Rendered from docs/INSTALLATION.md at build time without changing its status. The repository source controls if this presentation differs.

Install Verifier#

Verifier implements the Verifier Standard (VSTD), a verification-domain language for portable, bounded, refutable evidence about computational claims.

Install the released package#

Use Python 3.10 or newer in a fresh virtual environment. The base runtime has no required third-party dependencies. These instructions pin release 1.5.0 from the Python Package Index (PyPI).

python -m venv .venv

Activate the environment on Windows PowerShell:

.venv\Scripts\Activate.ps1

Or on macOS and Linux:

source .venv/bin/activate

Install and inspect the version:

python -m pip install verifier-standard==1.5.0
python -c "import verifier; print(verifier.__version__)"
vstd --help

The version command should print 1.5.0. The distribution name is verifier-standard; the Python import is verifier; the cross-platform command is vstd. On Windows, the name verifier can resolve to Windows Driver Verifier, so use vstd for this package.

Check the defensive demo#

vstd demo

The demo exercises four expected defensive outcomes, including rejection and preservation of UNKNOWN. Its [DEMO OK] result means those expectations matched for these specimens. It is not an assurance claim about your own application.

Continue with your first receipt to capture a small computation.

Use Python directly#

The application programming interface (API) is exposed through the top-level verifier package. For example, canonical digesting produces the same digest for these two mappings, whose key order differs:

from verifier import compute_canonical_digest

left = {"claim": "example", "value": 3}
right = {"value": 3, "claim": "example"}
assert compute_canonical_digest(left) == compute_canonical_digest(right)

This checks canonical digest agreement for these payloads. It does not establish the truth of a claim, authenticate its producer, or create a complete receipt. See the API stability policy before depending on an export.

Choose a documentation coordinate#

The documentation portal provides a released 1.5.0 reference generated from the corresponding Git tag and a separate current repository reference. Repository source can include commands that the released distribution does not yet contain. Use the version selector or the Package reference · 1.5.0 navigation group when working with the package above.

To work on repository changes, follow the repository walkthrough. Avoid mixing an editable checkout and a released package in the same environment when comparing behavior.

Troubleshoot the environment#

If vstd is unavailable, confirm the virtual environment is active and inspect the package in that same interpreter:

python -m pip show verifier-standard
python -c "import sys, verifier; print(sys.executable); print(verifier.__file__)"

An unexpected import path can indicate another installed package or a local file named verifier.py. Resolve that shadowing before interpreting a command result.