Add keyderivation with pbkdf2 in swift

ios/Classes/KeyDerivation.swift

@@ -0,0 +1,40 @@
+//
+//  KeyDerivation.swift
+//
+//  NativeCryptoPlugin
+//
+//  Copyright (c) 2020
+//  Author: Hugo Pointcheval
+//
+
+import Foundation
+import CommonCrypto
+
+class KeyDerivation {
+    func pbkdf2(password: String, salt: String, keyLength: Int, iteration: Int, algorithm: HashAlgorithm) -> Data? {
+        
+        let passwordData = password.data(using: .utf8)!
+        let saltData = salt.data(using: .utf8)!
+        
+        var derivedKeyData = Data(repeating: 0, count: keyLength)
+        var localDerivedKeyData = derivedKeyData
+            
+        let derivationStatus = derivedKeyData.withUnsafeMutableBytes { derivedKeyBytes in
+            saltData.withUnsafeBytes { saltBytes in
+                CCKeyDerivationPBKDF(
+                    CCPBKDFAlgorithm(kCCPBKDF2),
+                    password, passwordData.count,
+                    saltBytes, saltData.count,
+                    algorithm.pbkdf2,
+                    UInt32(iteration),
+                    derivedKeyBytes, localDerivedKeyData.count)
+            }
+        }
+        if (derivationStatus != kCCSuccess) {
+            print("Error: \(derivationStatus)")
+            return nil;
+        }
+        
+        return derivedKeyData
+    }
+}