Why is encrypted string(_StringEncrypt) almost same for every string with same PW?

[Aktonius]

I wish i can use one password to encrypt several strings but the problem is they end up almost all the same like if i encrypt

new york with password cities it will be something like 9881, washington encrypted with same pw will be something like 9882, Phoenix will be 9883 etc...

Is this really reliable way to encrypt things when people can just change one number in encrypted string and therefore get your data even if you dont want them to?

How can i encrypt strings with same password but make it that they are pretty much different so people can not guess like cities encrypted would instead be

Washington - 98CD

New York - 81X9

etc...

I tried to use deeper encrypt level but funny enough sometimes only 2 digits will change in that case no matter how deep your encrypt lvl is.

Maybe i am just paranoid but i i wish encryption would be different for each thing you encrypt while using same pw

Since i am using this for licensing algorythm i am working on you can see how this could cause problems like if user of program could just accidently hit another key and he would get completely different license!

Melba and others who perhaps know ways around this?

Edited December 3, 2011 by Aktonius

[Melba23]

Aktonius,

Simple answer - do not use _StringEncrypt!

Try _Crypt_EncryptData - a lot better:

#include <crypt.au3>

Global $aCities[3] = ["New York", "Washington", "Phoenix"]

_Crypt_Startup()

$hKey = _Crypt_DeriveKey("SomePassword", $CALG_RC4)

For $i = 0 To 2
    ; Encrypt the name
    $bEncrypted = _Crypt_EncryptData($aCities[$i], $hKey, $CALG_USERKEY)
    ; And then decrypt it
    $bDecrypted = _Crypt_DecryptData($bEncrypted, $hKey, $CALG_USERKEY)
    ; And display the 2 results
    ConsoleWrite($bEncrypted & " - " & BinaryToString($bDecrypted) & @CRLF)

Next

_Crypt_DestroyKey($hKey)
_Crypt_Shutdown()

All clear?

M23

Edit: Typnig!

Edited December 3, 2011 by Melba23

[Aktonius]

Thanks Melba, Works great and i like this better!

edit: There are still some typos though (Crypt_Startup, _For) in case you wanna edit

Edited December 3, 2011 by Aktonius

[Melba23]

Aktonius,

It should have read _Crypt_Startup() and it is an optional initialisation of the Crypt UDF library - I suggest you put it back in!

M23

Edit: I see you worked it out - and I have fixed the typos (stupid copy/paste error). I really do not like this new post editor at all!

Edited December 3, 2011 by Melba23

[Aktonius]

Yep, i see now after checking the au3 help file, all good.