Andrei Vereha
GitHub
commit
2892d385ab
4 changed files with 174 additions and 114 deletions
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@ -0,0 +1,128 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.pair
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import com.google.crypto.tink.subtle.X25519
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import info.nightscout.androidaps.logging.AAPSLogger
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import info.nightscout.androidaps.logging.AAPSLoggerTest
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import info.nightscout.androidaps.logging.LTag
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.BuildConfig
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions.MessageIOException
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import info.nightscout.androidaps.utils.extensions.toHex
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import org.spongycastle.crypto.engines.AESEngine
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import org.spongycastle.crypto.macs.CMac
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import org.spongycastle.crypto.params.KeyParameter
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import java.security.SecureRandom
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class KeyExchange(private val aapsLogger: AAPSLogger,
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var pdmPrivate: ByteArray = X25519.generatePrivateKey(),
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val pdmNonce: ByteArray = ByteArray(NONCE_SIZE)
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) {
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val pdmPublic = X25519.publicFromPrivate(pdmPrivate)
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var podPublic = ByteArray(PUBLIC_KEY_SIZE)
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var podNonce = ByteArray(NONCE_SIZE)
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val podConf = ByteArray(CMAC_SIZE)
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val pdmConf = ByteArray(CMAC_SIZE)
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var ltk = ByteArray(CMAC_SIZE)
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init {
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if (pdmNonce.all { it == 0.toByte() }) {
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// pdmNonce is in the constructor for tests
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val random = SecureRandom()
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random.nextBytes(pdmNonce)
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}
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}
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fun updatePodPublicData(payload: ByteArray) {
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if (payload.size != PUBLIC_KEY_SIZE + NONCE_SIZE) {
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throw MessageIOException("Invalid payload size")
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}
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podPublic = payload.copyOfRange(0, PUBLIC_KEY_SIZE)
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podNonce = payload.copyOfRange(PUBLIC_KEY_SIZE, PUBLIC_KEY_SIZE + NONCE_SIZE)
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generateKeys()
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}
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fun validatePodConf(payload: ByteArray) {
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if (!podConf.contentEquals(payload)) {
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aapsLogger.warn(
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LTag.PUMPBTCOMM,
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"Received invalid podConf. Expected: ${podConf.toHex()}. Got: ${payload.toHex()}"
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)
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throw MessageIOException("Invalid podConf value received")
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}
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}
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private fun generateKeys() {
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val curveLTK = X25519.computeSharedSecret(pdmPrivate, podPublic)
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val firstKey = podPublic.copyOfRange(podPublic.size - 4, podPublic.size) +
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pdmPublic.copyOfRange(pdmPublic.size - 4, pdmPublic.size) +
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podNonce.copyOfRange(podNonce.size - 4, podNonce.size) +
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pdmNonce.copyOfRange(pdmNonce.size - 4, pdmNonce.size)
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aapsLogger.debug(LTag.PUMPBTCOMM, "First key for LTK: ${firstKey.toHex()}")
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val intermediateKey = ByteArray(CMAC_SIZE)
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aesCmac(firstKey, curveLTK, intermediateKey)
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val ltkData = byteArrayOf(2.toByte()) +
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INTERMEDIARY_KEY_MAGIC_STRING +
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podNonce +
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pdmNonce +
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byteArrayOf(0.toByte(), 1.toByte())
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aesCmac(intermediateKey, ltkData, ltk)
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val confData = byteArrayOf(1.toByte()) +
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INTERMEDIARY_KEY_MAGIC_STRING +
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podNonce +
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pdmNonce +
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byteArrayOf(0.toByte(), 1.toByte())
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val confKey = ByteArray(CMAC_SIZE)
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aesCmac(intermediateKey, confData, confKey)
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val pdmConfData = PDM_CONF_MAGIC_PREFIX +
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pdmNonce +
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podNonce
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aesCmac(confKey, pdmConfData, pdmConf)
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmConf: ${pdmConf.toHex()}")
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val podConfData = POD_CONF_MAGIC_PREFIX +
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podNonce +
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pdmNonce
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aesCmac(confKey, podConfData, podConf)
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aapsLogger.debug(LTag.PUMPBTCOMM, "podConf: ${podConf.toHex()}")
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if (BuildConfig.DEBUG) {
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmPrivate: ${pdmPrivate.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmPublic: ${pdmPublic.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "podPublic: ${podPublic.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmNonce: ${pdmNonce.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "podNonce: ${podNonce.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK, donna key: ${curveLTK.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "Intermediate key: ${intermediateKey.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK: ${ltk.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "Conf KEY: ${confKey.toHex()}")
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}
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}
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companion object {
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private const val PUBLIC_KEY_SIZE = 32
