如何在 swift 中使用带有 PKCS5PADDING 的 AES-256 CFB 解密字符串？

Question

我正在寻找使用 AES 解密字符串，我尝试了 SO 的多个解决方案，但没有一个有帮助，我无法获得解决方案。 android 开发人员使用Cipher执行以下代码：-

    private static final byte[] initVector = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    private static Cipher getAES_Cipher(int opmode) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
        InvalidAlgorithmParameterException {
    IvParameterSpec iv = new IvParameterSpec(initVector);
    SecretKeySpec skeySpec = new SecretKeySpec(Arrays.copyOfRange(getSHA(key), 0, 32), "AES");

    Cipher cipher = Cipher.getInstance("AES/CFB/PKCS5PADDING");
    cipher.init(opmode, skeySpec, iv);
    return cipher;
}

同样，我尝试使用CryptoSwift来执行此操作，下面是我用来执行此操作的代码：-

extension String {


func aesEncrypt(key: String, iv: String) throws -> String {

    let data: Array<UInt8> = (self.data(using: .utf8)?.bytes)!
    var key: Array<UInt8> = (key.data(using: .utf8)?.bytes)!
    let iv: Array<UInt8> = (iv.data(using: .utf8)?.bytes)!

    do {
        let encrypted = try AES(key: key, blockMode: CFB(iv: iv), padding: .pkcs5).encrypt(data)
        let encryptedData = Data(encrypted)
        let decrypted = try AES(key: key, blockMode: CFB(iv: iv), padding: .pkcs5).decrypt(encrypted)
        let decryptedData = Data(decrypted)
        let str = String.init(data: decryptedData, encoding: .utf8)
        print(str ?? String())
        return encryptedData.base64EncodedString()

    } catch {
        print(error)
        return "error"
    }
}

func aesDecrypt(key: String, iv: String) throws -> String {

    let data: Array<UInt8> = (Data(base64Encoded: self)?.bytes)!
    let key: Array<UInt8> = (key.data(using: .utf8)?.bytes)!
    let iv: Array<UInt8> = (iv.data(using: .utf8)?.bytes)!



    do {
        let decrypted = try AES(key: key.sha256(), blockMode: CFB(iv: iv), padding: .pkcs5).decrypt(data)
        let decryptedData = Data(decrypted)
        guard let value = String.init(data: decryptedData, encoding: .utf8) else {
            return "error"
        }
        return value

    } catch {
        print(error)
        return "error"
    }
}

}

在 ViewDidLoad() 我这样称呼它：-

    let message = "My Encrypted String From The Server"
    let test = try! message.aesDecrypt(key: "dfksjghlskjdfhglksjdfhglkjsdhfglkjhsfopweiurtypoweirutopiewrutgopiruegoijnsdeghsedrghesrerthigoererhehewthgewrhywertyweyweyewrtewrtyewihgoie", iv: "0000000000000000")

    print(test)

当我传递与 android 相同的iv时，我还想强调一件事，即“{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }"我从CryptoSwift库中收到错误为invalidInitializationVector但是当我通过 iv:"0000000000000000" 我收到一个错误 -->

  guard let value = String.init(data: decryptedData, encoding: .utf8) else {
        return "error"
    }

我相信这与我在那里经过的静脉注射有关。

伙计们任何帮助将不胜感激

谢谢你

Answer 1

尝试使用 CryptoSwift 解码某些数据时发现了这个问题。 尝试了代码，它也对我不起作用（确实返回“错误”）。

问题在于解密方法并且与密钥有关。

你有加密：

let encrypted = try AES(key: key, blockMode: CFB(iv: iv), padding: .pkcs5).encrypt(data)

但是要解密，代码如下所示：

let decrypted = try AES(key: key.sha256(), blockMode: CFB(iv: iv), padding: .pkcs5).decrypt(data)

对我来说，removing.sha256() 解决了这个问题。

所以最终的解密方法应该是：

func aesDecrypt(key: String, iv: String) throws -> String {

    let data: Array<UInt8> = (Data(base64Encoded: self)?.bytes)!
    let key: Array<UInt8> = (key.data(using: .utf8)?.bytes)!
    let iv: Array<UInt8> = (iv.data(using: .utf8)?.bytes)!

    do {
        let decrypted = try AES(key: key, blockMode: CFB(iv: iv), padding: .pkcs5).decrypt(data)
        let decryptedData = Data(decrypted)
        guard let value = String.init(data: decryptedData, encoding: .utf8) else {
            return "error"
        }
        return value
    } catch {
        print(error)
        return "error"
    }
}

也许它会帮助某人并节省一些时间。