ios - swift 中的 AES 加密

Question

我正在尝试快速实现 AES 加密。 Android和C#的加密解密工作正常。我需要 swift 实现它。这是current code对于 android 和 C# 后面跟着这个。

我试过

1. CryptoSwift
2. Cross platform AES encryption

但都没有用。当我在服务器上发送加密字符串时，它没有被解密。

任何帮助将不胜感激

Answer 1

一定要使用相同的参数，这些参数似乎是 AES 和 CBC 模式，带有 iv、PKCS5Padding(实际上是 PKCS#7)填充和 16 字节(128 位) key 。

PKCS#5 填充和 PKCS#7 填充本质上是相同的，有时由于历史原因，PKCS#5 填充被指定用于 AES，但实际填充是 PKCS#7。

确保 key 、iv 和加密数据的编码都匹配。十六进制将它们转储到两个平台上以确保它们相同。加密函数并不难用，只要输入参数正确，输出就正确。

为了使这更安全，iv 应该是随机字节并添加到加密数据之前，以便在解密期间使用。

跨平台 AES 加密使用 256 位 key ，因此无法按原样工作。

例子:

Swift 2

// operation: kCCEncrypt or kCCDecrypt
func testCrypt(data data:[UInt8], keyData:[UInt8], ivData:[UInt8], operation:Int) -> [UInt8]? {
    let cryptLength  = size_t(data.count+kCCBlockSizeAES128)
    var cryptData    = [UInt8](count:cryptLength, repeatedValue:0)

    let keyLength             = size_t(kCCKeySizeAES128)
    let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
    let options:  CCOptions   = UInt32(kCCOptionPKCS7Padding)

    var numBytesEncrypted :size_t = 0

    let cryptStatus = CCCrypt(CCOperation(operation),
                              algoritm,
                              options,
                              keyData, keyLength,
                              ivData,
                              data, data.count,
                              &cryptData, cryptLength,
                              &numBytesEncrypted)

    if UInt32(cryptStatus) == UInt32(kCCSuccess) {
        cryptData.removeRange(numBytesEncrypted..<cryptData.count)

    } else {
        print("Error: \(cryptStatus)")
    }

    return cryptData;
}

let message       = "Don´t try to read this text. Top Secret Stuff"
let messageData   = Array(message.utf8)
let keyData       = Array("12345678901234567890123456789012".utf8)
let ivData        = Array("abcdefghijklmnop".utf8)
let encryptedData = testCrypt(data:messageData,   keyData:keyData, ivData:ivData, operation:kCCEncrypt)!
let decryptedData = testCrypt(data:encryptedData, keyData:keyData, ivData:ivData, operation:kCCDecrypt)!
var decrypted     = String(bytes:decryptedData, encoding:NSUTF8StringEncoding)!

print("message:       \(message)");
print("messageData:   \(NSData(bytes:messageData,   length:messageData.count))");
print("keyData:       \(NSData(bytes:keyData,       length:keyData.count))");
print("ivData:        \(NSData(bytes:ivData,        length:ivData.count))");
print("encryptedData: \(NSData(bytes:encryptedData, length:encryptedData.count))");
print("decryptedData: \(NSData(bytes:decryptedData, length:decryptedData.count))");
print("decrypted:     \(String(bytes:decryptedData,encoding:NSUTF8StringEncoding)!)");

输出:

message:       Don´t try to read this text. Top Secret Stuff  messageData:   446f6ec2 b4742074 72792074 6f207265 61642074 68697320 74657874 2e20546f 70205365 63726574 20537475 6666  keyData:       31323334 35363738 39303132 33343536 37383930 31323334 35363738 39303132  ivData:        61626364 65666768 696a6b6c 6d6e6f70  encryptedData: b1b6dc17 62eaf3f8 baa1cb87 21ddc35c dee803ed fb320020 85794848 21206943 a85feb5b c8ee58fc d6fb664b 96b81114  decryptedData: 446f6ec2 b4742074 72792074 6f207265 61642074 68697320 74657874 2e20546f 70205365 63726574 20537475 6666  decrypted:     Don´t try to read this text. Top Secret Stuff  

