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https://github.com/sigstore/sigstore-python

A Sigstore client written in Python
https://github.com/sigstore/sigstore-python

codesigning python security supply-chain

Last synced: about 3 hours ago
JSON representation

A Sigstore client written in Python

Host: GitHub
URL: https://github.com/sigstore/sigstore-python
Owner: sigstore
License: other
Created: 2022-01-13T17:29:37.000Z (almost 3 years ago)
Default Branch: main
Last Pushed: 2024-12-05T20:17:45.000Z (8 days ago)
Last Synced: 2024-12-08T21:18:32.128Z (5 days ago)
Topics: codesigning, python, security, supply-chain
Language: Python
Homepage: https://pypi.org/p/sigstore
Size: 2.07 MB
Stars: 234
Watchers: 9
Forks: 49
Open Issues: 35
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Codeowners: CODEOWNERS

Awesome Lists containing this project

README

sigstore-python
===============

![CI](https://github.com/sigstore/sigstore-python/workflows/CI/badge.svg)
[![PyPI version](https://badge.fury.io/py/sigstore.svg)](https://pypi.org/project/sigstore)
[![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/sigstore/sigstore-python/badge)](https://securityscorecards.dev/viewer/?uri=github.com/sigstore/sigstore-python)
[![SLSA](https://slsa.dev/images/gh-badge-level3.svg)](https://slsa.dev/)
![Conformance Tests](https://github.com/sigstore/sigstore-python/workflows/Conformance%20Tests/badge.svg)
[![Documentation](https://github.com/sigstore/sigstore-python/actions/workflows/docs.yml/badge.svg)](https://sigstore.github.io/sigstore-python)

`sigstore` is a Python tool for generating and verifying Sigstore signatures.
You can use it to sign and verify Python package distributions, or anything
else!

## Index

* [Features](#features)
* [Installation](#installation)
* [GitHub Actions](#github-actions)
* [Usage](#usage)
* [Signing](#signing)
* [Verifying](#verifying)
* [Generic identities](#generic-identities)
* [Signatures from GitHub Actions](#signatures-from-github-actions)
* [Advanced usage](#advanced-usage)
* [Example uses](#example-uses)
* [Signing with ambient credentials](#signing-with-ambient-credentials)
* [Signing with an email identity](#signing-with-an-email-identity)
* [Signing with an explicit identity token](#signing-with-an-explicit-identity-token)
* [Verifying against a bundle](#verifying-against-a-bundle)
* [Offline verification](#offline-verification)
* [Verifying a digest instead of a file](#verifying-a-digest-instead-of-a-file)
* [Verifying signatures from GitHub Actions](#verifying-signatures-from-github-actions)
* [Licensing](#licensing)
* [Community](#community)
* [Contributing](#contributing)
* [Code of Conduct](#code-of-conduct)
* [Security](#security)
* [SLSA Provenance](#slsa-provenance)

## Features

* Support for keyless signature generation and verification with [Sigstore](https://www.sigstore.dev/)
* Support for signing with ["ambient" OpenID Connect identities](https://github.com/sigstore/sigstore-python#signing-with-ambient-credentials)
* A comprehensive [CLI](https://github.com/sigstore/sigstore-python#usage) and corresponding
[importable Python API](https://sigstore.github.io/sigstore-python)

## Installation

`sigstore` requires Python 3.9 or newer, and can be installed directly via `pip`:

```console
python -m pip install sigstore
```

Optionally, to install `sigstore` and all its dependencies with [hash-checking mode](https://pip.pypa.io/en/stable/topics/secure-installs/#hash-checking-mode) enabled, run the following:

```console
python -m pip install -r https://raw.githubusercontent.com/sigstore/sigstore-python/main/install/requirements.txt
```

This installs the requirements file located [here](https://github.com/sigstore/sigstore-python/blob/main/install/requirements.txt), which is kept up-to-date.

### GitHub Actions

`sigstore-python` has [an official GitHub Action](https://github.com/sigstore/gh-action-sigstore-python)!

You can install it from the
[GitHub Marketplace](https://github.com/marketplace/actions/gh-action-sigstore-python), or
add it to your CI manually:

```yaml
jobs:
sigstore-python:
steps:
- uses: sigstore/[email protected]
with:
inputs: foo.txt
```

See the
[action documentation](https://github.com/sigstore/gh-action-sigstore-python/blob/main/README.md)
for more details and usage examples.

## Usage

For Python API usage, see our [documentation](https://sigstore.github.io/sigstore-python/).

