510 - SBOM attestation stdout (anchore#785)

add syft attest command to produce an attestation as application/vnd.in-toto+json to standard out using on disk PKI

Signed-off-by: Christopher Phillips <[email protected]>

.github/workflows/validations.yaml

@@ -348,9 +348,16 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-go-${{ env.GO_VERSION }}-
 
-      - name: (cache-miss) Bootstrap go dependencies
-        if: steps.go-cache.outputs.cache-hit != 'true'
-        run: make bootstrap-go
+      - name: Restore tool cache
+        id: tool-cache
+        uses: actions/[email protected]
+        with:
+          path: ${{ github.workspace }}/.tmp
+          key: ${{ runner.os }}-tool-${{ hashFiles('Makefile') }}
+
+      - name: (cache-miss) Bootstrap all project dependencies
+        if: steps.tool-cache.outputs.cache-hit != 'true' || steps.go-cache.outputs.cache-hit != 'true'
+        run: make bootstrap
 
       - name: Build key for tar cache
         run: make cli-fingerprint

.gitignore

@@ -36,4 +36,8 @@ bin/
 # macOS Finder metadata
 .DS_STORE
 
-*.profile
+*.profile
+
+# attestation
+cosign.key
+cosign.pub

Makefile

@@ -3,7 +3,7 @@ TEMPDIR = ./.tmp
 RESULTSDIR = test/results
 COVER_REPORT = $(RESULTSDIR)/unit-coverage-details.txt
 COVER_TOTAL = $(RESULTSDIR)/unit-coverage-summary.txt
-LINTCMD = $(TEMPDIR)/golangci-lint run --tests=false --timeout=2m --config .golangci.yaml
+LINTCMD = $(TEMPDIR)/golangci-lint run --tests=false --timeout=4m --config .golangci.yaml
 RELEASE_CMD=$(TEMPDIR)/goreleaser release --rm-dist
 SNAPSHOT_CMD=$(RELEASE_CMD) --skip-publish --snapshot
 VERSION=$(shell git describe --dirty --always --tags)
@@ -111,6 +111,7 @@ bootstrap-tools: $(TEMPDIR)
 	curl -sSfL https://raw.githubusercontent.com/anchore/chronicle/main/install.sh | sh -s -- -b $(TEMPDIR)/ v0.3.0
 	.github/scripts/goreleaser-install.sh -d -b $(TEMPDIR)/ v1.4.1
 	GOBIN="$(shell realpath $(TEMPDIR))" go install github.com/neilpa/[email protected]
+	GOBIN="$(shell realpath $(TEMPDIR))" go install github.com/sigstore/cosign/cmd/[email protected]
 
 .PHONY: bootstrap-go
 bootstrap-go:

README.md

@@ -21,6 +21,7 @@ A CLI tool and Go library for generating a Software Bill of Materials (SBOM) fro
 
 ## Features
 - Catalog container images and filesystems to discover packages and libraries.
+- Generate in-toto attestations where an SBOM is included as the payload.
 - Supports packages and libraries from various ecosystems (APK, DEB, RPM, Ruby Bundles, Python Wheel/Egg/requirements.txt, JavaScript NPM/Yarn, Java JAR/EAR/WAR/PAR/SAR, Jenkins plugins JPI/HPI, Go modules, PHP Composer)
 - Linux distribution identification (supports Alpine, BusyBox, CentOS/RedHat, Debian/Ubuntu flavored distributions)
 - Supports Docker and OCI image formats
@@ -68,7 +69,8 @@ nix-shell -p syft
 
 ## Getting started
 
-To generate an SBOM for a Docker or OCI image:
+#### SBOM
+To generate an SBOM for an OCI image:
 ```
 syft <image>
 ```
@@ -85,6 +87,17 @@ To include software from all image layers in the SBOM, regardless of its presenc
 syft packages <image> --scope all-layers
 ```
 
+#### SBOM Attestation
+To generate an attested SBOM for an OCI image as the predicate of an in-toto attestation
+```
+syft attest --output [FORMAT] --key [KEY] [SOURCE] [flags]
+```
+
+The above output is in the form of the [DSSE envelope](https://github.com/secure-systems-lab/dsse/blob/master/envelope.md#dsse-envelope).
+The payload is a base64 encoded `in-toto` statement with the SBOM as the predicate, the payload type is `application/vnd.in-toto+json`, and the signatures array is populated
+with the contents needed for public key verification. For details on workflows using this command see [here](#adding-an-sbom-to-an-image-as-an-attestation-using-syft).
+
+
 ### Supported sources
 
 Syft can generate a SBOM from a variety of sources:
@@ -396,6 +409,16 @@ registry:
       token: ""
       # - ... # note, more credentials can be provided via config file only
 
+# generate an attested SBOM
+attest:
+  # path to the private key file to use for attestation
+  # SYFT_ATTEST_KEY env var
+  key: "cosign.key"
+
+  # password to decrypt to given private key
+  # SYFT_ATTEST_PASSWORD env var, additionally responds to COSIGN_PASSWORD
+  password: ""
+
 log:
   # use structured logging
   # same as SYFT_LOG_STRUCTURED env var
@@ -432,30 +455,32 @@ anchore:
   dockerfile: ""
 ```
 
-### Adding an SBOM to an image as an attestation
+### Adding an SBOM to an image as an attestation using Syft
+
+`syft attest --output [FORMAT] --key [KEY] [SOURCE] [flags]`
+
 SBOMs themselves can serve as input to different analysis tools. The Anchore organization offers the vulnerability scanner
 [grype](https://github.com/anchore/grype) as one such tool.
 One of the foundational approaches to "trust" between tools is for producers to use the artifacts generated by syft as attestations to their images.
-The SBOM output of syft can be used with the [cosign](https://github.com/sigstore/cosign) tool to generate an attestation that is attached to a signed image.
+The DSSE output of `syft attest` can be used with the [cosign](https://github.com/sigstore/cosign) tool to attach an attestation to an image.
 
 #### Example attest
-Note for the following example replace `test/image:latest` with an image you own. You should also have push access to 
+Note for the following example replace `docker.io/image:latest` with an image you own. You should also have push access to 
 its remote reference. Replace $MY_PRIVATE_KEY with a private key you own or have generated with cosign.
 
 ```bash
-cosign sign --key $MY_PRIVATE_KEY test/image:latest
-syft test/image:latest -o json > test_latest_sbom.json
-cosign attest --predicate test_latest_sbom.json --key $MY_PRIVATE_KEY test/image:latest
+syft attest --key $MY_PRIVATE_KEY docker.io/image:latest > image_latest_sbom_attestation.json
+cosign attach attestation --attestation image_latest_sbom_attestation.json docker.io/image:latest
 ```
 
 Verify the new attestation exists on your image
 ```bash
-cosign verify-attestation -key $MY_PUBLIC_KEY test/image:latest | jq '.payload |= @base64d | .payload | fromjson | .predicate.Data | fromjson | .'
+cosign verify-attestation -key $MY_PUBLIC_KEY docker.io/image:latest | jq '.payload | @base64d | .payload | fromjson | .predicate'
 ```
 
 You should see this output along with the attached SBOM.
 ```
-Verification for test/image:latest --
+Verification for docker.io/image:latest --
 The following checks were performed on each of these signatures:
   - The cosign claims were validated
   - The signatures were verified against the specified public key