update readme and stuff

CryptoSwift/ChaCha20.swift

@@ -8,7 +8,7 @@
 
 import Foundation
 
-internal class ChaCha20 {
+class ChaCha20 {
     private let stateSize = 16
     private let blockSize = 16 * 4
     private var context:Context = Context()
@@ -17,7 +17,7 @@ internal class ChaCha20 {
         var input:[UInt32] = [UInt32](count: 16, repeatedValue: 0)
     }
     
-    internal init(key:NSData, iv:NSData) {
+    init(key:NSData, iv:NSData) {
         context = keySetup(iv: iv, key: key)
     }
 
@@ -28,11 +28,15 @@ internal class ChaCha20 {
         }
     }
     
-    internal func encrypt(message:NSData) -> NSData {
+    func encrypt(message:NSData) -> NSData {
         let output = encryptBytes(message.arrayOfBytes())
         return NSData(bytes: output, length: output.count)
     }
     
+    func decrypt(message:NSData) -> NSData {
+        return encrypt(message)
+    }
+    
     private func wordToByte(input:[UInt32] /* 64 */) -> [Byte]? /* 16 */ {
         if (input.count != stateSize) {
             return nil;

CryptoSwift/Cipher.swift

@@ -18,4 +18,13 @@ public enum Cipher {
                 return chacha.encrypt(message)
         }
     }
+    
+    public func decrypt(message: NSData) -> NSData {
+        switch (self) {
+        case .ChaCha20(let key, let iv):
+            var chacha = CryptoSwift.ChaCha20(key: key, iv: iv);
+            return chacha.decrypt(message)
+        }
+    }
+
 }

CryptoSwiftTests/CipherTests.swift

@@ -53,8 +53,14 @@ class CipherTests: XCTestCase {
             let message = [Byte](count: (countElements(expectedHex) / 2), repeatedValue: 0)
             let messageData = NSData(bytes: message, length: message.count);
             
-            let ch = Cipher.ChaCha20(key: keyData, iv: ivData)
-            let encrypted = ch.encrypt(messageData)
+            let setup = (key: keyData, iv: ivData)
+            let encrypted = Cipher.ChaCha20(setup).encrypt(messageData)
+            let decrypted = Cipher.ChaCha20(setup).decrypt(encrypted)
+            XCTAssertEqual(messageData, decrypted, "ChaCha20 decryption failed");
+            
+            if (encrypted.isEqual(decrypted)) {
+                print("FAIL!")
+            }
             
             XCTAssertEqual(encrypted.hexString, expectedHex, "ChaCha20 failed");
         }

README.md

@@ -60,6 +60,22 @@ Hashing a String and printing result
         println(hash)
     }
     
+Working with Cipher
+
+	// convenience setup tuplet
+	let setup = (key: keyData, iv: ivData)
+	
+	// encrypt
+	let encrypted:NSData = Cipher.ChaCha20(setup).encrypt(dataToEncrypt)
+	
+	// decrypt
+	let decrypted:NSData = Cipher.ChaCha20(setup).decrypt(encrypted)
+	
+	// check
+	if (encrypted.isEqual(decrypted)) {
+		print("Decryption failed!")
+	}
+    
 ##Contact
 Marcin Krzyżanowski [@krzyzanowskim](http://twitter.com/krzyzanowskim)