Add added timestamp to Identities

src/main/java/org/asamk/signal/Hex.java

@@ -0,0 +1,22 @@
+package org.asamk.signal;
+
+public class Hex {
+
+    private final static char[] HEX_DIGITS = {
+            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+    };
+
+    public static String toStringCondensed(byte[] bytes) {
+        StringBuffer buf = new StringBuffer();
+        for (int i = 0; i < bytes.length; i++) {
+            appendHexChar(buf, bytes[i]);
+        }
+        return buf.toString();
+    }
+
+    private static void appendHexChar(StringBuffer buf, int b) {
+        buf.append(HEX_DIGITS[(b >> 4) & 0xf]);
+        buf.append(HEX_DIGITS[b & 0xf]);
+        buf.append(" ");
+    }
+}