Encryption question

[GaNdAlF89]

I want to create an encrypted string based on a personal key, how can I do?
I saw some example of encryption, but I don't found any based on personal key..

 

[Erel]

What do you mean with personal key? Do you mean private key? These are usually used for signatures not encryption.

 

[GaNdAlF89]

Yes, something like a signature, how can I do?

 

[Erel]

Do you want to encrypt the string? Signing a string will not encrypt it.

 

[GaNdAlF89]

In my app I want to release tickets, where I print a QRCode. Then, from another device running my app, I use this QRCode to recognize if ticket is valid (it was released by my app); to do this I want to include a string in QRCode, but I want "something" that can be recognized only by me. This is my question.

 

[agraham]

I would suggest that you include something unique on each ticket, like a serial number or a random set of characters, and also include a signature of that item signed with a private key. You, and anyone else, can then check with your public key that you signed the contents of that ticket and so it is valid. there is an example of something like this in Sub btnDsa_Click in the Encryption library demo.

 

[GaNdAlF89]

Yes, I thought to include the serial number of ticket, and add a string depending from it, but only I can verify this (if this string really depends from the serial number). Can you help me to do this with an example code? Thanks for all!

 

[agraham]

As I said above

there is an example of something like this in Sub btnDsa_Click in the Encryption library demo.