chore: establish local platform baseline

cmd/firmware-sign/main.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"os"
+)
+
+type signedFirmware struct {
+	PublicKeyBase64 string `json:"public_key_base64"`
+	SignatureBase64 string `json:"signature_base64"`
+	SHA256          string `json:"sha256"`
+	Size            int    `json:"size"`
+	Manifest        string `json:"manifest"`
+}
+
+func main() {
+	if len(os.Args) != 5 {
+		fmt.Fprintln(os.Stderr, "usage: firmware-sign <model> <hardware-revision> <version> <file>")
+		os.Exit(2)
+	}
+	content, err := os.ReadFile(os.Args[4])
+	if err != nil {
+		panic(err)
+	}
+	result, err := signFirmware(os.Args[1], os.Args[2], os.Args[3], content)
+	if err != nil {
+		panic(err)
+	}
+	if err := json.NewEncoder(os.Stdout).Encode(result); err != nil {
+		panic(err)
+	}
+}
+
+func signFirmware(model, hardwareRevision, version string, content []byte) (signedFirmware, error) {
+	publicKey, privateKey, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		return signedFirmware{}, err
+	}
+	digest := sha256.Sum256(content)
+	digestText := hex.EncodeToString(digest[:])
+	manifest := fmt.Sprintf("firmware-manifest-v1\nmodel=%s\nhardware_revision=%s\nversion=%s\nsha256=%s\nsize=%d\n", model, hardwareRevision, version, digestText, len(content))
+	return signedFirmware{
+		PublicKeyBase64: base64.StdEncoding.EncodeToString(publicKey),
+		SignatureBase64: base64.StdEncoding.EncodeToString(ed25519.Sign(privateKey, []byte(manifest))),
+		SHA256:          digestText, Size: len(content), Manifest: manifest,
+	}, nil
+}