Blockchain and Trust Infrastructure Engineer · path guide

Blockchain and Trust Infrastructure Engineer: path guide

Read this before you start. It explains what the role is, what you'll be able to do at the end, which core lessons you need, how to set up your tools, what it may cost and how long it really takes.

The role

A blockchain and trust infrastructure engineer builds systems where several people or organisations who don't fully trust each other can share a record, and check it, without one of them being in charge of it. They work with hashes, keys and signatures, with the rules a shared ledger uses to agree, and with smart contracts: small programs that hold money or records and can't be quietly changed once they're running. A large part of the job is saying no: deciding when an ordinary database with signed records does the job better. When a ledger is the right tool, they write contracts that are tested against attacks, set up approvals so no single key can move money, and build apps that read from and write to the network safely. Mistakes in this work are often public and hard to undo, so success is measured by what holds up under attack and under review, not by how quickly something was shipped.

Everyday applications

• A savings group's shared fund where members can see every deposit and withdrawal, and nobody can take more than their own balance.
• A trust's account that moves money only after three of its five trustees approve, so one lost or stolen key isn't enough.
• A certificate an institute signs, which an employer can check without phoning the institute.
• A record shared by several companies in a supply chain, where each change is signed by the company that made it.
• A review that shows a group they don't need a blockchain at all, and that a signed, append-only database costs far less.

What you'll be able to do

By the end of the path you will be able to:

1. PO1 Use hashes as fingerprints for data, build and check hash chains and Merkle proofs, and explain what a hash does and doesn't prove (BC1).
2. PO2 Explain public and private keys, sign and verify messages, recover a signer's address, and stop replayed or reused signatures (BC2).
3. PO3 Design multi-signature approvals with thresholds, revocation and owner changes, and plan how keys are kept, backed up and recovered (BC3).
4. PO4 Explain how a shared ledger agrees: blocks, forks, proof of work and proof of stake, and when a transaction can be treated as final (BC4).
5. PO5 Work with Ethereum accounts, transactions, nonces, gas, events and networks, and use practice and test networks safely (BC5).
6. PO6 Decide honestly whether a problem needs a blockchain, and compare public chains, layer 2 networks, permissioned ledgers and ordinary databases (BC6).
7. PO7 Write smart contracts in Solidity with clear state, access control, custom errors, events and safe payments (BC7).
8. PO8 Test and secure smart contracts against reentrancy, access-control mistakes, failed payments and broken invariants, and write a security review (BC8).
9. PO9 Build apps that check the network, keep keys out of code, show amounts exactly, read events in ranges, wait for confirmations, manage nonces and explain errors (BC9).
10. PO10 Combine all of this in three tested projects and a capstone on the SakhiKosh practice kit (BC10).

The coverage of each outcome by lessons, quizzes and the path test is listed at the end of this guide.

How it compares with neighbouring paths

The difference in one line: other paths build systems one organisation runs and can correct; this path builds shared records that several parties check, where mistakes are hard to undo.

Before you start: core lessons to know

The path opens after you pass the final examination. These core modules matter most; revisit them if the entry diagnostic shows a gap:

Setup guide

Tested on 2 November 2026 on Linux. Versions change, so check each tool's official page when you install. The practice kit pins its packages in package-lock.json, so everyone installs the same versions.

Install:

1. Install Node.js 22 or newer from nodejs.org. Check: node --version prints v22 or newer.
2. Download the starter kit from this path's Projects page and unzip it. In a terminal, go to the sakhikosh folder.
3. Run npm ci. It installs 195 packages (about 229 MB) in under a minute on a good connection.
4. Run npm run compile. It should compile the contracts without errors.

Verify your setup: run npm test in the sakhikosh folder. In the starter all 28 tests fail on purpose; what matters is that the tests start, list 28 checks and finish, which takes about 12 seconds including compiling.

Windows and macOS: we could only verify Linux on 2 November 2026, so Windows and macOS are marked "not verified" in the kit. The commands are the same.

Hardware and accounts

• Computer: a laptop from the last 6 to 8 years with 4 GB of memory and about 500 MB of free disk space.

• No wallet, cryptocurrency or paid accounts are needed. The kit runs a practice network on your own computer, with test ether that has no value. SakhiKosh's savings group, its members (listed by ID only) and their deposits are invented. Passing the tests shows your code handles these cases; it doesn't prove a contract is safe to hold real money. That needs a professional audit, which this path doesn't provide.

• Optional: if you try a public test network, use a fresh wallet with test ether only, keep its recovery phrase out of every file and screenshot, and don't send real money to anything you build here.

Workload

Times are realistic estimates for a learner who has finished the core programme. They are not measured averages.

At 8 to 10 hours a week that is about 13 to 18 weeks.

How completion works

You complete the path when all of these are true, as shown on your completion record:

• every lesson is marked done;
• every module quiz is passed (70% or more);
• the path test is passed (70% or more);
• the three projects and the capstone are self-checked complete, with evidence links and your explanations.

Projects are self-checked for now: you tick the marking guide yourself and save your evidence on this device. Review by a team is planned for later; until then nothing on this site says a reviewer has approved your work. Progress is saved in this browser only, so download a backup from My progress now and then.

Outcome coverage