copy the other repo and make packages install.

commands.go

@@ -0,0 +1,26 @@
+package opentimestamps
+
+import (
+	"crypto/sha256"
+	"io"
+	"os"
+)
+
+func CreateDetachedTimestampForFile(
+	path string, cal *RemoteCalendar,
+) (*DetachedTimestamp, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	hasher := sha256.New()
+	if _, err := io.Copy(hasher, f); err != nil {
+		return nil, err
+	}
+	digest := hasher.Sum([]byte{})
+	ts, err := cal.Submit(digest)
+	if err != nil {
+		return nil, err
+	}
+	return NewDetachedTimestamp(*opSHA256, digest, ts)
+}