All geek questions in one place

Using a digital signature to provide a QR code

I was looking for something like “inverted asymmetric cryptography” and came across a great post that actually covers what I need.

I want every user of my application to have a public key that allows them to decrypt the message hidden in the QR code, which was encrypted with my private key. I want to make sure that my system cannot be tricked by a fake QR code covering mine. The accepted answer suggests using digital signature, so I googled a Java tutorial that shows how to use this feature.

There is a slight misunderstanding. I thought that using a digital signature would be a simple situation (let name it Situation A):

  • The message is encrypted with a private key.
  • User reads encrypted message
  • The user uses the public key to decrypt the message.

However, I understand that a digital signature works more like:

  • A digital signature is created using the private key and message.
  • The user needs the original message and the signature file.
  • The user uses a digital signature to verify that the message has not been modified and comes from me.

I'm here? If so, how can I put both of my messages and signature in a QR code? Things seemed pretty easy in the case Situation A, because I could just encode the encrypted message with Base64 and put the result in a QR code. However, it seems like I cannot do the same without using type tricks encode message, encode signature, put them in one file, encode it, put the result in the code. How can i do this?

, " QR-" :

, , QR-, Base-64, . , ; , , , .

, , .

+5
3

, , - - . , , DarkSquirrel42.

. , , .

  • , base64

  • ,

    base64(message)-base64(signature)

  • Base64() :

    base64(base64(message)-base64(signature))

  • QR-.

  • - base64, message signature ( 3.), , .
0

, , ...

- ... , ...

PGP, , ...

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

<your message here>

-----BEGIN PGP SIGNATURE-----  
Version: GnuPG v1.4.9 (GNU/Linux)  

<some base64 encoded data holding the signature>  
-----END PGP SIGNATURE-----

, pgp, , , - , ...

, , , , 2 ....

, base64, ,

0

, , , , .

0

Source: https://habr.com/ru/post/1569485/

More articles:


All Articles