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Improved documentation for Crypto class.

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This commit is contained in:
Felix Ableitner 2015-10-18 22:36:22 +02:00
parent 269fe41ebf
commit a951b05965
2 changed files with 35 additions and 26 deletions
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59
core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala
View file

@ -14,32 +14,31 @@ import com.nutomic.ensichat.core.interfaces.{Log, Settings}
object Crypto {
/**
* Name of algorithm used for key generation.
* Algorithm used to generate the local public/private keypair.
*
* This keypair is generated on first start, and persistent for the lifetime of the app.
*/
val KeyAlgorithm = "RSA"
val PublicKeyAlgorithm = "RSA"
/**
* Number of bits for local key pair.
* Length of the local public/private keypair in bits.
*/
val KeySize = 4096
val PublicKeySize = 4096
/**
* Algorithm used for message signing.
*/
val SignAlgorithm = "SHA256withRSA"
val SigningAlgorithm = "SHA256withRSA"
/**
* Algorithm used for symmetric crypto cipher.
*/
val SymmetricCipherAlgorithm = "AES"
/**
* Algorithm used for symmetric message encryption.
* Algorithm used for the symmetric encryption key.
*
* A new key is generated for every message to be encrypted.
*/
val SymmetricKeyAlgorithm = "AES"
/**
* Length of the symmetric message encryption key in bits.
* Length of the symmetric encryption key in bits.
*/
val SymmetricKeyLength = 128
@ -48,10 +47,19 @@ object Crypto {
*/
val KeyHashAlgorithm = "SHA-256"
/**
* Name of the preference where the local address is stored.
*/
private val LocalAddressKey = "local_address"
/**
* Filename of the local private key in [[Crypto.keyFolder]].
*/
private val PrivateKeyAlias = "local-private"
/**
* Filename of the local public key in [[Crypto.keyFolder]].
*/
private val PublicKeyAlias = "local-public"
}
@ -66,7 +74,8 @@ class Crypto(settings: Settings, keyFolder: File) {
private val Tag = "Crypto"
/**
* Generates a new key pair using [[KeyAlgorithm]] with [[KeySize]] bits and stores the keys.
* Generates a new key pair using [[ [[Crypto.keyFolder]].]] with [[KeySize]] bits and stores the
* keys.
*
* Does nothing if the key pair already exists.
*/
@ -77,8 +86,8 @@ class Crypto(settings: Settings, keyFolder: File) {
var address: Address = null
var keyPair: KeyPair = null
do {
val keyGen = KeyPairGenerator.getInstance(KeyAlgorithm)
keyGen.initialize(KeySize)
val keyGen = KeyPairGenerator.getInstance(PublicKeyAlgorithm)
keyGen.initialize(PublicKeySize)
keyPair = keyGen.genKeyPair()
address = calculateAddress(keyPair.getPublic)
@ -122,7 +131,7 @@ class Crypto(settings: Settings, keyFolder: File) {
}
def sign(msg: Message): Message = {
val sig = Signature.getInstance(SignAlgorithm)
val sig = Signature.getInstance(SigningAlgorithm)
val key = loadKey(PrivateKeyAlias, classOf[PrivateKey])
sig.initSign(key)
sig.update(msg.body.write)
@ -133,7 +142,7 @@ class Crypto(settings: Settings, keyFolder: File) {
val publicKey =
if (key != null) key
else loadKey(msg.header.origin.toString, classOf[PublicKey])
val sig = Signature.getInstance(SignAlgorithm)
val sig = Signature.getInstance(SigningAlgorithm)
sig.initVerify(publicKey)
sig.update(msg.body.write)
