CryptoManager - encrypt / decrypt files for macOS using AES

CryptoManager

import Cocoa
import CommonCrypto


class CryptoManager {

    static var defaultCryptoKey: String? {
        set {
            if let key = newValue {
                StorageManager.save(cryptoKey: key)
            }
        }
        get {
            return StorageManager.read()
        }
    }

    func encryptFile(atPath filePath: String, withKey key: String, deleteSource: Bool) throws {
        let fileURL = URL(fileURLWithPath: filePath)
        let fileData = try Data(contentsOf: fileURL)

        guard let encryptedData = encrypt(data: fileData, key: key) else {
            throw NSError(domain: "EncryptionError", code: -1, userInfo: nil)
        }

        let encryptedFile = "\(filePath).psk"
        try encryptedData.write(to: URL(filePath: encryptedFile), options: .atomic)
        print("File encrypted successfully.")
        
        if deleteSource {
            deleteOriginalFile(atPath: filePath)
        }
    }

    func decryptFile(atPath filePath: String, withKey key: String, deleteSource: Bool) throws {
        let fileURL = URL(fileURLWithPath: filePath)
        let fileData = try Data(contentsOf: fileURL)

        guard let decryptedData = decrypt(data: fileData, key: key) else {
            throw NSError(domain: "DecryptionError", code: -1, userInfo: nil)
        }

        let decryptedFile = filePath.replacingOccurrences(of: ".psk", with: "")
        try decryptedData.write(to: URL(filePath: decryptedFile), options: .atomic)
        print("File decrypted successfully.")
        
        if deleteSource {
            deleteOriginalFile(atPath: filePath)
        }
    }

    private func deleteOriginalFile( atPath filePath: String ) {
        do {
            try FileManager.default.removeItem(atPath: filePath)
        } catch {
            print( error )
        }
    }
    
    // ---

    private func encrypt(data: Data, key: String) -> Data? {
        let keyData = key.data(using: .utf8)!
        let inputData = data as NSData
        let encryptedData = NSMutableData(length: Int(inputData.length) + kCCBlockSizeAES128)!
        let keyLength = size_t(kCCKeySizeAES128)

        let operation = CCOperation(kCCEncrypt)
        let algorithm = CCAlgorithm(kCCAlgorithmAES)
        let options = CCOptions(kCCOptionPKCS7Padding)

        var numBytesEncrypted: size_t = 0

        let cryptStatus = CCCrypt(
            operation,
            algorithm,
            options,
            (keyData as NSData).bytes, keyLength,
            nil,
            inputData.bytes, inputData.length,
            encryptedData.mutableBytes, encryptedData.length,
            &numBytesEncrypted
        )

        if cryptStatus == kCCSuccess {
            encryptedData.length = Int(numBytesEncrypted)
            return encryptedData as Data
        }

        return nil
    }

    private func decrypt(data: Data, key: String) -> Data? {
        let keyData = key.data(using: .utf8)!
        let inputData = data as NSData
        let decryptedData = NSMutableData(length: Int(inputData.length) + kCCBlockSizeAES128)!
        let keyLength = size_t(kCCKeySizeAES128)
        
        let operation = CCOperation(kCCDecrypt)
        let algorithm = CCAlgorithm(kCCAlgorithmAES)
        let options = CCOptions(kCCOptionPKCS7Padding)
        
        var numBytesDecrypted: size_t = 0
        
        let cryptStatus = CCCrypt(
            operation,
            algorithm,
            options,
            (keyData as NSData).bytes, keyLength,
            nil,
            inputData.bytes, inputData.length,
            decryptedData.mutableBytes, decryptedData.length,
            &numBytesDecrypted
        )
        
        if cryptStatus == kCCSuccess {
            decryptedData.length = Int(numBytesDecrypted)
            return decryptedData as Data
        }
        
        return nil
    }

}