Swift 3 with [UInt8] type

func testCrypt(data:[UInt8], keyData:[UInt8], ivData:[UInt8], operation:Int) -> [UInt8]? {
    let cryptLength  = size_t(data.count+kCCBlockSizeAES128)
    var cryptData    = [UInt8](repeating:0, count:cryptLength)

    let keyLength             = size_t(kCCKeySizeAES128)
    let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
    let options:  CCOptions   = UInt32(kCCOptionPKCS7Padding)

    var numBytesEncrypted :size_t = 0

    let cryptStatus = CCCrypt(CCOperation(operation),
                              algoritm,
                              options,
                              keyData, keyLength,
                              ivData,
                              data, data.count,
                              &cryptData, cryptLength,
                              &numBytesEncrypted)

    if UInt32(cryptStatus) == UInt32(kCCSuccess) {
        cryptData.removeSubrange(numBytesEncrypted..<cryptData.count)

    } else {
        print("Error: \(cryptStatus)")
    }

    return cryptData;
}

Swift 3 & 4 with Data type

func testCrypt(data:Data, keyData:Data, ivData:Data, operation:Int) -> Data {
    let cryptLength  = size_t(data.count + kCCBlockSizeAES128)
    var cryptData = Data(count:cryptLength)

    let keyLength             = size_t(kCCKeySizeAES128)
    let options   = CCOptions(kCCOptionPKCS7Padding)


    var numBytesEncrypted :size_t = 0

    let cryptStatus = cryptData.withUnsafeMutableBytes {cryptBytes in
        data.withUnsafeBytes {dataBytes in
            ivData.withUnsafeBytes {ivBytes in
                keyData.withUnsafeBytes {keyBytes in
                    CCCrypt(CCOperation(operation),
                              CCAlgorithm(kCCAlgorithmAES),
                              options,
                              keyBytes, keyLength,
                              ivBytes,
                              dataBytes, data.count,
                              cryptBytes, cryptLength,
                              &numBytesEncrypted)
                }
            }
        }
    }

    if UInt32(cryptStatus) == UInt32(kCCSuccess) {
        cryptData.removeSubrange(numBytesEncrypted..<cryptData.count)

    } else {
        print("Error: \(cryptStatus)")
    }

    return cryptData;
}

let message     = "Don´t try to read this text. Top Secret Stuff"
let messageData = message.data(using:String.Encoding.utf8)!
let keyData     = "12345678901234567890123456789012".data(using:String.Encoding.utf8)!
let ivData      = "abcdefghijklmnop".data(using:String.Encoding.utf8)!

let encryptedData = testCrypt(data:messageData,   keyData:keyData, ivData:ivData, operation:kCCEncrypt)
let decryptedData = testCrypt(data:encryptedData, keyData:keyData, ivData:ivData, operation:kCCDecrypt)
var decrypted     = String(bytes:decryptedData, encoding:String.Encoding.utf8)!

来自已停用文档部分的示例:

CBC 模式下使用随机 IV 的 AES 加密 (Swift 3+)

iv是加密数据的前缀

aesCBC128Encrypt 将创建一个随机 IV 并作为加密代码的前缀。
aesCBC128Decrypt 将在解密期间使用带前缀的 IV。

输入是数据，键是数据对象。如果需要在调用方法中转换为和/或自 Base64 等编码形式。

key 的长度应恰好为 128 位(16 字节)、192 位(24 字节)或 256 位(32 字节)。如果使用其他 key 大小，则会抛出错误。

PKCS#7 padding 是默认设置的。

这个例子需要通用加密
必须要有项目的桥接头:
#import <CommonCrypto/CommonCrypto.h>
将 Security.framework 添加到项目中。

这是示例，不是生产代码。

enum AESError: Error {
    case KeyError((String, Int))
    case IVError((String, Int))
    case CryptorError((String, Int))
}

// The iv is prefixed to the encrypted data
func aesCBCEncrypt(data:Data, keyData:Data) throws -> Data {
    let keyLength = keyData.count
    let validKeyLengths = [kCCKeySizeAES128, kCCKeySizeAES192, kCCKeySizeAES256]
    if (validKeyLengths.contains(keyLength) == false) {
        throw AESError.KeyError(("Invalid key length", keyLength))
    }