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private const val NONCE_SIZE = 16
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const val CMAC_SIZE = 16
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private val INTERMEDIARY_KEY_MAGIC_STRING = "TWIt".toByteArray()
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private val PDM_CONF_MAGIC_PREFIX = "KC_2_U".toByteArray()
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private val POD_CONF_MAGIC_PREFIX = "KC_2_V".toByteArray()
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}
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}
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private fun aesCmac(key: ByteArray, data: ByteArray, result: ByteArray) {
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val aesEngine = AESEngine()
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val mac = CMac(aesEngine)
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mac.init(KeyParameter(key))
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mac.update(data, 0, data.size)
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mac.doFinal(result, 0)
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}
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@ -1,9 +1,7 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.pair
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import com.google.crypto.tink.subtle.X25519
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import info.nightscout.androidaps.logging.AAPSLogger
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import info.nightscout.androidaps.logging.LTag
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.BuildConfig
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.Id
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.exceptions.MessageIOException
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.MessageIO
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@ -12,27 +10,17 @@ import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.
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import info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.message.StringLengthPrefixEncoding.Companion.parseKeys
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import info.nightscout.androidaps.utils.extensions.hexStringToByteArray
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import info.nightscout.androidaps.utils.extensions.toHex
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import org.spongycastle.crypto.engines.AESEngine
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import org.spongycastle.crypto.macs.CMac
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import org.spongycastle.crypto.params.KeyParameter
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import java.security.SecureRandom
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internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgIO: MessageIO, val myId: Id, val podId: Id, val podAddress: Id) {
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internal class LTKExchanger(
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private val aapsLogger: AAPSLogger,
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private val msgIO: MessageIO,
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val myId: Id,
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val podId: Id,
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val podAddress: Id
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) {
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private val pdmPrivate = X25519.generatePrivateKey()
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private val pdmPublic = X25519.publicFromPrivate(pdmPrivate)
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private var podPublic = ByteArray(PUBLIC_KEY_SIZE)
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private var podNonce = ByteArray(NONCE_SIZE)
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private val pdmNonce = ByteArray(NONCE_SIZE)
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private val pdmConf = ByteArray(CMAC_SIZE)
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private val podConf = ByteArray(CMAC_SIZE)
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private val keyExchange = KeyExchange(aapsLogger)
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private var seq: Byte = 1
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private var ltk = ByteArray(CMAC_SIZE)
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init {
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val random = SecureRandom()
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random.nextBytes(pdmNonce)
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}
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fun negotiateLTK(): PairResult {
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// send SP1, SP2
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@ -48,7 +36,7 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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val podSps1 = msgIO.receiveMessage()
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processSps1FromPod(podSps1)
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// now we have all the data to generate: confPod, confPdm, ltk and noncePrefix
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generateKeys()
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seq++
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// send SPS2
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val sps2 = sps2()
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@ -66,13 +54,13 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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// TODO: failing to read or validate p0 will lead to undefined state
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// It could be that:
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// - the pod answered with p0 and we did not receive/could not process the answer
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// - the pod answered with some sort of error
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// - the pod answered with some sort of error. This is very unlikely, because we already received(and validated) SPS2 from the pod
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// But if sps2 conf value is incorrect, then we would probablysee this when receiving the pod podSps2(to test)
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val p0 = msgIO.receiveMessage()
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validateP0(p0)
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return PairResult(
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ltk = ltk,
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ltk = keyExchange.ltk,
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msgSeq = seq
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)
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}
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@ -93,7 +81,7 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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private fun sps1(): PairMessage {
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val payload = StringLengthPrefixEncoding.formatKeys(
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arrayOf("SPS1="),
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arrayOf(pdmPublic + pdmNonce)
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arrayOf(keyExchange.pdmPublic + keyExchange.pdmNonce)
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)
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return PairMessage(
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sequenceNumber = seq,
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@ -107,17 +95,13 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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aapsLogger.debug(LTag.PUMPBTCOMM, "Received SPS1 from pod: ${msg.payload.toHex()}")
