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Programming => Networking and Web Programming => Topic started by: torbente on June 01, 2018, 08:08:03 pm

Title: [SOLVED] GEt a keyed SHA256 hash from string
Post by: torbente on June 01, 2018, 08:08:03 pm
Sometime ago, getmem gracefully help me a lot in this topic:
https://forum.lazarus.freepascal.org/index.php/topic,39821.msg274338.html#msg274338 (https://forum.lazarus.freepascal.org/index.php/topic,39821.msg274338.html#msg274338)

Now, i need the same, but using SHA256, so this is what im doing: (using dcpcrypt2)

Code: Pascal  [Select][+][-]
  1. function GetSignature(const AText, AKey: String): String;
  2. var
  3.   SHA256: TDCP_sha256;
  4.   AB: array[0..31] of byte;
  5.   I: Integer;
  6. begin
  7.   Result := '';
  8.   SHA256 := TDCP_sha256.Create(nil);
  9.   try
  10.     SHA256.Init;
  11.     SHA256.UpdateStr(AText + AKey);
  12.     SHA256.Final(AB);
  13.     for I := 0 to 31 do
  14.       Result := Result + IntToHex(AB[i], 2);
  15.   finally
  16.     SHA256.Free;
  17.   end;
  18. end;

But im receiving the "Signature for this request is not valid." message ALWAYS.

I used this page to test my code:
https://www.freeformatter.com/hmac-generator.html (https://www.freeformatter.com/hmac-generator.html)

And im getting different hashes. Any idea?
Title: Re: GEt a keyed SHA256 hash from string
Post by: Gammatester on June 01, 2018, 08:49:59 pm
You are not using a valid HMAC construction: HMAC is not HASH(Text+Key).

Actually it is HMAC(key,text) = hash((const1 xor key) || hash((const2 xor key) || text)) , see http://www.wolfgang-ehrhardt.de/hash_intro.html.
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 01, 2018, 08:59:57 pm
If you want to calculate hmac, you can use HashLib4Pascal
https://github.com/Xor-el/HashLib4Pascal
Title: Re: GEt a keyed SHA256 hash from string
Post by: Gammatester on June 01, 2018, 10:08:06 pm
Here is a complete test program for HMAC compiled with http://www.wolfgang-ehrhardt.de/crc_hash_2018-01-01.zip
Code: Pascal  [Select][+][-]
  1. uses
  2.   hash,hmac,hmacsha2,mem_util;
  3. const
  4.   akey = 'Key';
  5. const
  6.   atext: ansistring = 'Message';
  7. var
  8.   ctx: THMAC_Context;
  9.   mac: TSHA256Digest;
  10. begin
  11.   hmac_SHA256_inits(ctx, akey);
  12.   hmac_SHA256_updateXL(ctx, @atext[1], length(atext));
  13.   hmac_SHA256_final(ctx,mac);
  14.   writeln(HexStr(@mac, sizeof(mac)));
  15. end.
Code: [Select]
D:\Work\CRC_HASH>D:\FPC304\bin\i386-win32\fpc.exe -b THMACSHA.PAS
Free Pascal Compiler version 3.0.4 [2017/10/06] for i386
Copyright (c) 1993-2017 by Florian Klaempfl and others
Target OS: Win32 for i386
Compiling THMACSHA.PAS
Linking THMACSHA.exe
14 lines compiled, 0.1 sec, 30848 bytes code, 1764 bytes data

D:\Work\CRC_HASH>THMACSHA.exe
507285548137b5424eb5572c46496631b7ade8e88ac323c529fa142def26ffa1
and verified with your online-calculator.
Title: Re: GEt a keyed SHA256 hash from string
Post by: torbente on June 01, 2018, 11:54:10 pm
I used it and worked

Code: Pascal  [Select][+][-]
  1. function getsha256signature(StringToSign , mykey:string):string;
  2. var
  3.   LHMAC: IHMAC;
  4. begin
  5. LHMAC := THashFactory.THMAC.CreateHMAC(THashFactory.TCrypto.CreateSHA2_256);
  6. LHMAC.Key := TConverters.ConvertStringToBytes(MyKey, TEncoding.UTF8);
  7. getsha256signature := LHMAC.ComputeString(StringToSign, TEncoding.UTF8).ToString();
  8. end;


 but my app start crashing, probably due to this previous function i had:

Code: Pascal  [Select][+][-]
  1. function GetTimestamp():string;
  2. Begin
  3. GetTimestamp := inttostr(Trunc((Now - EncodeDate(1970, 1 ,1)) * 24 * 60 * 60));
  4. end;

ANy idea if this can be done with dcpcrypt?

