+hash salt derivation for any size. better naming

src/commonTest/kotlin/RingTest.kt

@@ -157,14 +157,14 @@ class RingTest {
         assertEquals(a, r1.findKey<SecretKey>(a.id))
         assertEquals(a, r1.keyByTag<UniversalKey>("foo_a"))
         assertEquals(b, r1.findKey<SigningKey>(b.id))
-        assertEquals(c, r1.keysById(c.id).first())
+        assertEquals(c, r1.findById(c.id).first())
 
         r1 = UniversalRing.join(listOf(ra, rb, rc, rd))
 
         assertEquals(a, r1.findKey<SecretKey>(a.id))
         assertEquals(a, r1.keyByTag<UniversalKey>("foo_a"))
         assertEquals(b, r1.findKey<SigningKey>(b.id))
-        assertEquals(c, r1.keysById(c.id).first())
+        assertEquals(c, r1.findById(c.id).first())
 
     }
 }