Earlier we introduced a new package hashing mechanism that is compatible
with both packed and unpacked packages, because it's a hash of the
contents of the package rather than of the archive it's delivered in.
However, we were using that only for the local selections file and not
for any remote package authentication yet.
The provider network mirrors protocol includes new-style hashes as a step
towards transitioning over to the new hash format in all cases, so this
new authenticator is here in preparation for verifying the checksums of
packages coming from network mirrors, for mirrors that support them.
For now this leaves us in a kinda confusing situation where we have both
NewPackageHashAuthentication for the new style and
NewArchiveChecksumAuthentication for the old style, which for the moment
is represented only by a doc comment on the latter. Hopefully we can
remove NewArchiveChecksumAuthentication in a future commit, if we can
get the registry updated to use the new hashing format.
Providers installed from the registry are accompanied by a list of
checksums (the "SHA256SUMS" file), which is cryptographically signed to
allow package authentication. The process of verifying this has multiple
steps:
- First we must verify that the SHA256 hash of the package archive
matches the expected hash. This could be done for local installations
too, in the future.
- Next we ensure that the expected hash returned as part of the registry
API response matches an entry in the checksum list.
- Finally we verify the cryptographic signature of the checksum list,
using the public keys provided by the registry.
Each of these steps is implemented as a separate PackageAuthentication
type. The local archive installation mechanism uses only the archive
checksum authenticator, and the HTTP installation uses all three in the
order given.
The package authentication system now also returns a result value, which
is used by command/init to display the result of the authentication
process.
There are three tiers of signature, each of which is presented
differently to the user:
- Signatures from the embedded HashiCorp public key indicate that the
provider is officially supported by HashiCorp;
- If the signing key is not from HashiCorp, it may have an associated
trust signature, which indicates that the provider is from one of
HashiCorp's trusted partners;
- Otherwise, if the signature is valid, this is a community provider.
Earlier on in the stubbing of this package we realized that it wasn't
going to be possible to populate the authentication-related bits for all
packages because the relevant metadata just isn't available for packages
that are already local.
However, we just moved ahead with that awkward design at the time because
we needed to get other work done, and so we've been mostly producing
PackageMeta values with all-zeros hashes and just ignoring them entirely
as a temporary workaround.
This is a first step towards what is hopefully a more intuitive model:
authentication is an optional thing in a PackageMeta that is currently
populated only for packages coming from a registry.
So far this still just models checking a SHA256 hash, which is not a
sufficient set of checks for a real release but hopefully the "real"
implementation is a natural iteration of this starting point, and if not
then at least this interim step is a bit more honest about the fact that
Authentication will not be populated on every PackageMeta.
Martin Atkins