I don’t know how other paper wallet generators on other blockchains work, but I can explain how my tool is working.
Blockchains use public / private key cryptography to secure funds and sign transactions. And this is exactly how my generator works as well. When you create a new paper wallet, the generator first creates a private key and then the public address/receiving address for that particular private key.
This is what you see on my paper wallets. The address on the left is your public address, used to receive funds. The one in the middle is your private key.
If someone sends funds to the address shown on the left, the transaction will be stored on the blockchain. You can always check the balance of an address with a block explorer. Everything is on chain.
To spend the funds, you need the private key. As soon as you import the private key to a wallet, you are able to sign transactions for the corresponding address and you can spend the funds.
This is how my paper wallet generator works.
“…to unlock this wallet, please install the Android…” --> This is just the easiest way to import the private key into a wallet, you can just scan the QR code. But you can also use any other NEM wallet and import the RAW private key. RAW private key and mobile import format private key are the same, just represented in a different way - and the mobile import format key contains some more information as well. But both are the same, just written in a different format.
Paper wallets from my generator have no expiry date. At least as long as NEM does not change the address creation algorithm. (this is highly unlikely)
Imo paper wallets are the safest way to store funds - IF you do it right:
- Keep your private key safe!!! A person having access to your private key can spend the funds!
Your keys - your money - it’s that simple.
- Only use paper wallet generators you trust, or better: Check the source code!
- Never use a generator that is not open source
- Never use a generator that creates lazy private keys (it is very important to have a secure random key)
- Never use online generators on the internet! Only use offline generators running on YOUR computer while the computer is disconnected from the network!
I hope I was able to clarify some things for you.
Have a good day!