How Secure is a Text Encryption Program Created with Visual Basic?

[niko421]

I taught myself to program a bit in Visual Basic. A while ago I made a text encryption program using my own methods and I was wondering how secure it would be.

It uses a random number between 10-99 in the encryption process. The number is appended to the beginning of the message.

For example:

'A' can encrypt to: '33k' '34k' '83p' '11i' etc..
'B' can encrypt to: '44m' '97r' '59n' '70p' etc..
'AAA' can encrypt to: '86j6V' '81j@V' '58g2M' etc..
'Hello' can encrypt to: '60id{kŠ' '48gTuK€' '19dRlGq'

How secure would encryption like this be? Every one of the examples decrypt properly to the original message using the program.

I'm just curious, any feedback from anyone who knows about this kind of thing would be awesome. Also, if its easy to crack, try to decipher the following coded message:

'69]ý†¨;³Gʘ§«*ÄBÅuÈb`êùí1¿Ëóó8ÒB{I®\Ÿc‰ ‚r!}]‡O©;°"·‚´´êÍÞãѤ²ÿ¬¼‰‰,i3[;G;^Ûbb}î„áB{¸¤¬y]‚'

 

[Coin]

Realistically... very unlikely to be secure at all. I couldn't crack it but there are various methods by which someone actually skilled in cryptanalysis just about certainly could, assuming that they had any meaningful amount of encrypted text to use as examples.

Crypto these days is considered to be secure basically only if even if you know exactly how the encryption method works, you can't recover the original message without either possessing a secret decryption key or solving an "intractable" computational problem. Your thing sounds like it's closer to an example of "security through obscurity", something which is secure only because nobody knows the secret method you used in your VB program. But there's a lot of research into ways of uncovering such methods by looking at ciphertext only...