Added DiffieHellman class

Pods

@@ -1 +1 @@
-Subproject commit 40bc969de75f70d546256db090dec25fe4661120
+Subproject commit d2cc7e97d653ab30ffadedd8034f6d8d27c27775

Signal/Signal-Info.plist

@@ -6,14 +6,10 @@
 	<dict>
 		<key>CarthageVersion</key>
 		<string>0.33.0</string>
-		<key>DateTime</key>
-		<string>Thu Jul 18 04:53:39 UTC 2019</string>
 		<key>OSXVersion</key>
-		<string>10.14.5</string>
+		<string>10.14.6</string>
 		<key>WebRTCCommit</key>
 		<string>1445d719bf05280270e9f77576f80f973fd847f8 M73</string>
-		<key>XCodeVersion</key>
-		<string>1000.1020</string>
 	</dict>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>en</string>

SignalServiceKit/src/Loki/Crypto/DiffieHellman.swift

@@ -0,0 +1,43 @@
+import CryptoSwift
+import Curve25519Kit
+
+public enum DiffieHellman {
+    // The length of the iv
+    public static let ivLength: Int32 = 16;
+    
+    public static func encrypt(plainText: Data, symmetricKey: Data) throws -> Data {
+        let iv = Randomness.generateRandomBytes(ivLength)!
+        let ivBytes = [UInt8](iv)
+        
+        let symmetricKeyBytes = [UInt8](symmetricKey)
+        let messageBytes = [UInt8](plainText)
+        
+        let blockMode = CBC(iv: ivBytes)
+        let aes = try AES(key: symmetricKeyBytes, blockMode: blockMode)
+        let cipherText = try aes.encrypt(messageBytes)
+        let ivAndCipher = ivBytes + cipherText
+        return Data(bytes: ivAndCipher, count: ivAndCipher.count)
+    }
+    
+    public static func encrypt(plainText: Data, publicKey: Data, privateKey: Data) throws -> Data {
+        let symmetricKey = try Curve25519.generateSharedSecret(fromPublicKey: publicKey, privateKey: privateKey)
+        return try encrypt(plainText: plainText, symmetricKey: symmetricKey)
+    }
+    
+    public static func decrypt(cipherText: Data, symmetricKey: Data) throws -> Data {
+        let symmetricKeyBytes = [UInt8](symmetricKey)
+        let ivBytes = [UInt8](cipherText[..<ivLength])
+        let cipherBytes = [UInt8](cipherText[ivLength...])
+        
+        let blockMode = CBC(iv: ivBytes)
+        let aes = try AES(key: symmetricKeyBytes, blockMode: blockMode)
+        let decrypted = try aes.decrypt(cipherBytes)
+        
+        return Data(bytes: decrypted, count: decrypted.count)
+    }
+    
+    public static func decrypt(cipherText: Data, publicKey: Data, privateKey: Data) throws -> Data {
+        let symmetricKey = try Curve25519.generateSharedSecret(fromPublicKey: publicKey, privateKey: privateKey)
+        return try decrypt(cipherText: cipherText, symmetricKey: symmetricKey)
+    }
+}