Tag : android

Claim US$20 for free from Byteball

Byteball is offering US$20 to anyone who installs the wallet and verifies his identity. The verification process is privately done by Jumio through the Byteball wallet; your information will not be public. Only a hash is published to prove you completed the process.

This process has a cost of US$8 but, because of its referral program, I can cover this for you. Just follow these steps:

  • Enter a name and make sure you enable the option “Single address wallet”

  • Go to “Chat”, select “Bot Store” and find “Real name attestation bot”. Select it and add it

  • Open that chat. If no message is shown, write anything to start, for example “?”. Read the instructions. When asked, enter your own address by touching the¬† icon

  • When asked if you want to store your information private or public, it’s OK to select private
  • Now, the bot will ask you to pay US$8 for the attestation fee. I can cover this for you if:
    • You’re using your passport to verify, not your ID nor your driving license.
    • You have a bitcointalk.org account
    • Your account is Senior, Hero or Legendary with neutral or green trust; or your account is below Senior with green trust by default
    • You commit to use the US$8 to pay for attestation. Take a screenshot (how?) of the process once you’re done to prove this, even if it fails
    • If you don’t use these US$8 to complete this process, you may get negative trust. If you try and the process fails for any reason, of course you won’t get negative trust. But do PM me the screenshot
  • Copy your own address (touch-and-hodl the address you just sent) and PM it to me: https://bitcointalk.org/index.php?action=pm;sa=send;u=169515

  • I’ll send the required amount to your address. Wait until you receive it and it confirms. Go back to the chat and make the payment. For this, touch the “Payment request” link and confirm on the next screen

  • You will receive a unique link to start the verification process. Touch the link to start the process

  • You will then be asked to take a picture of your passport and a selfie. Make sure both pictures are in focus and fully readable.
    Note the site supports a passport, ID or driving license. However, using a passport is strongly recommended as the process can fail if using an ID or license driving. Most probably this happens because formats of IDs and driving licenses change a lot from country to country, unlike passports.
  • Wait a few minutes and you’ll get your $US20 which you can keep or trade

  • Done!

Categories: Crypto-currencies, Giveaways, Tutorials

Deck Wallet: Store your bitcoins in a deck of cards

Bitcoin Deck Wallet
Store your bitcoins in a deck of cards
The most secure way to store coins offline.

See more screenshots here

I’ve read on several places the idea to use real-world entropy such as dice or cards to generate a seed to create bitcoin addresses.

Basing on that idea, I have create a simple Android app that allows users to generate up to 52 bitcoin addresses from a deck of cards.

You can get it here from Google Play:

or https://github.com/ecuamobi/deck-wallet/blob/master/market/DeckWallet_1.0.apk?raw=true
It requires a device running Android 4.0+ with touchscreen.


  • Easily enter the order of the cards by using spinners.
  • Supports an optional password.
  • Checks for repeated or missing cards, as well as miss-entered passwords.
  • Allows the user to re-enter everything to double-check the generated wallet. This is to prevent sending coins to the void.
  • Shows QR codes for the generated addresses and private keys.
  • Allows individual sharing of an address or key, as well as bulk sharing of all generated addresses.

About security

  • Completely offline. The application does not requires permission to access the Internet, store files, or any other.
  • Open source. The code is available here: https://github.com/ecuamobi/deck-wallet/
  • You don’t need to enter the order of the cards using the keyboard, therefore it’s not vulnerable to malicious keyboards.
  • Checks for repeated or missing cards.
  • Allows the user to re-enter everything to double-check the generated wallet.
  • 2FA: Option to enter a password (or more than one to create secondary wallets) besides the deck itself.
  • Allows the generation on an extra wallet using a secondary password, thus protecting the main one against a physical attack (disclose the secondary password instead of the main one).
  • Obscurity: An attacker won’t know there are bitcoins in that deck, even if they find it.


  • Install Deck Wallet on a non-rooted Android device.
    Important: Make sure to download only from either
    https://play.google.com/store/apps/details?id=com.ecuamobi.deckwallet or
    and double check it does not require any permissions.
  • Riffle shuffle a deck of cards 7 times or more.
  • Select the number of cards to use. 52 is recommended.
  • Enter every card on the app (it takes me about 4 or 5 minutes to do so).
  • Optionally enter a password you won’t forget (it’s not possible to recover it!).
  • Touch “Go!” to generate up to 52 bitcoin addresses. It will generate as many addresses as the number of entered cards.
  • Optionally, copy the order of the cards into another deck, as backup.
  • Double-check your deck wallet: Touch the ‘Check’ icon and re-enter the same password and card order.
  • After checking it, send some bitcoins to your deck wallet and store your deck of cards in a safe place.

How it works

  • The entered cards are converted to 2-char strings and concatenated. For example 3 of hearths is represented as 3H. 10, Jack, Queen and King are represented as T, J, Q and K respectively.
  • If a password is entered, it is pre-pended to the resulting string.
    Example seed: myPasswordAH4CTS9D…KHQS
  • The first address is calculated as a brain address, using SHA256 from the full generated seed. The result is the same as manually entering the full string into http://bitaddress.org or other similar tool.
  • The second address is calculated from the seed except the first card is moved to the end (Example: myPassword4CTS9D…KHQSAH)
  • The third address is calculated from the seed except the first 2 cards are moved to the end (Example: myPasswordTS9D…KHQSAH4C) and so on.
  • To check the generated wallet, the double SHA256 of the full seed is temporarily stored on RAM.
  • Nothing is stored permanently and nothing is sent or received through Internet (the app doesn’t have permission to do that).


If you find this app useful, please consider donating:
bitcoin: 1LACUzhZi3JnfPsmvkDLMfgKE7GU6RFPdQ

DeckWallet is open source released under the MIT license.

It is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement.

Originally announced (by myself) here.

Categories: Android, Crypto-currencies