To ensure the integrity of packages you download from the public npm registry, or any registry that supports signatures, you can verify the registry signatures of downloaded packages using the npm CLI.
npm install or npm ci
Registry signatures can be verified using the following audit command:
npm audit signatures Example response if all installed versions have valid registry signatures:
audited 1640 packages in 2s 1640 have verified registry signatures
The CLI will error if packages don't have signatures and if the package registry supports signatures. This could mean an attacker might be trying to circumvent signature verification. You can check if the registry supports signatures by requesting the public signing keys from registry-host.tld/-/npm/v1/keys.
Example response if some versions have missing registry signatures:
audited 1640 packages in 2s 1405 packages have verified registry signatures 235 packages have missing registry signatures but the registry is providing signing keys: [email protected] (https://registry.npmjs.org/) ...
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https://docs.npmjs.com/verifying-registry-signatures