go-tuf

This is a Go implementation of The Update Framework (TUF), a framework for securing software update systems.

Directory layout

A TUF repository has the following directory layout:

.
├── keys
├── repository
│   └── targets
└── staged
    └── targets

The directories contain the following files:

• keys/ - signing keys (optionally encrypted) with filename pattern ROLE.json
• repository/ - signed metadata files
• repository/targets/ - hashed target files
• staged/ - either signed, unsigned or partially signed metadata files
• staged/targets/ - unhashed target files

CLI

go-tuf provides a CLI for managing a local TUF repository.

Install

go-tuf is tested on Go versions 1.18.

go install github.com/theupdateframework/go-tuf/cmd/tuf@latest

Commands

tuf init [--consistent-snapshot=false]

Initializes a new repository.

This is only required if the repository should not generate consistent snapshots (i.e. by passing --consistent-snapshot=false). If consistent snapshots should be generated, the repository will be implicitly initialized to do so when generating keys.

tuf gen-key [--expires=<days>] <role>

Prompts the user for an encryption passphrase (unless the --insecure-plaintext flag is set), then generates a new signing key and writes it to the relevant key file in the keys directory. It also stages the addition of the new key to the root metadata file. Alternatively, passphrases can be set via environment variables in the form of TUF_{{ROLE}}_PASSPHRASE

tuf revoke-key [--expires=<days>] <role> <id>

Revoke a signing key

The key will be removed from the root metadata file, but the key will remain in the "keys" directory if present.

tuf add [<path>...]

Hashes files in the staged/targets directory at the given path(s), then updates and stages the targets metadata file. Specifying no paths hashes all files in the staged/targets directory.

tuf remove [<path>...]

Stages the removal of files with the given path(s) from the targets metadata file (they get removed from the filesystem when the change is committed). Specifying no paths removes all files from the targets metadata file.

tuf snapshot [--expires=<days>]

Expects a staged, fully signed targets metadata file and stages an appropriate snapshot metadata file. Optionally one can set number of days after which the snapshot metadata will expire.

tuf timestamp [--expires=<days>]

Stages an appropriate timestamp metadata file. If a snapshot metadata file is staged, it must be fully signed. Optionally one can set number of days after which the timestamp metadata will expire.

tuf sign <metadata>

Signs the given role's staged metadata file with all keys present in the keys directory for that role.

tuf commit

Verifies that all staged changes contain the correct information and are signed to the correct threshold, then moves the staged files into the repository directory. It also removes any target files which are not in the targets metadata file.

tuf regenerate [--consistent-snapshot=false]

Note: Not supported yet

Recreates the targets metadata file based on the files in repository/targets.

tuf clean

Removes all staged metadata files and targets.

tuf root-keys

Outputs a JSON serialized array of root keys to STDOUT. The resulting JSON should be distributed to clients for performing initial updates.

tuf set-threshold <role> <threshold>

Sets role's threshold (required number of keys for signing) to threshold.

tuf get-threshold <role>

Outputs role's threshold (required number of keys for signing).

tuf change-passphrase <role>

Changes the passphrase for given role keys file. The CLI supports reading both the existing and the new passphrase via the following environment variables - TUF_{{ROLE}}_PASSPHRASE and respectively TUF_NEW_{{ROLE}}_PASSPHRASE

tuf payload <metadata>

Outputs the metadata file for a role in a ready-to-sign (canonicalized) format.

See also tuf sign-payload and tuf add-signatures.

tuf sign-payload --role=<role> <path>

Sign a file (outside of the TUF repo) using keys (in the TUF keys database, typically produced by tuf gen-key) for the given role (from the TUF repo).

Typically, path will be a file containing the output of tuf payload.

See also tuf add-signatures.

tuf add-signatures --signatures <sig_file> <metadata>

Adds signatures (the output of tuf sign-payload) to the given role metadata file.

If the signature does not verify, it will not be added.

tuf status --valid-at <date> <role>

Check if the role's metadata will be expired on the given date.

Usage of environment variables

The tuf CLI supports receiving passphrases via environment variables in the form of TUF_{{ROLE}}_PASSPHRASE for existing ones and TUF_NEW_{{ROLE}}_PASSPHRASE for setting new ones.

For a list of supported commands, run tuf help from the command line.

Examples

The following are example workflows for managing a TUF repository with the CLI.

The tree commands do not need to be run, but their output serve as an illustration of what files should exist after performing certain commands.

Although only two machines are referenced (i.e. the "root" and "repo" boxes), the workflows can be trivially extended to many signing machines by copying staged changes and signing on each machine in turn before finally committing.

Some key IDs are truncated for illustrative purposes.

