Support TOTP

app/src/main/java/com/chameth/yaotp/algos/Totp.kt

@@ -0,0 +1,11 @@
+package com.chameth.yaotp.algos
+
+import java.nio.ByteBuffer
+
+fun totp(key: ByteArray, startTime: Long = 0, step: Int = 30, currentTime: Long = currentTime(), length: Int = 6) = hotp(key, count(startTime, step, currentTime).toByteArray(), length)
+
+internal fun count(startTime: Long, step: Int, currentTime: Long) = (currentTime - startTime) / step
+
+internal fun currentTime() = System.currentTimeMillis() / 1000
+
+internal fun Long.toByteArray() = ByteBuffer.allocate(java.lang.Long.BYTES).putLong(this).array()

app/src/test/java/com/chameth/yaotp/algos/TotpTest.kt

@@ -0,0 +1,48 @@
+package com.chameth.yaotp.algos
+
+import com.natpryce.hamkrest.assertion.assert
+import com.natpryce.hamkrest.equalTo
+import org.junit.Test
+
+class TotpTest {
+
+    private val rfcKey = "12345678901234567890".toByteArray()
+
+    @Test
+    fun testCount_withDefaultStepAndStart_andPastValues() {
+        assert.that(count(0, 30, 59), equalTo(1L))
+        assert.that(count(0, 30, 1111111109), equalTo(37037036L))
+        assert.that(count(0, 30, 1234567890), equalTo(41152263L))
+    }
+
+    @Test
+    fun testCount_withDefaultStepAndStart_andFutureDates() {
+        assert.that(count(0, 30, 2000000000), equalTo(66666666L))
+        assert.that(count(0, 30, 20000000000), equalTo(666666666L))
+    }
+
+    @Test
+    fun testCount_withCustomStepAndStart() {
+        assert.that(count(2000000000, 30, 4000000000), equalTo(66666666L))
+        assert.that(count(0, 60, 4000000000), equalTo(66666666L))
+    }
+
+    @Test
+    fun testLongToByteArray_withRfcValues() {
+        assert.that(1L.toByteArray().toHexString(), equalTo("0000000000000001"))
+        assert.that(37037036L.toByteArray().toHexString(), equalTo("00000000023523ec"))
+        assert.that(41152263L.toByteArray().toHexString(), equalTo("000000000273ef07"))
+        assert.that(666666666L.toByteArray().toHexString(), equalTo("0000000027bc86aa"))
+    }
+
+    @Test
+    fun testTotp_withRfcValues_usingSha1() {
+        assert.that(totp(rfcKey, 0, 30, 59, 8), equalTo(94287082))
+        assert.that(totp(rfcKey, 0, 30, 1111111109, 8), equalTo(7081804))
+        assert.that(totp(rfcKey, 0, 30, 1111111111, 8), equalTo(14050471))
+        assert.that(totp(rfcKey, 0, 30, 1234567890, 8), equalTo(89005924))
+        assert.that(totp(rfcKey, 0, 30, 2000000000, 8), equalTo(69279037))
+        assert.that(totp(rfcKey, 0, 30, 20000000000, 8), equalTo(65353130))
+    }
+
+}