RSA.Verify fails in TMS Crypto 5.0.9.7

VCL TMS Cryptography Pack
1

Hi,

I'd like to report a bug in the TRSAEncSign component.
You can reproduce it with your own CryptoDemo:

image
image799×635 42.8 KB

The Verify button triggers the "Invalid Operation : -316" error.
Any idea to fix?

Thank you.

2

Hi, there seem to be a padding or conversion issue with this mode (PKCS 1.5 is fine). I need to investigate and will get back to you.

3

OK, here is the issue and the fix.

In a recent cleanup, I forgot a couple of things and a value is not copied in RSA PSS verification.

If you open up RSACore.pas, then look for PSSDepadding, you'll find this, circa line 1815:

  if messageLength > MAXINTBASE8 - 1 then begin
  	for I := 0 to messageLength - 1 do
  		messageInv[I] := PSSmessage[I]; // THIS NEVER HAPPENS, then the computed hash is incorrect
  end;

Then you have 2 options:

  • change the '>' sign into a '<' sign and you are done
  • delete these lines, delete 'messageInv' in the 'var' section and replace it by 'PSSmessage' in the rest of the function (where the compiler complains!)

I forgot do to the latter in the cleanup, my mistake.

You should then be fine with RSA PSS. RSA PKCS looks good.

1 Like
4

Yes, this fixed the issue. Thank you!

BTW another suggestion: please add HashStream in addition to HashFile to the different SHAx components. I added one myself, but it would be a great addition to the base component.

5

Perfect. The fix has been uploaded and will be issued in version 5.0.9.9, either today or tomorrow.

Feel free to send some code and/or suggestions for improvements.

6

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