AES-128 ECB decrypt example
lazarus / 38-Networking and Web Programming

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CC · 2021-01-29 01:27

Hi,

as the title says it.
I have looked around but I could not find anything truly useful.

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lainz · 2021-01-29 02:53

In other words Rijndael.

https://wiki.freepascal.org/DCPcrypt

Check that package, it has useful demos.

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trev · 2021-01-29 02:54

You didn't look very far... this post for example.

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CC · 2021-01-29 11:31

I have spent quite a few hours on this before asking and I did find
the exact links provided here. Just figured that copy-pasting an
example would be the least time consuming help. Faster then looking at
my code. But here it is anyway. I know the format  the result should
be, but it currently is gibberish.

The input length is 87.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
TForm1.AES128_ECB_Decrypt(AString, aKey: string): string;var  inData
 : TBytes;  outData : TBytes;  StreamSize: Int64;  KeySizeInBytes,
BlockSize: integer;  inStream,outStream: TStringStream;  
//inStreambegin  inStream:= TStringStream.Create(AString); 
StreamSize:=  inStream.Size;  outStream:= TStringStream.Create;   try 
   KeySizeInBytes:= 16;     BlockSize:= KeySizeInBytes;   
 SetLength(inData, BlockSize);     SetLength(outData, BlockSize);   
 //AES_Cipher := TDCP_rijndael.Create(nil); // already exists   
 AES_Cipher.Init(aKey , 128, nil );      While StreamSize > 0 do   
 begin       inStream.ReadBuffer(inData[0], BlockSize);     
 AES_Cipher.DecryptECB(inData[0], outData[0]);     
 outStream.WriteBuffer(outData[0], BlockSize);       Log(inData);    
 Log(outData);       Dec(StreamSize, BlockSize);       if StreamSize <
KeySizeInBytes then  // Last block less then key size       begin    
    BlockSize:= StreamSize;          SetLength(inData, BlockSize);   
     SetLength(outData, BlockSize);       end;     end;     result:=
outStream.DataString;   finally     inStream.Free;   
 outStream.Free;   end;end;                               
Result:
Quote??M??.?I???RM?4?(%?=?6????ro?Id??m
??)\??
NO[??5??.????܊??r>?w𷋊xլ?k

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CC · 2021-01-29 19:17

I still do not see what is wrong with the above code, but I got it
working with mORMot lib SynCrypto.TAESECB.
It is higher level solution, only few lines of code to use it. Base64
decoding may be necessary  first though.