[fpc-pascal] Re: encryption and decryption

[leledumbo]

> How to use TBlowFishEnCryptStream? Is there any example for mortals?

No but I guess the doc is clear enough.

To encrypt:
1. Create TBlowFishEnCryptStream instance supplying a key and the stream to
write encrypted data to
2. Write the data using its Write method
3. Flush or Free (Free implies Flush) to ensure all data are written

To decrypt:
1. Create TBlowFishDeCryptStream instance supplying a key and the stream
containing previously encrypted data. If you want to use directly previous
stream, ensure to Seek it to the first data. To be safe, create a new stream
instead and put the data from previous stream.
2. Read the data using its Read method (you should now the data length, for
some stream Size property can be used)

An example:

{$mode objfpc}{$H+}

uses classes,blowfish;

var
  en: TBlowFishEncryptStream;
  de: TBlowFishDeCryptStream;
  s1,s2: TStringStream;
  key,value,temp: String;
begin
  key := 'testkey';
  value := 'this is a string';

  s1 := TStringStream.Create('');
  en := TBlowFishEncryptStream.Create(key,s1);
    en.Write(value[1],Length(value));
  en.Free;

  WriteLn('encrypted: ' + s1.DataString);

  s2 := TStringStream.Create(s1.DataString);
  s1.Free;

  de := TBlowFishDeCryptStream.Create(key,s2);

  SetLength(temp,s2.Size);
  de.Read(temp[1],s2.Size);
  WriteLn('decrypted: ' + temp);
  de.Free;

  s2.Free;
end.


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