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val payload = parseKeys(arrayOf(SPS1), msg.payload)[0]
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if (payload.size != 48) {
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throw MessageIOException("Invalid payload size")
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}
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podPublic = payload.copyOfRange(0, PUBLIC_KEY_SIZE)
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podNonce = payload.copyOfRange(PUBLIC_KEY_SIZE, PUBLIC_KEY_SIZE + NONCE_SIZE)
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keyExchange.updatePodPublicData(payload)
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}
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private fun sps2(): PairMessage {
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val payload = StringLengthPrefixEncoding.formatKeys(
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arrayOf(SPS2),
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arrayOf(pdmConf)
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arrayOf(keyExchange.pdmConf)
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)
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return PairMessage(
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sequenceNumber = seq,
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@ -133,16 +117,10 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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val payload = parseKeys(arrayOf(SPS2), msg.payload)[0]
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aapsLogger.debug(LTag.PUMPBTCOMM, "SPS2 payload from pod: ${payload.toHex()}")
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if (payload.size != CMAC_SIZE) {
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if (payload.size != KeyExchange.CMAC_SIZE) {
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throw MessageIOException("Invalid payload size")
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}
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if (!podConf.contentEquals(payload)) {
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aapsLogger.warn(
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LTag.PUMPBTCOMM,
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"Received invalid podConf. Expected: ${podConf.toHex()}. Got: ${payload.toHex()}"
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)
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throw MessageIOException("Invalid podConf value received")
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}
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keyExchange.validatePodConf(payload)
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}
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private fun sp2(): ByteArray {
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@ -171,74 +149,10 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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}
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}
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fun generateKeys() {
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val curveLTK = X25519.computeSharedSecret(pdmPrivate, podPublic)
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val firstKey = podPublic.copyOfRange(podPublic.size - 4, podPublic.size) +
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pdmPublic.copyOfRange(pdmPublic.size - 4, pdmPublic.size) +
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podNonce.copyOfRange(podNonce.size - 4, podNonce.size) +
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pdmNonce.copyOfRange(pdmNonce.size - 4, pdmNonce.size)
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aapsLogger.debug(LTag.PUMPBTCOMM, "First key for LTK: ${firstKey.toHex()}")
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val intermediateKey = ByteArray(CMAC_SIZE)
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aesCmac(firstKey, curveLTK, intermediateKey)
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val ltkData = byteArrayOf(2.toByte()) +
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INTERMEDIAR_KEY_MAGIC_STRING +
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podNonce +
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pdmNonce +
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byteArrayOf(0.toByte(), 1.toByte())
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aesCmac(intermediateKey, ltkData, ltk)
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val confData = byteArrayOf(1.toByte()) +
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INTERMEDIAR_KEY_MAGIC_STRING +
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podNonce +
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pdmNonce +
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byteArrayOf(0.toByte(), 1.toByte())
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val confKey = ByteArray(CMAC_SIZE)
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aesCmac(intermediateKey, confData, confKey)
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val pdmConfData = PDM_CONF_MAGIC_PREFIX +
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pdmNonce +
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podNonce
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aesCmac(confKey, pdmConfData, pdmConf)
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmConf: ${pdmConf.toHex()}")
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val podConfData = POD_CONF_MAGIC_PREFIX +
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podNonce +
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pdmNonce
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aesCmac(confKey, podConfData, podConf)
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aapsLogger.debug(LTag.PUMPBTCOMM, "podConf: ${podConf.toHex()}")
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if (BuildConfig.DEBUG) {
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmPrivate: ${pdmPrivate.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmPublic: ${pdmPublic.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "podPublic: ${podPublic.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "pdmNonce: ${pdmNonce.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "podNonce: ${podNonce.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK, donna key: ${curveLTK.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "Intermediate key: ${intermediateKey.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "LTK: ${ltk.toHex()}")
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aapsLogger.debug(LTag.PUMPBTCOMM, "Conf KEY: ${confKey.toHex()}")
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}
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}
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companion object {
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private const val PUBLIC_KEY_SIZE = 32
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private const val NONCE_SIZE = 16
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private const val CONF_SIZE = 16
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private const val CMAC_SIZE = 16
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private val INTERMEDIAR_KEY_MAGIC_STRING = "TWIt".toByteArray()
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private val PDM_CONF_MAGIC_PREFIX = "KC_2_U".toByteArray()
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private val POD_CONF_MAGIC_PREFIX = "KC_2_V".toByteArray()
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private const val GET_POD_STATUS_HEX_COMMAND = "ffc32dbd08030e0100008a"
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// TODO for now we are assuming this command is build out of constant parameters,
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// use a proper command builder for that.