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

    let status = cryptData.withUnsafeMutableBytes {ivBytes in
        SecRandomCopyBytes(kSecRandomDefault, kCCBlockSizeAES128, ivBytes)
    }
    if (status != 0) {
        throw AESError.IVError(("IV generation failed", Int(status)))
    }

    var numBytesEncrypted :size_t = 0
    let options   = CCOptions(kCCOptionPKCS7Padding)

    let cryptStatus = cryptData.withUnsafeMutableBytes {cryptBytes in
        data.withUnsafeBytes {dataBytes in
            keyData.withUnsafeBytes {keyBytes in
                CCCrypt(CCOperation(kCCEncrypt),
                        CCAlgorithm(kCCAlgorithmAES),
                        options,
                        keyBytes, keyLength,
                        cryptBytes,
                        dataBytes, data.count,
                        cryptBytes+kCCBlockSizeAES128, cryptLength,
                        &numBytesEncrypted)
            }
        }
    }

    if UInt32(cryptStatus) == UInt32(kCCSuccess) {
        cryptData.count = numBytesEncrypted + ivSize
    }
    else {
        throw AESError.CryptorError(("Encryption failed", Int(cryptStatus)))
    }

    return cryptData;
}

// The iv is prefixed to the encrypted data
func aesCBCDecrypt(data:Data, keyData:Data) throws -> Data? {
    let keyLength = keyData.count
    let validKeyLengths = [kCCKeySizeAES128, kCCKeySizeAES192, kCCKeySizeAES256]
    if (validKeyLengths.contains(keyLength) == false) {
        throw AESError.KeyError(("Invalid key length", keyLength))
    }

    let ivSize = kCCBlockSizeAES128;
    let clearLength = size_t(data.count - ivSize)
    var clearData = Data(count:clearLength)

    var numBytesDecrypted :size_t = 0
    let options   = CCOptions(kCCOptionPKCS7Padding)

    let cryptStatus = clearData.withUnsafeMutableBytes {cryptBytes in
        data.withUnsafeBytes {dataBytes in
            keyData.withUnsafeBytes {keyBytes in
                CCCrypt(CCOperation(kCCDecrypt),
                        CCAlgorithm(kCCAlgorithmAES128),
                        options,
                        keyBytes, keyLength,
                        dataBytes,
                        dataBytes+kCCBlockSizeAES128, clearLength,
                        cryptBytes, clearLength,
                        &numBytesDecrypted)
            }
        }
    }

    if UInt32(cryptStatus) == UInt32(kCCSuccess) {
        clearData.count = numBytesDecrypted
    }
    else {
        throw AESError.CryptorError(("Decryption failed", Int(cryptStatus)))
    }

    return clearData;
}

示例用法:

let clearData = "clearData0123456".data(using:String.Encoding.utf8)!
let keyData   = "keyData890123456".data(using:String.Encoding.utf8)!
print("clearData:   \(clearData as NSData)")
print("keyData:     \(keyData as NSData)")

var cryptData :Data?
do {
    cryptData = try aesCBCEncrypt(data:clearData, keyData:keyData)
    print("cryptData:   \(cryptData! as NSData)")
}
catch (let status) {
    print("Error aesCBCEncrypt: \(status)")
}

let decryptData :Data?
do {
    let decryptData = try aesCBCDecrypt(data:cryptData!, keyData:keyData)
    print("decryptData: \(decryptData! as NSData)")
}
catch (let status) {
    print("Error aesCBCDecrypt: \(status)")
}

示例输出:

clearData:   <636c6561 72446174 61303132 33343536>
keyData:     <6b657944 61746138 39303132 33343536>
cryptData:   <92c57393 f454d959 5a4d158f 6e1cd3e7 77986ee9 b2970f49 2bafcf1a 8ee9d51a bde49c31 d7780256 71837a61 60fa4be0>
decryptData: <636c6561 72446174 61303132 33343536>

注意事项:
CBC 模式示例代码的一个典型问题是它将随机 IV 的创建和共享留给了用户。此示例包括 IV 的生成、为加密数据添加前缀并在解密期间使用带前缀的 IV。这将临时用户从 CBC mode 所需的详细信息中解放出来。

为了安全起见，加密的数据也应该有身份验证，这个示例代码没有提供，为了体积小并允许与其他平台更好的互操作性。

还缺少从密码中导出 key 的 key ，建议使用 PBKDF2 将文本密码用作 key Material 。

对于健壮的生产就绪的多平台加密代码，请参阅 RNCryptor。