Quote from: Xor-el on June 01, 2018, 08:59:57 pm
If you want to calculate hmac, you can use HashLib4Pascal
https://github.com/Xor-el/HashLib4Pascal

@Gammatester i will try your code. Thanks!!
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 02, 2018, 12:57:52 am
Quote from: torbente on June 01, 2018, 11:54:10 pm
I used it and worked

Code: Pascal  [Select][+][-]
  1. function getsha256signature(StringToSign , mykey:string):string;
  2. var
  3.   LHMAC: IHMAC;
  4. begin
  5. LHMAC := THashFactory.THMAC.CreateHMAC(THashFactory.TCrypto.CreateSHA2_256);
  6. LHMAC.Key := TConverters.ConvertStringToBytes(MyKey, TEncoding.UTF8);
  7. getsha256signature := LHMAC.ComputeString(StringToSign, TEncoding.UTF8).ToString();
  8. end;


 but my app start crashing, probably due to this previous function i had:

Code: Pascal  [Select][+][-]
  1. function GetTimestamp():string;
  2. Begin
  3. GetTimestamp := inttostr(Trunc((Now - EncodeDate(1970, 1 ,1)) * 24 * 60 * 60));
  4. end;

ANy idea if this can be done with dcpcrypt?

Quote from: Xor-el on June 01, 2018, 08:59:57 pm
If you want to calculate hmac, you can use HashLib4Pascal
https://github.com/Xor-el/HashLib4Pascal

@Gammatester i will try your code. Thanks!!

don't know why your code is crashing but HashLib4Pascal is obviously not the cause.
can you upload your code so we can check the cause of the crash?
Title: Re: GEt a keyed SHA256 hash from string
Post by: torbente on June 02, 2018, 07:50:02 am
Code: Pascal  [Select][+][-]
  1. don't know why your code is crashing but HashLib4Pascal is obviously not the cause.
  2. can you upload your code so we can check the cause of the crash?
I think HashLib4Pascal is obviously the cause; i removed it from my project and i had no more troubles since then. IF your are the library developer, check why it crashes with my custom timestamp function (if i remove GetTimestamp function, then getsha256signature works and the app do not crash)
Anyway, im cleaning my code to see if something else could be wrong.
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 02, 2018, 11:56:41 am
Quote from: torbente on June 02, 2018, 07:50:02 am
Code: Pascal  [Select][+][-]
  1. don't know why your code is crashing but HashLib4Pascal is obviously not the cause.
  2. can you upload your code so we can check the cause of the crash?
I think HashLib4Pascal is obviously the cause; i removed it from my project and i had no more troubles since then. IF your are the library developer, check why it crashes with my custom timestamp function (if i remove GetTimestamp function, then getsha256signature works and the app do not crash)
Anyway, im cleaning my code to see if something else could be wrong.
Yes I am the library developer.
I suggest you upload a small reproducible project where it crashes so we can help you out.
Title: Re: GEt a keyed SHA256 hash from string
Post by: torbente on June 02, 2018, 12:54:40 pm
I could send you the entire project by private. So you coudl check if it is something with your library.
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 02, 2018, 01:02:33 pm
Quote from: torbente on June 02, 2018, 12:54:40 pm
I could send you the entire project by private. So you coudl check if it is something with your library.
Please Go ahead.
Title: Re: GEt a keyed SHA256 hash from string
Post by: guest48180 on June 08, 2018, 07:28:55 am
It'd be nice to know how this turned out.
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 08, 2018, 10:28:03 am
Quote from: Landslyde on June 08, 2018, 07:28:55 am
It'd be nice to know how this turned out.

So after some investigations, it was discovered that it was a bug in his own code when parsing floating points.
It was not related to HashLib4Pascal or DCPCrypt for that matter.
The bug was not even related to his custom timestamp function.
Title: Re: GEt a keyed SHA256 hash from string
Post by: torbente on June 20, 2018, 03:08:24 am
Yes, it was a lack of error handlers in my code. I implemented all the necessary handlers and i had no more errors. Thanks  Xor-el for your time  :)
Title: Re: GEt a keyed SHA256 hash from string
Post by: Xor-el on June 20, 2018, 09:07:33 am
Quote from: torbente on June 20, 2018, 03:08:24 am
Yes, it was a lack of error handlers in my code. I implemented all the necessary handlers and i had no more errors. Thanks  Xor-el for your time  :)

You are welcome, glad you finally fixed it.
Title: Re: [SOLVED] GEt a keyed SHA256 hash from string
Post by: william22 on October 13, 2018, 03:40:43 pm
Dear Torbente,

If I'm right you wrote this for the KrakenAPI.
I'm working on a same project, but am stuck.
Could you share your code-project with me please?
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