Create signed root metadata file

Generate a root key on the root box:

$ tuf gen-key root
Enter root keys passphrase:
Repeat root keys passphrase:
Generated root key with ID 184b133f

$ tree .
.
├── keys
│   └── root.json
├── repository
└── staged
    ├── root.json
    └── targets

Copy staged/root.json from the root box to the repo box and generate targets, snapshot and timestamp keys:

$ tree .
.
├── keys
├── repository
└── staged
    ├── root.json
    └── targets

$ tuf gen-key targets
Enter targets keys passphrase:
Repeat targets keys passphrase:
Generated targets key with ID 8cf4810c

$ tuf gen-key snapshot
Enter snapshot keys passphrase:
Repeat snapshot keys passphrase:
Generated snapshot key with ID 3e070e53

$ tuf gen-key timestamp
Enter timestamp keys passphrase:
Repeat timestamp keys passphrase:
Generated timestamp key with ID a3768063

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
└── staged
    ├── root.json
    └── targets

Copy staged/root.json from the repo box back to the root box and sign it:

$ tree .
.
├── keys
│   ├── root.json
├── repository
└── staged
    ├── root.json
    └── targets

$ tuf sign root.json
Enter root keys passphrase:

The staged root.json can now be copied back to the repo box ready to be committed alongside other metadata files.

Alternate signing flow

Instead of manually copying root.json into the TUF repository on the root box, you can use the tuf payload, tuf sign-payload, tuf add-signatures flow.

On the repo box, get the root.json payload in a canonical format:

$ tuf payload root.json > root.json.payload

Copy root.json.payload to the root box and sign it:

$ tuf sign-payload --role=root root.json.payload > root.json.sigs
Enter root keys passphrase:

Copy root.json.sigs back to the repo box and import the signatures:

$ tuf add-signatures --signatures root.json.sigs root.json

This achieves the same state as the above flow for the repo box:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
└── staged
    ├── root.json
    └── targets

Add a target file

Assuming a staged, signed root metadata file and the file to add exists at staged/targets/foo/bar/baz.txt:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
└── staged
    ├── root.json
    └── targets
        └── foo
            └── bar
                └── baz.txt

$ tuf add foo/bar/baz.txt
Enter targets keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
└── staged
    ├── root.json
    ├── targets
    │   └── foo
    │       └── bar
    │           └── baz.txt
    └── targets.json

$ tuf snapshot
Enter snapshot keys passphrase:

$ tuf timestamp
Enter timestamp keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
└── staged
    ├── root.json
    ├── snapshot.json
    ├── targets
    │   └── foo
    │       └── bar
    │           └── baz.txt
    ├── targets.json
    └── timestamp.json

$ tuf commit

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

Remove a target file

Assuming the file to remove is at repository/targets/foo/bar/baz.txt:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

$ tuf remove foo/bar/baz.txt
Enter targets keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged
    └── targets.json

$ tuf snapshot
Enter snapshot keys passphrase:

$ tuf timestamp
Enter timestamp keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged
    ├── snapshot.json
    ├── targets.json
    └── timestamp.json

$ tuf commit

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
└── staged

Regenerate metadata files based on targets tree (Note: Not supported yet)

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

$ tuf regenerate
Enter targets keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged
    └── targets.json

$ tuf snapshot
Enter snapshot keys passphrase:

$ tuf timestamp
Enter timestamp keys passphrase:

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged
    ├── snapshot.json
    ├── targets.json
    └── timestamp.json

$ tuf commit

$ tree .
.
├── keys
│   ├── snapshot.json
│   ├── targets.json
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

Update timestamp.json

$ tree .
.
├── keys
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

$ tuf timestamp
Enter timestamp keys passphrase:

$ tree .
.
├── keys
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged
    └── timestamp.json

$ tuf commit

$ tree .
.
├── keys
│   └── timestamp.json
├── repository
│   ├── root.json
│   ├── snapshot.json
│   ├── targets
│   │   └── foo
│   │       └── bar
│   │           └── baz.txt
│   ├── targets.json
│   └── timestamp.json
└── staged

Adding a new root key

Copy staged/root.json to the root box and generate a new root key on the root box:

$ tuf gen-key root
$ tuf sign root.json

Copy staged/root.json from the root box and commit:

$ tuf commit

Rotating root key(s)

Copy staged/root.json to the root box to do the rotation, where abcd is the keyid of the key that is being replaced:

$ tuf gen-key root
$ tuf revoke-key root abcd
$ tuf sign root.json

Note that revoke-key removes the old key from root.json, but the key remains in the keys/ directory on the root box as it is needed to sign the next root.json. After this signing is done, the old key may be removed from keys/. Any number of keys may be added or revoked during this step, but ensure that at least a threshold of valid keys remain.

Copy staged/root.json from the root box to commit:

$ tuf commit

Client

For the client package, see https://godoc.org/github.com/theupdateframework/go-tuf/client.

For the client CLI, see https://github.com/theupdateframework/go-tuf/tree/master/cmd/tuf-client.

Contributing and Development

For local development, go-tuf requires Go version 1.18.

The Python interoperability tests require Python 3 (available as python on the $PATH) and the python-tuf package installed (pip install tuf). To update the data for these tests requires Docker and make (see test data README.md for details).

Please see CONTRIBUTING.md for contribution guidelines before making your first contribution!

Comparison to other implementations

There are TUF implementations in a variety of programming languages. Some other Go implementations of TUF include:

• Notary: A version of TUF designed specifically for publishing and managing trusted collections of content. It was used by Docker Content Trust, and has since been superseded by the Notation project. In contrast, go-tuf is a direct implementation of TUF and has been updated to conform to 1.0.0 of the TUF specification.