Encryption in iOS

EncryptionHelper.swift

//
//  EncryptionHelper.swift
//  Demo3
//
//

import Foundation
import CommonCrypto

struct AES {

    // MARK: - Value
    // MARK: Private
    private let key: Data
    private let iv: Data


    // MARK: - Initialzier
    init?(key: String, iv: String) {
        guard key.count == kCCKeySizeAES128 || key.count == kCCKeySizeAES256, let keyData = key.data(using: .utf8) else {
            debugPrint("Error: Failed to set a key.")
            return nil
        }

        guard iv.count == kCCBlockSizeAES128, let ivData = iv.data(using: .utf8) else {
            debugPrint("Error: Failed to set an initial vector.")
            return nil
        }


        self.key = keyData
        self.iv  = ivData
    }


    // MARK: - Function
    // MARK: Public
    func encrypt(string: String) -> Data? {
        return crypt(data: string.data(using: .utf8), option: CCOperation(kCCEncrypt))
    }

    func decrypt(data: Data?) -> String? {
        guard let decryptedData = crypt(data: data, option: CCOperation(kCCDecrypt)) else { return nil }
        return String(bytes: decryptedData, encoding: .utf8)
    }

    func crypt(data: Data?, option: CCOperation) -> Data? {
        guard let data = data else { return nil }

        let cryptLength = data.count + kCCBlockSizeAES128
        var cryptData   = Data(count: cryptLength)

        let keyLength = key.count
        let options   = CCOptions(kCCOptionPKCS7Padding)

        var bytesLength = Int(0)

        let status = cryptData.withUnsafeMutableBytes { cryptBytes in
            data.withUnsafeBytes { dataBytes in
                iv.withUnsafeBytes { ivBytes in
                    key.withUnsafeBytes { keyBytes in
                    CCCrypt(option, CCAlgorithm(kCCAlgorithmAES), options, keyBytes.baseAddress, keyLength, ivBytes.baseAddress, dataBytes.baseAddress, data.count, cryptBytes.baseAddress, cryptLength, &bytesLength)
                    }
                }
            }
        }

        guard UInt32(status) == UInt32(kCCSuccess) else {
            debugPrint("Error: Failed to crypt data. Status \(status)")
            return nil
        }

        cryptData.removeSubrange(bytesLength..<cryptData.count)
        return cryptData
    }
}

//Usage
   let message     = "Top Secret Key"
    let messageData = message.data(using:String.Encoding.utf8)!
    let keyData     = "demoKey".data(using:String.Encoding.utf8)!
    let ivData      = "demoIV".data(using:String.Encoding.utf8)!

    let aes256 = AES(key: "demoKey", iv: "DemoIV")

    let encryptedPassword256 = aes256?.encrypt(string: message)
    
    var encryptedStr1     = encryptedPassword256!.base64EncodedString()
    print("encryptedBase64-->", encryptedStr1)