init

internal/keymgr/password.go

@@ -0,0 +1,30 @@
+package keymgr
+
+import (
+	"crypto/rand"
+	"math/big"
+)
+
+// charset avoids visually ambiguous characters (0/O, 1/l/I) since this
+// password is normally read aloud or typed by hand on the recipient side.
+const passwordCharset = "23456789ABCDEFGHJKMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz"
+
+// GenerateBatchPassword returns a cryptographically random password shared
+// by every archive produced in one export batch. It is shown to the admin
+// exactly once (see the export result screen) and must be relayed to each
+// recipient over a channel separate from the archive itself.
+func GenerateBatchPassword(length int) (string, error) {
+	if length <= 0 {
+		length = 20
+	}
+	out := make([]byte, length)
+	max := big.NewInt(int64(len(passwordCharset)))
+	for i := range out {
+		n, err := rand.Int(rand.Reader, max)
+		if err != nil {
+			return "", err
+		}
+		out[i] = passwordCharset[n.Int64()]
+	}
+	return string(out), nil
+}