main: Add '-devrandom' commandline option

Allows to use /dev/random for generating the master key instead of the
default Go implementation. When the kernel random generator has been
properly initialized both are considered equally secure, however:

* Versions of Go prior to 1.9 just fall back to /dev/urandom if the
  getrandom() syscall would be blocking (Go Bug #19274)

* Kernel versions prior to 3.17 do not support getrandom(), and there
  is no check if the random generator has been properly initialized
  before reading from /dev/urandom

This is especially useful for embedded hardware with low-entroy. Please
note that generation of the master key might block indefinitely if the
kernel cannot harvest enough entropy.

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/cli/cli_test.go b/tests/cli/cli_test.go
index 97de8da..c7752f2 100644
--- a/tests/cli/cli_test.go
+++ b/tests/cli/cli_test.go
@@ -34,6 +34,11 @@ func TestInit(t *testing.T) {
 	}
 }
 
+// Test -init with -devrandom flag
+func TestInitDevRandom(t *testing.T) {
+	test_helpers.InitFS(t, "-devrandom")
+}
+
 // Test -init with -aessiv
 func TestInitAessiv(t *testing.T) {
 	dir := test_helpers.InitFS(t, "-aessiv")