api: Add go files

I know this is a huge commit, but I can't be bothered to check
this in part by part.

api/utils_crypto_test.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestRandomHexBasics(t *testing.T) {
+	hex1, err := randomHex(32)
+	if err != nil {
+		t.Errorf("unexpected error creating hex: %v", err)
+		return
+	}
+
+	if hex1 == "" {
+		t.Errorf("randomly generated hex empty")
+		return
+	}
+
+	hex2, err := randomHex(32)
+	if err != nil {
+		t.Errorf("unexpected error creating hex: %v", err)
+		return
+	}
+
+	if hex1 == hex2 {
+		t.Errorf("two randomly generated hexes found to be the same: '%s'", hex1)
+		return
+	}
+}