[Gambas-user] Cipher doesn't read ciphered text

[Rolf-Werner Eilert]

Am 29.09.20 um 15:18 schrieb T Lee Davidson:
> On 9/29/20 7:17 AM, Rolf-Werner Eilert wrote:
>> I played around with Cipher, extending it by loading a small ASCII 
>> text file (2016 Bytes) with File.Load. The string is crypted and when 
>> I want it decrypted, Gambas says "Decryption failed".
>>
>> A short string like "hello world" is ok, it does even accept umlauts. 
>> So, where's the problem? Too long? Unfortunately, the documentation 
>> isn't complete and the error message doesn't say why.
>>
>> Regards
>> Rolf
> 
> Does decryption fail if you explicitly set a string variable to the 
> encrypted text instead of loading from a file?
> How was the ASCII text file created?
> 
> I ask because some text editors can be set to add a newline at the end 
> of a file if there is not one. Perhaps examine the text file with a hex 
> editor, or try something like:
> sEncryptedText = Trim(File.Load("encrypted.txt"))
> 
> If it's not that, can you provide an example project?
> 
> 

This is the code, it's from the example and slightly altered. I used a 
TextEdit to show the results, then saved the crypted text to investigate 
with a hex editor. (I use My.File here, as the original one contains a 
name.)

   t$ = File.Load("/klein/kartei/T18/My.File")
   't$ = "Hallo öäüß"
   sCipher = Cipher["AES-256-CBC"].EncryptSalted(t$, "secret")
   TextEdit1.Text = "Cipher text (base64): " & Base64$(sCipher) & Chr$(10)
   sData = Cipher["AES-256-CBC"].DecryptSalted(sCipher, "secret")
   TextEdit1.Text &= "Decrypted: " & sData & Chr$(10)

   File.Save("~/Gambas3/testEditor/test.cipher", sCipher)



It fails in the line "sDate = Cipher...", so it cannot decrypt the 
string it crypted before. I tried another, even longer file, and it ran 
flawlessly. So I cannot make out what caused the error.

Both files are made up the same way, they contain a CR+LF pair after 
each line to make the files compatible to an older Windows program that 
reads them. But that doesn't seem to be the reason.

Regards
Rolf