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How we store your Stellar secret key

September 14, 2019

Every LockerX user has available a Stellar wallet they can use to create smart contracts.

To access your wallet (identified by its public key), you need to use the corresponding secret key that is known only to you. Usually, the secret key is safely stored by the wallet software you use. Knowing an account’s secret key gives complete control over it, it is then clear that the secret key should never be shared with anyone and should be kept as safe as possible.


Every time you create a smart contract using LockerX, we will create a new Stellar account on the network for the smart contract. This means that we have to manage hundreds or thousands of secret keys, and make sure they are safe!


The basics of keeping keys secure are:

  • Never transmit the keys over the network. Ideally, the unencrypted keys should never leave the process memory.
  • Encrypt the keys before storing them in the database.
  • Encrypt the database data at rest.
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Stellar Assets Explained

May 1, 2019

When Bitcoin was presented in 2008 it showed that it was possible to have a decentralized and trustless currency. In the following decade we witnessed the rise of many different cryptocurrencies, each one with a different goal and philosophy.


While cryptocurrencies can differ greatly from each other, they can be divided into four groups:

  • Cryptocurrencies/Payment Tokens: these tokens have no inherent value and are used as a medium of exchange on the network. Payment tokens are usually used to pay for network fees. Stellar Lumens are an example of cryptocurrency.
  • Stablecoins: these are tokens that are backed 1:1 by another asset, usually a fiat currency held in a deposit account. Users trust the stablecoin issuer to exchange back the token for fiat currency. Coinbase USDC is an example of stablecoin, you can always redeem 1 USDC for 1$.
  • Utility Tokens: these tokens are used to pay for a service. The Basic Attention Token (BAT) is a utility token used to obtain advertising-related services and it’s exchanged between users, publishers and advertisers.
  • Security Tokens: these tokens represent ownership of an asset, for example a company or a property. This type of tokens are less common because securities are regulated in most countries and early stage companies (the most likely candidates for Initial Coin Offerings) don’t have the resources to comply with all the regulations.

Originally new tokens were created by forking an existing project and changing the protocol to meet the requirements. Ethereum revolutionized this process by letting users program smart contracts that behaved like currencies, later it was formalized in the ERC20 standard.

The Stellar Network supports non-native assets directly, letting users issue and exchange their different assets. In this blog post we begin by giving an high-level overview of Stellar Assets, compare them with ERC20 tokens, and finally delve into the technical details.

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An Introduction to Stellar Smart Contract Development

April 1, 2019

With the term smart contracts we usually define computer programs that are executed by a distributed computer. This is the case, for example, of Ethereum smart contracts, built using the Solidity programming language. While targeting a Turing-complete virtual machine empowers programmers to build exceptionally complex contracts, it also increases the possibility of bugs that result in the loss of millions of dollars.

Stellar takes a different approach to smart contracts. Contracts are built by composing transactions together and taking advantage of the following features:

  • Multisignature, Thresholds, and Key Weights We can specify what signature are required to change the state of an account
  • Batching Either all operations in a transaction succeed or none of them does
  • Sequence Transactions are processed only if their sequence number is increasing
  • Time Bounds Limit the time frame within which transactions can be accepted by the Stellar Network

While this limits what it’s possible to build on top of Stellar smart contracts, it also results in contracts that are more safe from unexpected bugs. As we will see later in this post, it is possible to model smart contracts as state machines, resulting in contracts that are easier to verify and test.

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First look at the new BumpSequence Operation

March 1, 2019

Stellar Protocol version 10 is going to be released soon. This release brings several changes to the distributed exchange, and introduces a new BumpSequenceOperation.

Bump sequence has been in the work since last October and it was added to simplify writing complex Stellar smart contract workflows. The operation allows to bump forward the sequence number of the source account of the operation. If the sequence number specified in the bump sequence operation is less than the account current sequence number, then the account sequence number will be unaffected. In practice, it means Stellar now includes a no-op operation.

Let’s now look at two use cases for the bump sequence operation.

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