You can run `sigstore` as a standalone program, or via `python -m`:

```console
sigstore --help
python -m sigstore --help
```

Top-level:

```
usage: sigstore [-h] [-v] [-V] [--staging | --trust-config FILE] COMMAND ...

a tool for signing and verifying Python package distributions

positional arguments:
COMMAND the operation to perform
attest sign one or more inputs using DSSE
sign sign one or more inputs
verify verify one or more inputs
get-identity-token
retrieve and return a Sigstore-compatible OpenID
Connect token
plumbing developer-only plumbing operations

optional arguments:
-h, --help show this help message and exit
-v, --verbose run with additional debug logging; supply multiple
times to increase verbosity (default: 0)
-V, --version show program's version number and exit
--staging Use sigstore's staging instances, instead of the
default production instances (default: False)
--trust-config FILE The client trust configuration to use (default: None)
```

### Signing

```
usage: sigstore sign [-h] [-v] [--identity-token TOKEN] [--oidc-client-id ID]
[--oidc-client-secret SECRET]
[--oidc-disable-ambient-providers] [--oidc-issuer URL]
[--oauth-force-oob] [--no-default-files]
[--signature FILE] [--certificate FILE] [--bundle FILE]
[--output-directory DIR] [--overwrite]
FILE [FILE ...]

positional arguments:
FILE The file to sign

optional arguments:
-h, --help show this help message and exit
-v, --verbose run with additional debug logging; supply multiple
times to increase verbosity (default: 0)

OpenID Connect options:
--identity-token TOKEN
the OIDC identity token to use (default: None)
--oidc-client-id ID The custom OpenID Connect client ID to use during
OAuth2 (default: sigstore)
--oidc-client-secret SECRET
The custom OpenID Connect client secret to use during
OAuth2 (default: None)
--oidc-disable-ambient-providers
Disable ambient OpenID Connect credential detection
(e.g. on GitHub Actions) (default: False)
--oidc-issuer URL The OpenID Connect issuer to use (conflicts with
--staging) (default: https://oauth2.sigstore.dev/auth)
--oauth-force-oob Force an out-of-band OAuth flow and do not
automatically start the default web browser (default:
False)

Output options:
--no-default-files Don't emit the default output files
({input}.sigstore.json) (default: False)
--signature FILE, --output-signature FILE
Write a single signature to the given file; does not
work with multiple input files (default: None)
--certificate FILE, --output-certificate FILE
Write a single certificate to the given file; does not
work with multiple input files (default: None)
--bundle FILE Write a single Sigstore bundle to the given file; does
not work with multiple input files (default: None)
--output-directory DIR
Write default outputs to the given directory
(conflicts with --signature, --certificate, --bundle)
(default: None)
--overwrite Overwrite preexisting signature and certificate
outputs, if present (default: False)
```

### Signing with DSSE envelopes

```
usage: sigstore attest [-h] [-v] --predicate FILE --predicate-type TYPE
[--identity-token TOKEN] [--oidc-client-id ID]
[--oidc-client-secret SECRET]
[--oidc-disable-ambient-providers] [--oidc-issuer URL]
[--oauth-force-oob] [--bundle FILE] [--overwrite]
FILE [FILE ...]

positional arguments:
FILE The file to sign

optional arguments:
-h, --help show this help message and exit
-v, --verbose run with additional debug logging; supply multiple
times to increase verbosity (default: 0)

DSSE options:
--predicate FILE Path to the predicate file (default: None)
--predicate-type TYPE
Specify a predicate type
(https://slsa.dev/provenance/v0.2,
https://slsa.dev/provenance/v1) (default: None)

Output options:
--bundle FILE Write a single Sigstore bundle to the given file; does
not work with multiple input files (default: None)
--overwrite Overwrite preexisting bundle outputs, if present
(default: False)
```

### Verifying

#### Generic identities

This is the most common verification done with `sigstore`, and therefore
the one you probably want: you can use it to verify that a signature was
produced by a particular identity (like `[email protected]`), as attested
to by a particular OIDC provider (like `https://github.com/login/oauth`).

```
usage: sigstore verify identity [-h] [-v] [--certificate FILE]
[--signature FILE] [--bundle FILE] [--offline]
--cert-identity IDENTITY --cert-oidc-issuer
URL
FILE_OR_DIGEST [FILE_OR_DIGEST ...]

optional arguments:
-h, --help show this help message and exit
-v, --verbose run with additional debug logging; supply multiple
times to increase verbosity (default: 0)

Verification inputs:
--certificate FILE, --cert FILE
The PEM-encoded certificate to verify against; not
used with multiple inputs (default: None)
--signature FILE The signature to verify against; not used with
multiple inputs (default: None)
--bundle FILE The Sigstore bundle to verify with; not used with
multiple inputs (default: None)
FILE_OR_DIGEST The file path or the digest to verify. The digest
should start with the 'sha256:' prefix.

Verification options:
--offline Perform offline verification; requires a Sigstore
bundle (default: False)
--cert-identity IDENTITY
The identity to check for in the certificate's Subject
Alternative Name (default: None)
--cert-oidc-issuer URL
The OIDC issuer URL to check for in the certificate's
OIDC issuer extension (default: None)
```

