Hilfe bei Umstellung Unit DEC5.1 zu DEC6.0

[Kas Ob.]

Hard bug to catch !, i can't reproduce this so will move to divide and conquer, for that we need to separate the decryption from MAC calculation.

Please try this, if you are in the mood to test deeper or you have time, this will show if the MAC is the failed point or not:

Code:

unit Tools.Crypt;

interface

uses
  System.SysUtils, DECUtil, DECHash, DECCipherBase, DECCiphers, DECHashBase,
  DECFormatBase, DECFormat, DECRandom, DECHashAuthentication;

const
  conKey = 'aYr14iaz8u)xO7Ok';

var
  CipherMode: TCipherMode = cmCBCx;
  HashClass: TDECHashClass = THash_SHA256;
  TextFormat: TDECFormatClass = TFormat_Base64;
  KDFIndex: Integer = 1;  // Iterations

type
  TToolsCrypt = class
  public
    class function Decrypt(const aHash: string; out NoAuthResult: string; aKey: string = ''): string;
    class function Encrypt(const aText: string; aKey: string = ''): string;
  end;

implementation

{ TToolsCrypt }

class function TToolsCrypt.Decrypt(const aHash: string; out NoAuthResult: string; aKey: string): string;
var
  Cipher: TCipher_Rijndael;
  Salt, Data, Check, Pass, Mac: TBytes;
  MacLength, SaltLen, DataLen: Integer;
begin
  if aKey = '' then
  begin
    aKey := conKey;
  end;

  Cipher := TCipher_Rijndael.Create;
  try
    MacLength := Cipher.Context.BlockSize;
    SaltLen := Cipher.InitVectorSize;

    Salt := ValidFormat(TextFormat).Decode(BytesOf(aHash));
    DataLen := Length(Salt) - MacLength - Cipher.Context.BufferSize;

    Data := Copy(Salt, MacLength, DataLen);
    Check := Copy(Salt, DataLen + SaltLen, Cipher.Context.BufferSize);

    SetLength(Salt, SaltLen);
    Pass := ValidAuthenticationHash(HashClass).KDFx(aKey[Low(aKey)], Length(aKey) * SizeOf(Char), Salt[Low(Salt)], Length(Salt), Cipher.Context.KeySize, KDFIndex);

    Cipher.Mode := CipherMode;
    Cipher.Init(Pass, nil);
    SetLength(Result, DataLen div SizeOf(Char));

    Cipher.Decode(Data[Low(Data)], Result[Low(Result)], DataLen);
    NoAuthResult := Result;

    Mac := BytesOf(Cipher.CalcMAC);
    if MacLength < Length(Check) then
      MacLength := Length(Check);

    if (MacLength <> Cipher.Context.BlockSize) or (not CompareMem(Check, Mac, MacLength)) then
    begin
      Result := '';
    end;

  finally
    Cipher.Free;
    ProtectBytes(Salt);
    ProtectBytes(Check);
    ProtectBytes(Data);
    ProtectBytes(Pass);
    ProtectBytes(Mac);
  end;
end;

class function TToolsCrypt.Encrypt(const aText: string; aKey: string): string;
var
  Cipher: TCipher_Rijndael;
  Salt, Pass, Data, Mac: TBytes;
begin
  if aKey = '' then
  begin
    aKey := conKey;
  end;

  Cipher := TCipher_Rijndael.Create;
  try
    Salt := RandomBytes(Cipher.InitVectorSize);
    Pass := ValidAuthenticationHash(HashClass).KDFx(aKey[Low(aKey)], Length(aKey) * SizeOf(Char), Salt[Low(Salt)], Length(Salt), Cipher.Context.KeySize, KDFIndex);
    Cipher.Mode := CipherMode;

    Cipher.Mode := cmCBCx;
    Cipher.Init(Pass, nil);

    SetLength(Data, Length(aText) * SizeOf(Char));
    Cipher.Encode(aText[Low(aText)], Data[Low(Data)], Length(Data));

    Mac := BytesOf(Cipher.CalcMAC);
    Result := StringOf(ValidFormat(TextFormat).Encode(Salt + Data + Mac));
  finally
    Cipher.Free;
    ProtectBytes(Salt);
    ProtectBytes(Pass);
    ProtectBytes(Data);
    ProtectBytes(Mac);
  end;
end;

end.

When the result is empty check and log the content of NoAuthResult, please if possible log it in plain text and in HEX formatted form.