: AnsiString;
  a: AnsiString;
begin
  salt_Hex := LowerCase(IntToHex(salt, 2));


  salted_pass := passcode + salt_hex;
  buf := nil;
  step := nil;
  for I := 0 to 1023 do
  begin

    step2 := BytesToString(buf,IndyTextEncoding_UTF8) + IntToStr(i) + salted_pass;

    buf := SHA1FromString(step2);

    showmessage(String2Hex(BytesToString(buf,IndyTextEncoding_UTF8)));
    showmessage(String2Hex(bintoAscii(buf)));

  end;
  // showmessage(String2Hex(bintoAscii(buf) ));
 // Result := String2Hex(bintoAscii(buf));
 //Result := buf;

end;

The function is called as so;

HashSamsung('0000', 988796901418269782);

Now, when the code reaches the ShowMessage calls, the results are different on both message boxes. The output from the BytesToString message box is; FFFD2EFFFD0..... and the output from the bintoascii message box is; ab2ec50e0f.....

The second result is the one I am expecting. So my question is, why is the BytesToString function giving a different result to the bintoascii function?

score 2 · Answer 1 · edited May 23 '17 at 12:22

Based on the python script and example values in your other question, here is a Delphi translation that produces the same output:

function HashSamsung(const Passcode: String; Salt: Int64): String;
var
  salted_pass, step: String;
  buf: TIdBytes;
  I: Integer;
  SHA1: TIdHashSHA1;
begin
  salted_pass := Passcode + LowerCase(IntToHex(Salt, 2));
  SHA1 := TIdHashSHA1.Create;
  try
    for I := 0 to 1023 do
    begin
      step := BytesToStringRaw(buf) + IntToStr(i) + salted_pass;
      buf := SHA1.HashString(step, IndyTextEncoding_8Bit);
    end;
  finally
    SHA1.Free;
  end;
  Result := ToHex(buf);
end;

Alternatively:

function HashSamsung(const Passcode: String; Salt: Int64): String;
var
  salted_pass: TIdBytes;
  buf: TIdBytes;
  I: Integer;
  SHA1: TIdHashSHA1;
begin
  salted_pass := IndyTextEncoding_8Bit.GetBytes(Passcode + LowerCase(IntToHex(Salt, 2)));
  SHA1 := TIdHashSHA1.Create;
  try
    for I := 0 to 1023 do
    begin
      AppendString(buf, IntToStr(i));
      AppendBytes(buf, salted_pass);
      buf := SHA1.HashBytes(buf);
    end;
  finally
    SHA1.Free;
  end;
  Result := ToHex(buf);
end;

Either way, here is the output:

procedure Test;
begin
  ShowMessage(HashSamsung('1234', 988796901418269782));
end;

DC59AACF2AFCE72E737190323022FFB6E2831446

David Heffernan · Answer 2 · 2015-04-15T22:35:49.007

1

Your bintoAscii function interprets the bytes as if they are ANSI encoded.
You use of BytesToString treats the bytes as if they were UTF-8 encoded.

Since you've used different text encodings, you can expect different output.

I don't know what you are trying to achieve. However it seems that you are attempting to store binary data into string variables, which is invariably wrong.

edited Apr 15 '15 at 22:35

answered Apr 15 '15 at 22:24

David Heffernan

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So how do I make `BytesToString` use ANSI encoding? – Jake Evans Apr 15 '15 at 22:30
[`IndyTextEncoding_OSDefault`](http://stackoverflow.com/questions/25030477/encoding-in-indy-10-and-delphi) I think. It looks very much as though you are doing this wrongly though. You should not be putting binary data into strings. – David Heffernan Apr 15 '15 at 22:34
Unless you want to read the binary data for some reason - I have yet to meet or know of someone who can do so. – Jerry Dodge Apr 15 '15 at 23:27
@Jerry that's not the point. Binary data belongs in byte arrays. Strings hold text. – David Heffernan Apr 16 '15 at 06:04
@David Yes, that's my point too. You can't read binary, so why ever convert it to text? – Jerry Dodge Apr 16 '15 at 12:22

BytesToString not giving expected output

2 Answers2