#### Signatures from GitHub Actions

If your signatures are coming from GitHub Actions (e.g., a workflow
that uses its [ambient credentials](#signing-with-ambient-credentials)),
then you can use the `sigstore verify github` subcommand to verify
claims more precisely than `sigstore verify identity` allows:

```
usage: sigstore verify github [-h] [-v] [--certificate FILE]
[--signature FILE] [--bundle FILE] [--offline]
[--cert-identity IDENTITY] [--trigger EVENT]
[--sha SHA] [--name NAME] [--repository REPO]
[--ref REF]
FILE_OR_DIGEST [FILE_OR_DIGEST ...]

optional arguments:
-h, --help show this help message and exit
-v, --verbose run with additional debug logging; supply multiple
times to increase verbosity (default: 0)

Verification options:
--offline Perform offline verification; requires a Sigstore
bundle (default: False)
--cert-identity IDENTITY
The identity to check for in the certificate's Subject
Alternative Name (default: None)
--trigger EVENT The GitHub Actions event name that triggered the
workflow (default: None)
--sha SHA The `git` commit SHA that the workflow run was invoked
with (default: None)
--name NAME The name of the workflow that was triggered (default:
None)
--repository REPO The repository slug that the workflow was triggered
under (default: None)
--ref REF The `git` ref that the workflow was invoked with
(default: None)
```

## Advanced usage

### Configuring a custom root of trust ("BYO PKI")

Apart from the default and "staging" Sigstore instances, `sigstore` also
supports "BYO PKI" setups, where a user maintains their own Sigstore
instance services.

These are supported via the `--trust-config` flag, which accepts a
JSON-formatted file conforming to the `ClientTrustConfig` message
in the [Sigstore protobuf specs](https://github.com/sigstore/protobuf-specs).
This file configures the entire Sigstore instance state, *including* the URIs
used to access the CA and artifact transparency services as well as the
cryptographic root of trust itself.

To use a custom client config, prepend `--trust-config` to any `sigstore`
command:

```console
$ sigstore --trust-config custom.trustconfig.json sign foo.txt
$ sigstore --trust-config custom.trustconfig.json verify identity foo.txt ...
```

## Example uses

`sigstore` supports a wide variety of workflows and usages. Some common ones are
provided below.

### Signing with ambient credentials

For environments that support OpenID Connect, `sigstore` supports ambient credential
detection. This includes many popular CI platforms and cloud providers. See the full list of
supported environments [here](https://github.com/di/id#supported-environments).

Sign a single file (`foo.txt`) using an ambient OpenID Connect credential,
saving the bundle to `foo.txt.sigstore.json`:

```console
$ python -m sigstore sign foo.txt
```

### Signing with an email identity

`sigstore` can use an OAuth2 + OpenID flow to establish an email identity,
allowing you to request signing certificates that attest to control over
that email.

Sign a single file (`foo.txt`) using the OAuth2 flow, saving the
bundle to `foo.txt.sigstore.json`:

```console
$ python -m sigstore sign foo.txt
```

By default, `sigstore` attempts to do
[ambient credential detection](#signing-with-ambient-credentials), which may preempt
the OAuth2 flow. To force the OAuth2 flow, you can explicitly disable ambient detection:

```console
$ python -m sigstore sign --oidc-disable-ambient-providers foo.txt
```

### Signing with an explicit identity token

If you can't use an ambient credential or the OAuth2 flow, you can pass a pre-created
identity token directly into `sigstore sign`:

```console
$ python -m sigstore sign --identity-token YOUR-LONG-JWT-HERE foo.txt
```

Note that passing a custom identity token does not circumvent Fulcio's requirements,
namely the Fulcio's supported identity providers and the claims expected within the token.

