解密AES/GCM/PKCS5Padding iOS Swift

Question

我正在尝试使用 AES 解密来解密 Base64Encoded String 消息。

加密消息（Base64Encoded 字符串）： tNC6umcfBS/gelbo2VJF3i4LAhUKMp4oDHWN5KyYUTWeJIQKKYx6oAcQnGncIrPJNC1tUYMKV4kJQj3q9voIOrxc1n7FmRFvDXeRgWGNcGYO66dH3VjoEgF0oxZOpfzwSZKSv3Jm7Q=

密码（字符串） =“SOMEPASSWORDSTRING”

解密消息的步骤：

1. 数据必须从 base 64 解码为普通字符串。

2. 从输入中提取 IV 和加密文本

3. 使用 IV 和相同的密码生成用于加密文本的密钥。 密钥生成应遵循与以下相同的步骤。

4. 生成 PBE 密钥（256 位）

    a. Specs created with passphrase and IV as salt, 62233 as iteration count b. Used PBKDF2WithHmacSHA256 to generate a secret factory because it's appropriate for turning passwords into keys. c. This key is further encoded and converted to another key with AES encryption.

5. 使用生成的密钥和 IV，以与以下完全相同的方式初始化密码

6. 此密钥初始化密码 object

    a. Used AES in GCM, GCM specs are prepared using tag size of 128 bits and the IV b. Cipher object is initialized using AES/GCM/PKCS5Padding. c. Based on operational mode the cipher is initialized with op mode(encryption), secret key and GCM params.

7. 生成密码以从加密文本中获取消息。

下面是用于解密输入消息的 JAVA 代码

public class Decryption {
    private static final String KEY_GENERATING_ALGO = "PBKDF2WithHmacSHA256";
      private static final String ENCRYPTION = "AES";
      private static final String TRANSFORMATION_ALGORITHM= "AES/GCM/PKCS5Padding";
       
      private static final int KEY_SIZE_BITS = 256;
      private static final int TAG_SIZE_BITS = 128;
      private static final int ITERATION_COUNT  = 62233;
      
    // Use following sample data to test the decryption-
//tNC6umcfBS/gelbo2VJF3i4LAhUKMp4oDHWN5KyYUTWeJIQKKYx6oAcQnGncIrPJNC1tUYMKV4kJQj3q9voIOrxc1n7FmRFvDXeRgWGNcGYO66dH3VjoEgF0oxZOpfzwSZKSv3Jm7Q==
      
      // This key has is base 64 encoded with IV prepended with encrypted text
      public Cipher initCipher(int encryptMode, String password, byte[] iv) throws InvalidKeySpecException {
            try {
                GCMParameterSpec gcmparams = new GCMParameterSpec(TAG_SIZE_BITS, iv);
                PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), iv, ITERATION_COUNT, KEY_SIZE_BITS);
                SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_GENERATING_ALGO);
                SecretKey pbeKey = factory.generateSecret(pbeKeySpec);
                byte[] keyBytes = pbeKey.getEncoded();
                SecretKey key = new SecretKeySpec(keyBytes, ENCRYPTION);
                Cipher cipher = Cipher.getInstance(TRANSFORMATION_ALGORITHM);
                cipher.init(encryptMode, key, gcmparams);
                return cipher;
            } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
                    | InvalidAlgorithmParameterException | InvalidKeySpecException ex) {
                throw new AssertionError(ex);
            }
        }
    //Decryption Algo
        public String decrypt(String encrypted){
            byte[] decFeeder = Base64.getDecoder().decode(encrypted);
            String key = "someKey"; // A new key will be provided by APIF through a secure channel
            char[] password = key.toCharArray();
            try {
                byte[] iv = Arrays.copyOfRange(decFeeder, 0, 32);
                byte[] ciphertext = Arrays.copyOfRange(decFeeder, iv.length, decFeeder.length);
                Cipher cipher = initCipher(Cipher.DECRYPT_MODE, key, iv);
                byte[] message = cipher.doFinal(ciphertext);
                String decrypted = new String(message);
                return decrypted;
            } catch (IllegalBlockSizeException | BadPaddingException | InvalidKeySpecException ex) {
                throw new AssertionError(ex);
            }
        }
} 