sig.verify(msg.crypto.signature.get)
@ -203,7 +212,7 @@ class Crypto(settings: Settings, keyFolder: File) {
} finally {
fis.foreach(_.close())
}
val keyFactory = KeyFactory.getInstance(KeyAlgorithm)
val keyFactory = KeyFactory.getInstance(PublicKeyAlgorithm)
keyType match {
case c if c == classOf[PublicKey] =>
val keySpec = new X509EncodedKeySpec(data)
@ -219,7 +228,7 @@ class Crypto(settings: Settings, keyFolder: File) {
// Symmetric encryption of data
val secretKey = makeSecretKey()
val symmetricCipher = Cipher.getInstance(SymmetricCipherAlgorithm)
val symmetricCipher = Cipher.getInstance(SymmetricKeyAlgorithm)
symmetricCipher.init(Cipher.ENCRYPT_MODE, secretKey)
val encrypted = new EncryptedBody(copyThroughCipher(symmetricCipher, msg.body.write))
@ -227,7 +236,7 @@ class Crypto(settings: Settings, keyFolder: File) {
val publicKey =
if (key != null) key
else loadKey(msg.header.target.toString, classOf[PublicKey])
val asymmetricCipher = Cipher.getInstance(KeyAlgorithm)
val asymmetricCipher = Cipher.getInstance(PublicKeyAlgorithm)
asymmetricCipher.init(Cipher.WRAP_MODE, publicKey)
new Message(msg.header,
@ -236,12 +245,12 @@ class Crypto(settings: Settings, keyFolder: File) {
def decrypt(msg: Message): Message = {
// Asymmetric decryption of secret key
val asymmetricCipher = Cipher.getInstance(KeyAlgorithm)
val asymmetricCipher = Cipher.getInstance(PublicKeyAlgorithm)
asymmetricCipher.init(Cipher.UNWRAP_MODE, loadKey(PrivateKeyAlias, classOf[PrivateKey]))
val key = asymmetricCipher.unwrap(msg.crypto.key.get, SymmetricKeyAlgorithm, Cipher.SECRET_KEY)
// Symmetric decryption of data
val symmetricCipher = Cipher.getInstance(SymmetricCipherAlgorithm)
val symmetricCipher = Cipher.getInstance(SymmetricKeyAlgorithm)
symmetricCipher.init(Cipher.DECRYPT_MODE, key)
val decrypted = copyThroughCipher(symmetricCipher, msg.body.asInstanceOf[EncryptedBody].data)
val body = msg.header.asInstanceOf[ContentHeader].contentType match {
@ -265,7 +274,7 @@ class Crypto(settings: Settings, keyFolder: File) {
val baos = new ByteArrayOutputStream()
val cos = new CipherOutputStream(baos, cipher)
var i = 0
val b = new Array[Byte](1024)
val b = new Array[Byte](8192)
while({i = bais.read(b); i != -1}) {
cos.write(b, 0, i)
}
@ -277,14 +286,14 @@ class Crypto(settings: Settings, keyFolder: File) {
* Creates a new, random AES key.
*/
private def makeSecretKey(): SecretKey = {
val kgen = KeyGenerator.getInstance(SymmetricCipherAlgorithm)
val kgen = KeyGenerator.getInstance(SymmetricKeyAlgorithm)
kgen.init(SymmetricKeyLength)
val key = kgen.generateKey()
new SecretKeySpec(key.getEncoded, SymmetricKeyAlgorithm)
}
/**
* Hashes the given public key and returns the hash as address.
* Generates the address by hashing the given public key with [[KeyHashAlgorithm]].
*/
def calculateAddress(key: PublicKey): Address = {
val md = MessageDigest.getInstance(KeyHashAlgorithm)

2
core/src/main/scala/com/nutomic/ensichat/core/body/ConnectionInfo.scala
View file

@ -22,7 +22,7 @@ object ConnectionInfo {
val encoded = new Array[Byte](length)
b.get(encoded, 0, length)
val factory = KeyFactory.getInstance(Crypto.KeyAlgorithm)
val factory = KeyFactory.getInstance(Crypto.PublicKeyAlgorithm)
val key = factory.generatePublic(new X509EncodedKeySpec(encoded))
new ConnectionInfo(key)
}