1 files changed, 36 insertions, 0 deletions
diff --git a/whisper/util.go b/whisper/util.go
new file mode 100644
index 000000000..7a222395f
--- /dev/null
+++ b/whisper/util.go
@@ -0,0 +1,36 @@
+package whisper
+
+import "github.com/ethereum/go-ethereum/crypto"
+
+func hashTopic(topic []byte) []byte {
+	return crypto.Sha3(topic)[:4]
+}
+
+// NOTE this isn't DRY, but I don't want to iterate twice.
+
+// Returns a formatted topics byte slice.
+// data: unformatted data (e.g., no hashes needed)
+func Topics(data [][]byte) [][]byte {
+	d := make([][]byte, len(data))
+	for i, byts := range data {
+		d[i] = hashTopic(byts)
+	}
+	return d
+}
+
+func TopicsFromString(data ...string) [][]byte {
+	d := make([][]byte, len(data))
+	for i, str := range data {
+		d[i] = hashTopic([]byte(str))
+	}
+	return d
+}
+
+func bytesToMap(s [][]byte) map[string]struct{} {
+	m := make(map[string]struct{})
+	for _, topic := range s {
+		m[string(topic)] = struct{}{}
+	}
+
+	return m
+}