BA-01 · LESSON 06

Open-source verification

KEY DEFINITIONS

Terms used in this lesson

SHA-256: A cryptographic hash function used throughout Bitcoin to produce fixed-size 256-bit digests.
ASCII: A standard mapping between common text characters and byte values.

Anyone can inspect the rules, run the software, and reproduce a result. Security comes from independent checks rather than trust in one operator.

45 min Difficulty 1/5 Not started

VISUAL MODEL

See the whole mechanism before going step by step

Use the diagrams to orient yourself. Then the guided explanation below teaches every part in depth.

4 explanatory views

CONCEPT-SPECIFIC MAP · state machineOne valid action transforms a known stateSelect any state to inspect its exact role.

RELATIONSHIP MAPOrdered mechanism flow

01
BEFOREKnown state
Identify the facts and objects that exist before the action.
02
ACTIONOpen-source verification
The Open-source verification lesson isolates the event that proposes a change.
03
RULEDeterministic check
The enforcing rule accepts or rejects the proposed transition.
04
AFTERSuccessor state
Accepted work creates a new state without silently changing the prior facts.
05
FAILUREState unchanged
A failed condition must not produce a partially accepted successor.

Rule shown: A valid transition names the prior state, action, enforcing rule, and successor state.

STAGE 1 OF 5BEFORE: Known state

Identify the facts and objects that exist before the action.

Governing relationship: A valid transition names the prior state, action, enforcing rule, and successor state. Complete path: 1. BEFORE, Known state. Identify the facts and objects that exist before the action. 2. ACTION, Open-source verification. The Open-source verification lesson isolates the event that proposes a change. 3. RULE, Deterministic check. The enforcing rule accepts or rejects the proposed transition. 4. AFTER, Successor state. Accepted work creates a new state without silently changing the prior facts. 5. FAILURE, State unchanged. A failed condition must not produce a partially accepted successor.

1. State transitionWhat exists, what changes, and what results

BEFORE

A tool claims that SHA-256 of the ASCII bytes for abc equals a published digest.

MECHANISM

Replace a vague claim such as 'the wallet is safe' with a testable statement about one version, input, rule, and expected output.

AFTER

Verification ties a precise claim to reproducible evidence. It does not turn one passing example into proof of every property.

Text equivalent: Starting from A tool claims that SHA-256 of the ASCII bytes for abc equals a published digest. The mechanism begins when Replace a vague claim such as 'the wallet is safe' with a testable statement about one version, input, rule, and expected output. The resulting lesson is Verification ties a precise claim to reproducible evidence. It does not turn one passing example into proof of every property.

2. Mechanism pathSelect a stage to inspect its job

STAGE 1 OF 5

State the claim precisely

Replace a vague claim such as 'the wallet is safe' with a testable statement about one version, input, rule, and expected output.

Complete path: 1. State the claim precisely: Replace a vague claim such as 'the wallet is safe' with a testable statement about one version, input, rule, and expected output. 2. Inspect the relevant rule: Trace the claim to specification text, code, and tests. Reading a project name or marketing page is not evidence of runtime behavior. 3. Run an independent check: Use known inputs, record the environment, and compare the result with an independently computed expectation or canonical vector. 4. Verify the artifact: A source review does not prove that a downloaded binary came from that source. Reproducible builds and hashes help connect reviewed code to an executable artifact. 5. Track version and limits: A result applies to the tested revision and conditions. Later changes, configuration, deployment, and untested paths need separate evidence.

3. Rule and failure boundaryWhat accepts the result and where it can stop

ACCEPTED PATH

A reproducible claim needs a pinned revision, exact bytes, independent expected output, observed output, artifact hash, and an explicit evidence limit.

CHANGED CONDITION

A mismatched artifact hash breaks the source-to-binary link, and a missing revision or limitation makes the evidence record incomplete even when one output matches.

Important distinction: Publishing source code makes all claims about a program independently verified. Publication enables inspection. Verification still requires connecting a precise claim to the relevant revision, build, inputs, execution, and limitations.

Text equivalent: The accepted path is enforced by A reproducible claim needs a pinned revision, exact bytes, independent expected output, observed output, artifact hash, and an explicit evidence limit. If the required condition changes, A mismatched artifact hash breaks the source-to-binary link, and a missing revision or limitation makes the evidence record incomplete even when one output matches.

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Learn the idea

Open-source software publishes the instructions humans can inspect, but verification means independently checking what a particular program actually does with particular inputs. Reproducibility means another person can repeat a build or test and obtain the same result under documented conditions. Secure Hash Algorithm 256, shortened to SHA-256, is the exact public hash used in this lesson's reproducible vector and artifact checks.

GUIDED EXPLANATION1/5 ideas inspected

State the claim precisely

Replace a vague claim such as 'the wallet is safe' with a testable statement about one version, input, rule, and expected output.

The worked example follows the explanation

Inspect every idea above to open it.

Important distinction“Publishing source code makes all claims about a program independently verified.”

Publication enables inspection. Verification still requires connecting a precise claim to the relevant revision, build, inputs, execution, and limitations.

FINISH LEARNING FIRST

The questions unlock after every required learning activity

Inspect every guided idea, open the worked example, rebuild its mechanism, and complete the deterministic lesson tool. Your progress is saved automatically.