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private const val GET_POD_STATUS_HEX_COMMAND =
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"ffc32dbd08030e0100008a" // TODO for now we are assuming this command is build out of constant parameters, use a proper command builder for that.
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private const val SP1 = "SP1="
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private const val SP2 = ",SP2="
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@ -249,11 +163,3 @@ internal class LTKExchanger(private val aapsLogger: AAPSLogger, private val msgI
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private val UNKNOWN_P0_PAYLOAD = byteArrayOf(0xa5.toByte())
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}
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}
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private fun aesCmac(key: ByteArray, data: ByteArray, result: ByteArray) {
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val aesEngine = AESEngine()
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val mac = CMac(aesEngine)
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mac.init(KeyParameter(key))
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mac.update(data, 0, data.size)
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mac.doFinal(result, 0)
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}
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@ -14,8 +14,8 @@ import java.security.SecureRandom
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class SessionEstablisher(
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private val aapsLogger: AAPSLogger,
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private val msgIO: MessageIO,
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private val ltk: ByteArray,
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private val eapSqn: ByteArray,
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ltk: ByteArray,
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eapSqn: ByteArray,
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private val myId: Id,
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private val podId: Id,
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private var msgSeq: Byte
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@ -0,0 +1,26 @@
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package info.nightscout.androidaps.plugins.pump.omnipod.dash.driver.comm.pair
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import info.nightscout.androidaps.logging.AAPSLoggerTest
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import info.nightscout.androidaps.utils.extensions.toHex
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import org.junit.Assert
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import org.junit.Assert.*
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import org.junit.Test
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import org.spongycastle.util.encoders.Hex
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class KeyExchangeTest {
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@Test fun testLTK() {
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val aapsLogger = AAPSLoggerTest()
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val ke = KeyExchange(
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aapsLogger,
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pdmPrivate= Hex.decode("27ec94b71a201c5e92698d668806ae5ba00594c307cf5566e60c1fc53a6f6bb6"),
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pdmNonce= Hex.decode("edfdacb242c7f4e1d2bc4d93ca3c5706")
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)
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val podPublicKey = Hex.decode("2fe57da347cd62431528daac5fbb290730fff684afc4cfc2ed90995f58cb3b74")
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val podNonce = Hex.decode("00000000000000000000000000000000")
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ke.updatePodPublicData(podPublicKey+podNonce)
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assertEquals(ke.pdmPublic.toHex(), "f2b6940243aba536a66e19fb9a39e37f1e76a1cd50ab59b3e05313b4fc93975e")
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assertEquals(ke.pdmConf.toHex(), "5fc3b4da865e838ceaf1e9e8bb85d1ac")
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ke.validatePodConf(Hex.decode("af4f10db5f96e5d9cd6cfc1f54f4a92f"))
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assertEquals(ke.ltk.toHex(), "341e16d13f1cbf73b19d1c2964fee02b")
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}
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}
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