### Verifying against a bundle

By default, `sigstore verify identity` will attempt to find a `.sigstore.json`
or `.sigstore` in the same directory as the file being verified:

```console
# looks for foo.txt.sigstore.json
$ python -m sigstore verify identity foo.txt \
--cert-identity '[email protected]' \
--cert-oidc-issuer 'https://github.com/login/oauth'
```

Multiple files can be verified at once:

```console
# looks for {foo,bar}.txt.sigstore.json
$ python -m sigstore verify identity foo.txt bar.txt \
--cert-identity '[email protected]' \
--cert-oidc-issuer 'https://github.com/login/oauth'
```

### Offline verification

> [!IMPORTANT]
> Because `--offline` disables trust root updates, `sigstore-python` falls back
> to the latest cached trust root or, if none exists, the trust root baked
> into `sigstore-python` itself. Like with any other offline verification,
> this means that users may miss trust root changes (such as new root keys,
> or revocations) unless they separately keep the trust root up-to-date.
>
> Users who need to operationalize offline verification may wish to do this
> by distributing their own trust configuration; see
> [Configuring a custom root of trust](#configuring-a-custom-root-of-trust-byo-pki).

During verification, there are two kinds of network access that `sigstore-python`
*can* perform:

1. When verifying against "detached" materials (e.g. separate `.crt` and `.sig`
files), `sigstore-python` can perform an online transparency log lookup.
2. By default, during all verifications, `sigstore-python` will attempt to
refresh the locally cached root of trust via a TUF update.

When performing bundle verification (i.e. `.sigstore` or `.sigstore.json`),
(1) does not apply. However, (2) can still result in online accesses.

To perform **fully** offline verification, pass `--offline` to your
`sigstore verify` subcommand:

```bash
$ python -m sigstore verify identity foo.txt \
--offline \
--cert-identity '[email protected]' \
--cert-oidc-issuer 'https://github.com/login/oauth'
```

Alternatively, users may choose to bypass TUF entirely by passing
an entire trust configuration to `sigstore-python` via `--trust-config`:

```bash
$ python -m sigstore --trust-config public.trustconfig.json verify identity ...
```

This will similarly result in fully offline operation, as the trust
configuration contains a full trust root.

### Verifying a digest instead of a file

`sigstore-python` supports verifying digests directly, without requiring the artifact to be
present. The digest should be prefixed with the `sha256:` string:

```console
$ python -m sigstore verify identity sha256:ce8ab2822671752e201ea1e19e8c85e73d497e1c315bfd9c25f380b7625d1691 \
--cert-identity '[email protected]' \
--cert-oidc-issuer 'https://github.com/login/oauth'
--bundle 'foo.txt.sigstore.json'
```

### Verifying signatures from GitHub Actions

`sigstore verify github` can be used to verify claims specific to signatures coming from GitHub
Actions. `sigstore-python` signs releases via GitHub Actions, so the examples below are working
examples of how you can verify a given `sigstore-python` release.

When using `sigstore verify github`, you must pass `--cert-identity` or `--repository`, or both.
Unlike `sigstore verify identity`, `--cert-oidc-issuer` is **not** required (since it's
inferred to be GitHub Actions).

Verifying with `--cert-identity`:

Verifying with `--repository`:

```console
$ python -m sigstore verify github sigstore-0.10.0-py3-none-any.whl \
--bundle sigstore-0.10.0-py3-none-any.whl.bundle \
--repository sigstore/sigstore-python
```

Additional GitHub Actions specific claims can be verified like so:

```console
$ python -m sigstore verify github sigstore-0.10.0-py3-none-any.whl \
--bundle sigstore-0.10.0-py3-none-any.whl.bundle \
--cert-identity https://github.com/sigstore/sigstore-python/.github/workflows/release.yml@refs/tags/v0.10.0 \
--trigger release \
--sha 66581529803929c3ccc45334632ccd90f06e0de4 \
--name Release \
--repository sigstore/sigstore-python \
--ref refs/tags/v0.10.0
```

## Licensing

`sigstore` is licensed under the Apache 2.0 License.

## Community

`sigstore-python` is developed as part of the [Sigstore](https://sigstore.dev) project.

We also use a [Slack channel](https://sigstore.slack.com)!
Click [here](https://join.slack.com/t/sigstore/shared_invite/zt-mhs55zh0-XmY3bcfWn4XEyMqUUutbUQ) for the invite link.

## Contributing

See [the contributing docs](https://github.com/sigstore/.github/blob/main/CONTRIBUTING.md) for details.

## Code of Conduct

Everyone interacting with this project is expected to follow the
[sigstore Code of Conduct](https://github.com/sigstore/.github/blob/main/CODE_OF_CONDUCT.md).

## Security

Should you discover any security issues, please refer to sigstore's [security
process](https://github.com/sigstore/.github/blob/main/SECURITY.md).

### SLSA Provenance
This project emits a SLSA provenance on its release! This enables you to verify the integrity
of the downloaded artifacts and ensured that the binary's code really comes from this source code.

To do so, please follow the instructions [here](https://github.com/slsa-framework/slsa-github-generator#verification-of-provenance).