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b.lock - The blockchain-powered password manager

Using encryption and blockchain technology, b.lock is a Chrome extension that helps you manage your passwords in a secure and trustless way such that only you have access to them.

alt text

Link to Chrome extension

Note: we have changed our encryption scheme to a more secure one, which is explained in Encryption and Decryption sections below


  • You can save the login credentials for different websites to b.lock. The saved credentials will be auto-filled when you visit the websites subsequently.
  • You can also save "Secret notes" such as bank PIN numbers, metamask seed words,...
  • b.lock acts as a Nebulas wallet as well. You can use it to keep NAS or send NAS to other accounts.

How to use:

  • Step 1: Download the chrome extension from here
  • Step 2: Following the extension’s instructions, create your “keystore” (which is like your master key) and back it up. You can also import your existing Nebulas keystore.
  • Step 3: Go to this link and get your free Nebulas coins (which is needed to run b.lock. Don’t worry, $0.0001 worth of the coin is enough to use b.lock for your lifetime. Hence, we are giving it free to you)
  • Step 4: Done, you can start using b.lock to save your passwords/secret notes

How it works

  • b.lock uses the Nebulas blockchain and each user account is linked to a Nebulas account.
  • b.lock uses your Nebulas private key (in other words, the master key) to encrypt your passwords and secret notes, using the AES-256 encryption algorithm.
  • b.lock saves the encrypted passwords/secret notes on the Nebulas blockchain.
  • Hence, your passwords will be accessible to you anytime and anywhere, as long as you have your private key
  • No one but you can decrypt the encrypted passwords. Thus, you are truly in control of your passwords.

For each password entry, a domain, login and password are encrypted and saved on the Nebulas blockchain. The encryption is as follow:

  • Two keys are generated from user's Nebulas private key: encryptionKey and counterGeneratingKey
encryptionKey = sha256(sha256(nebulas_private_key))
counterGeneratingKey = sha256(sha256(nebulas_private_key) + 'b.lock is awesome ' + network)

network is either 'mainnet' or 'testnet', depending on which Nebulas network is being used by the user.

  • "<domain>:<login>" is encrypted using CTR mode of the AES256 algorithm:
    • A random and unique nonce1 in the range from 0 to 1e16 is generated. This means that a random number is generated until it has not been used by the user before.
    • "<domain>:<login>" is encrypted with encryptionKey as the key and counterGeneratingKey % nonce1 as the Counter, to produce encryptedDomainAndLogin
  • Similarly, password is also encrypted using the CTR mode of the AES256 algorithm, with another random and unique nonce2, to produce encryptedPassword
  • An entry of ("<encryptedDomainAndLogin>:::<nonce1>", "<encryptedPassword>:::<nonce2>") is saved on the Nebulas blockchain
  • encryptedDomainAndLogin is simply decrypted using the encryptionKey as key and counterGeneratingKey % nonce1 as the Counter.
  • encryptedPassword is decrypted in a similar way.

Why blockchain?

  • Password managers are essential these days, when we have to manage lots of different passwords (which shouldn't be reused)
  • There are lots of potential problems with the existing centralized password managers:
    • Single point of failure: if the server/database goes down, there goes your passwords
    • Trust issue: can you really trust that these closed-source softwares will not just read your passwords?
  • b.lock solves all of these problems:
    • The passwords are stored on the decentralized database that is the Nebulas blockchain, hence it will not go down easily
    • The passwords are encrypted by your private key which belongs to only you. You are the only one who can see your saved passwords.

Contract address

Our deployed contract on the mainnet Nebulas can be found here.


  • BTC: 38emsJ9aCHmxqbFSN9rrpeeDpgEBxjD5kx
  • ETH: 0x033684fE1BcC2a6A86a4a1E44766CBF511FB8001
  • NAS: n1FymtHsTxTLrg1FpUTLEVrJFYKCjTkXoRa
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