Hi, I'm Evan Sixtin, I write for BTCManager.com and this will be my first Steemit article. I wanted to write a very basic guide for keeping cryptocurrencies safe without the extra cost of buying a Ledger or Trezor type hardware wallet.
Offline Storage and Offline Address Generator
So the first thing you want to do is download an offline cryptocurrency address generator. There are several options for this including https://walletgenerator.net/, or you can search Google for a specific cryptocurrency's offline address generator. Once you found that, do not use it. Yes, do not use it online. Download the webpage and save it to your computer.
Create a Linux (or other Operating System) Live Boot USB Drive
This is not hard. Just choose any Linux distro like Ubuntu, or another OS other than Linux that offers a live demo of their OS which can be put on a USB boot drive. Download the .iso file and be sure to validate it with the maker's PGP signature and the accompanying file containing SHA signature. Then use a Live USB creator application like Rufus (https://rufus.akeo.ie/) to put the .iso file on a bootable USB drive. Do not choose persistance. This means that you will not create any area on the USB disc that will save changes, settings, files after you shut down. You don't want to save anything.
Create and Save Public and Private Keys
Boot up the Live USB drive and make sure wifi, bluetooth, and any internet or wired or wireless connection is disabled and unplugged. Then copy over the address generating webpage files from another source. Unmount the source. Run the webpage and generate about 10 public and private keys, and save these to a simple text (.txt) file. Then create another text file and copy only the public keys to it.
Encrypt the Text File Containing the Private Keys
You can use PGP symmetric encryption to encrypt the file with a single password. Make sure it's a good strong password and that you will never, never forget it. Encrypt the text file containing the 10 public addresses and 10 private keys. You do not need to encrypt the text file containing only the public addresses. Then use the shred function (Linux) or a similar disc wiping deletion method to delete the unencrypted text file containing the private keys. Copy the encrypted text file and the unencrypted file containing only the public addresses to a clean freshly formatted USB drive. Remove the drive, and shut down the computer.
Lock the USB Drive in Self-Storage Unit or Bank Vault or Hide It Really Well
It's up to you what you want to do with the USB drive. But be sure to copy the public addresses before you store it away.
Break Your Holdings Up Into Different Accounts
Perhaps the most important step. Do not keep a large amount of any cryptocurrency in one address. Send it out and break it up into smaller amounts among the 10 addresses you created.
When You Need To Spend
Get the USB drive containing the private keys out, load up the bootable Live USB drive and be sure you are completely unconnected to any wired or wireless network. Decrypt the file and copy one private key only to a new text file. Delete securely the unencrypted text file with all your 10 private keys. And copy the one private key for one address over to a freshly formatted USB drive. Shut down. Enter the private key into whichever wallet you are using in order to spend from it. Spend the entire amount. This is important. If you do not need all the funds in that one address, then send the rest to a new fresh address that you made with the first steps outlined in this article. Once you use the private key to spend from the address, empty it, and don't use it again. And store away your USB drive again with your private keys.
So...I know this is a very basic guide and the methods described here are not fullproof. I take no responsibility if something goes wrong. I declare now that I am not liable, you are on your own. However, for most normal circumstances, this method should be ok. You can also add your own tweaks to make it even more secure. Feel free to comment with your experiences, advices, and/or corrections.