我在 Swift 中使用了下面的代码来生成与上面的 JAVA 代码相同的代码，但我无法解密消息/密文。

 func aesDecrypt(encryptedData: Data, password: String) -> Data? {
       
        let iv = Array([UInt8](encryptedData)[0 ..< 33])
        let ivData = Data(iv)
        let encryptedCipher = [UInt8](encryptedData)[iv.count ..< encryptedData.count]
        let encryptedCipherData = Data(encryptedCipher)
        
        let passwordKey = createKey(password:Data(password.utf8) , salt: ivData)

        var decryptSuccess = false
        let size = (encryptedCipher.count) + kCCBlockSizeAES128
        var clearTextData = Data.init(count: size)
        
        var numberOfBytesDecrypted : size_t = 0
        let cryptStatus = ivData.withUnsafeBytes {ivBytes in
            clearTextData.withUnsafeMutableBytes {clearTextBytes in
                encryptedCipherData.withUnsafeBytes {encryptedBytes in
                    passwordKey.withUnsafeBytes {keyBytes in
                        CCCrypt(CCOperation(kCCDecrypt),
                                CCAlgorithm(kCCAlgorithmAES128),
                                CCOptions(kCCOptionPKCS7Padding),
                                keyBytes,
                                passwordKey.count,
                                ivBytes,
                                encryptedBytes,
                                (encryptedCipher.count),
                                clearTextBytes,
                                size,
                                &numberOfBytesDecrypted)
                    }
                }
            }
        }
        if cryptStatus == Int32(kCCSuccess)
        {
            clearTextData.count = numberOfBytesDecrypted
            debugPrint(clearTextData)
            decryptSuccess = true
        }
        
        
        return decryptSuccess ? clearTextData : Data.init(count: 0)
    }

    func createKey(password: Data, salt: Data) -> Data? {
           let length = kCCKeySizeAES256
           var status = Int32(0)
           var derivedBytes = [UInt8](repeating: 0, count: length)
           password.withUnsafeBytes { (passwordBytes: UnsafePointer<Int8>!) in
               salt.withUnsafeBytes { (saltBytes: UnsafePointer<UInt8>!) in
                   status = CCKeyDerivationPBKDF(CCPBKDFAlgorithm(kCCPBKDF2),  // algorithm
                                                 passwordBytes,                // password
                                                 password.count,               // passwordLen
                                                 saltBytes,                    // salt
                                                 salt.count,                   // saltLen
                                                 UInt32(kCCPRFHmacAlgSHA256),  // prf
                                                 UInt32(62233),                // rounds
                                                 &derivedBytes,                // derivedKey
                                                 length)                       // derivedKeyLen
               }
           }
           guard status == 0 else {
              return nil
           }
           return Data(bytes: UnsafePointer<UInt8>(derivedBytes), count: length)
       }

用法：

 guard let encryptedData = Data(base64Encoded: input) else{
  return nil
}
let decryptData = aesDecrypt3(encryptedData: encryptedData)
let decryptedMessage = String(data: decryptData, encoding: .utf8) ?? "Unable to Decrypt"

任何线索将不胜感激，我想知道在 swift 中尝试转换时是否缺少一些配置或数据转换。

Answer 1

我能够使用“CryptoSwift”框架解密输入，想知道我们是否可以使用苹果 iOS CommonCrypto框架来解决这个问题。

任何使用“CommonCrypto”的线索将不胜感激

 class func decryptCode123(_ cipher:String)-> String{
        
        let key = "SOMEKEY"
        
        var keyBytes: [UInt8] = []
        var codeBytes: [UInt8] = []
        var code = ""

        if let keyData = NSData(base64Encoded:key, options: .ignoreUnknownCharacters) {
            keyBytes = [UInt8](keyData as Data)
        }
        if let codeData = NSData(base64Encoded: cipher, options: .ignoreUnknownCharacters) {
            codeBytes = [UInt8](codeData as Data)
        }

        debugPrint(codeBytes)

        let codeBytescount = [UInt8](codeBytes).count

        let iv = Array([UInt8](codeBytes)[0 ..< 32])
        let cipher = Array([UInt8](codeBytes)[iv.count ..< codeBytescount])
        do{
            let gcm = GCM(iv: iv, mode: .combined)
            let derKey = createKey(password:Data(key.utf8), salt: Data(iv))!
            
            keyBytes = [UInt8](derKey)
            
            let aes = try AES(key: keyBytes, blockMode: gcm, padding: .pkcs5)
            
            print("aes created")
            let decrypted = try aes.decrypt(cipher)
            print("decrypted completed")
            if let decryptedString = String(bytes: decrypted, encoding: .utf8) {
                code = decryptedString
            }
            
            debugPrint(code)

        }catch let error as AES.Error {
            debugPrint(error.localizedDescription)
            return code
        } catch {
            return code
        }
        return code
    }