CryptoKit ChaChaPoly Helper Functions

CryptoKitHelpers.swift

import UIKit
import CryptoKit

struct CryptoKitHelpers {
    static func encrypt(secret: String, image: UIImage, compressionRatio: CGFloat = 0.9) throws -> Data? {
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        guard let contentData = UIImageToDataJPEG2(image: image, compressionRatio: compressionRatio) else {
            return nil
        }
        return try ChaChaPoly.seal(contentData, using: encryptionKey).combined
    }
    
    static func encrypt(secret: String, contentData: Data) throws -> Data? {
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        return try ChaChaPoly.seal(contentData, using: encryptionKey).combined
    }

    static func encryptFromFile(secret: String, url: URL) throws -> Data? {
        guard fileExists(url) else {
            return nil
        }
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        let contentData = try Data.init(contentsOf: url, options: .mappedIfSafe)
        return try ChaChaPoly.seal(contentData, using: encryptionKey).combined
    }

    static func encryptSaveToFile(secret: String, contentData: Data, url: URL) throws {
        guard let encryptionKey = getKey(secret: secret) else { return }
        let encryptedData = try ChaChaPoly.seal(contentData, using: encryptionKey).combined
        try encryptedData.write(to: url)
    }

    static func decryptFromFile(secret: String, url: URL) throws -> Data? {
        guard fileExists(url) else {
            return nil
        }
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        let encryptedContent = try Data.init(contentsOf: url, options: .mappedIfSafe)
        let sealedBox = try ChaChaPoly.SealedBox(combined: encryptedContent)
        return try ChaChaPoly.open(sealedBox, using: encryptionKey)
    }

    static func decryptFromFile(secret: String, url: URL) throws -> UIImage? {
        guard fileExists(url) else {
            return nil
        }
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        let encryptedContent = try Data.init(contentsOf: url, options: .mappedIfSafe)
        let sealedBox = try ChaChaPoly.SealedBox(combined: encryptedContent)
        let data = try ChaChaPoly.open(sealedBox, using: encryptionKey)
        return UIImage(data: data)
    }
    
    static func decrypt(secret: String, encryptedContent: Data) throws -> Data? {
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        let sealedBox = try ChaChaPoly.SealedBox(combined: encryptedContent)
        return try ChaChaPoly.open(sealedBox, using: encryptionKey)
    }

    static func decrypt(secret: String, encryptedContent: Data) throws -> UIImage? {
        guard let encryptionKey = getKey(secret: secret) else { return nil }
        let sealedBox = try ChaChaPoly.SealedBox(combined: encryptedContent)
        let data = try ChaChaPoly.open(sealedBox, using: encryptionKey)
        return UIImage(data: data)
    }
    
    private static func getKey(secret: String) -> SymmetricKey? {
        guard let passwordData: Data = secret.data(using: .utf8) else {
            return nil
        }
        return SymmetricKey(data: SHA256.hash(data: passwordData))
    }
    
    private static func fileExists(_ url: URL) -> Bool {
        return FileManager.default.fileExists(atPath: url.path)
    }
    
    private static func UIImageToDataJPEG2(image: UIImage, compressionRatio: CGFloat = 0.9) -> Data? {
        return autoreleasepool(invoking: { () -> Data? in
            return image.jpegData(compressionQuality: compressionRatio)
        })
    }
}