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Use encrypt-then-mac instead of mac-and-encrypt.

This commit is contained in:
Felix Ableitner 2015-11-18 19:40:11 +01:00
parent 9b5175114f
commit 925eb2d5c5
4 changed files with 35 additions and 32 deletions
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10
core/src/main/scala/com/nutomic/ensichat/core/ConnectionHandler.scala
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@ -63,7 +63,7 @@ class ConnectionHandler(settings: Settings, database: DatabaseInterface,
settings.put("message_id", messageId + 1)
val msg = new Message(header, body)
val encrypted = crypto.encrypt(crypto.sign(msg))
val encrypted = crypto.encryptAndSign(msg)
router.onReceive(encrypted)
onNewMessage(msg)
}
@ -77,12 +77,12 @@ class ConnectionHandler(settings: Settings, database: DatabaseInterface,
*/
def onMessageReceived(msg: Message): Unit = {
if (msg.header.target == crypto.localAddress) {
val decrypted = crypto.decrypt(msg)
if (!crypto.verify(decrypted)) {
crypto.verifyAndDecrypt(msg) match {
case Some(msg) => onNewMessage(msg)
case None =>
Log.i(Tag, "Ignoring message with invalid signature from " + msg.header.origin)
return
}
onNewMessage(decrypted)
} else {
router.onReceive(msg)
}
@ -131,7 +131,7 @@ class ConnectionHandler(settings: Settings, database: DatabaseInterface,
return false
}
if (crypto.havePublicKey(sender) && !crypto.verify(msg, crypto.getPublicKey(sender))) {
if (crypto.havePublicKey(sender) && !crypto.verify(msg, Option(crypto.getPublicKey(sender)))) {
Log.i(Tag, "Ignoring ConnectionInfo message with invalid signature")
return false
}

33
core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala
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@ -135,15 +135,13 @@ class Crypto(settings: Settings, keyFolder: File) {
val key = loadKey(PrivateKeyAlias, classOf[PrivateKey])
sig.initSign(key)
sig.update(msg.body.write)
new Message(msg.header, new CryptoData(Option(sig.sign), None), msg.body)
new Message(msg.header, new CryptoData(Option(sig.sign), msg.crypto.key), msg.body)
}
def verify(msg: Message, key: PublicKey = null): Boolean = {
val publicKey =
if (key != null) key
else loadKey(msg.header.origin.toString, classOf[PublicKey])
def verify(msg: Message, key: Option[PublicKey] = None): Boolean = {
val sig = Signature.getInstance(SigningAlgorithm)
sig.initVerify(publicKey)
lazy val defaultKey = loadKey(msg.header.origin.toString, classOf[PublicKey])
sig.initVerify(key.getOrElse(defaultKey))
sig.update(msg.body.write)
sig.verify(msg.crypto.signature.get)
}
@ -223,9 +221,18 @@ class Crypto(settings: Settings, keyFolder: File) {
}
}
def encrypt(msg: Message, key: PublicKey = null): Message = {
assert(msg.crypto.signature.isDefined, "Message must be signed before encryption")
def encryptAndSign(msg: Message, key: Option[PublicKey] = None): Message = {
sign(encrypt(msg, key))
}
def verifyAndDecrypt(msg: Message, key: Option[PublicKey] = None): Option[Message] = {
if (verify(msg, key))
Option(decrypt(msg))
else
None
}
private def encrypt(msg: Message, key: Option[PublicKey] = None): Message = {
// Symmetric encryption of data
val secretKey = makeSecretKey()
val symmetricCipher = Cipher.getInstance(SymmetricKeyAlgorithm)
@ -233,17 +240,15 @@ class Crypto(settings: Settings, keyFolder: File) {
val encrypted = new EncryptedBody(copyThroughCipher(symmetricCipher, msg.body.write))
// Asymmetric encryption of secret key
val publicKey =
if (key != null) key
else loadKey(msg.header.target.toString, classOf[PublicKey])
val asymmetricCipher = Cipher.getInstance(PublicKeyAlgorithm)
asymmetricCipher.init(Cipher.WRAP_MODE, publicKey)
lazy val defaultKey = loadKey(msg.header.target.toString, classOf[PublicKey])
asymmetricCipher.init(Cipher.WRAP_MODE, key.getOrElse(defaultKey))
new Message(msg.header,
new CryptoData(msg.crypto.signature, Option(asymmetricCipher.wrap(secretKey))), encrypted)
new CryptoData(None, Option(asymmetricCipher.wrap(secretKey))), encrypted)
}
def decrypt(msg: Message): Message = {
private def decrypt(msg: Message): Message = {
// Asymmetric decryption of secret key
val asymmetricCipher = Cipher.getInstance(PublicKeyAlgorithm)
asymmetricCipher.init(Cipher.UNWRAP_MODE, loadKey(PrivateKeyAlias, classOf[PrivateKey]))

8
core/src/test/scala/com/nutomic/ensichat/core/CryptoTest.scala
View File

@ -32,7 +32,7 @@ class CryptoTest extends TestCase {
def testSignVerify(): Unit = {
MessageTest.messages.foreach { m =>
val signed = crypto.sign(m)
assertTrue(crypto.verify(signed, crypto.getLocalPublicKey))
assertTrue(crypto.verify(signed, Option(crypto.getLocalPublicKey)))
assertEquals(m.header, signed.header)
assertEquals(m.body, signed.body)
}
@ -40,9 +40,9 @@ class CryptoTest extends TestCase {
def testEncryptDecrypt(): Unit = {
MessageTest.messages.foreach{ m =>
val encrypted = crypto.encrypt(crypto.sign(m), crypto.getLocalPublicKey)
val decrypted = crypto.decrypt(encrypted)
assertEquals(m.body, decrypted.body)
val encrypted = crypto.encryptAndSign(m, Option(crypto.getLocalPublicKey))
val decrypted = crypto.verifyAndDecrypt(encrypted, Option(crypto.getLocalPublicKey))
assertEquals(m.body, decrypted.get.body)
assertEquals(m.header, encrypted.header)
}
}

12
core/src/test/scala/com/nutomic/ensichat/core/MessageTest.scala
View File

@ -48,21 +48,19 @@ class MessageTest extends TestCase {
val read = Message.read(new ByteArrayInputStream(bytes))
assertEquals(signed, read)
assertTrue(crypto.verify(read, crypto.getLocalPublicKey))
assertTrue(crypto.verify(read, Option(crypto.getLocalPublicKey)))
}
def testSerializeEncrypted(): Unit = {
MessageTest.messages.foreach{ m =>
val signed = crypto.sign(m)
val encrypted = crypto.encrypt(signed, crypto.getLocalPublicKey)
val encrypted = crypto.encryptAndSign(m, Option(crypto.getLocalPublicKey))
val bytes = encrypted.write
val read = Message.read(new ByteArrayInputStream(bytes))
assertEquals(encrypted.crypto, read.crypto)
val decrypted = crypto.decrypt(read)
assertEquals(m.header, decrypted.header)
assertEquals(m.body, decrypted.body)
assertTrue(crypto.verify(decrypted, crypto.getLocalPublicKey))
val decrypted = crypto.verifyAndDecrypt(read, Option(crypto.getLocalPublicKey))
assertEquals(m.header, decrypted.get.header)
assertEquals(m.body, decrypted.get.body)
}
}