3DES加密和解密

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使用3DES加密时，遇到后端加解密数据与iOS加解密数据不一致的问题，特此记录下。

后端使用的算法algorithm参数是ecb，iOS端使用kCCOptionECBMode或者kCCOptionPKCS7Padding时，如果加密的原始数据全是数字类型时，可以得到相同的加解密结果。但是，当原始数据包含特殊字符或者字母时就跟后端得到的不一致了，正确的设置是使用(kCCOptionECBMode + kCCOptionPKCS7Padding)。

在3DES加密中，key值是24位字符串，一般我们是将原始key值经过md5加密后截取前24位作为3DES加解密的key来使用。

加解密代码：

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    func tripleDESEncryptOrDecrypt(op: CCOperation,key: String) -> String? {
        
        let iv:String? = ""
        // Key
        let keyData: NSData = (key as NSString).data(using: String.Encoding.utf8.rawValue)! as NSData
        let keyBytes = UnsafeRawPointer(keyData.bytes)
        
        // 加密或解密的内容
        var data: NSData = NSData()
        if op == CCOperation(kCCEncrypt) {
            data  = (self as NSString).data(using: String.Encoding.utf8.rawValue)! as NSData
        }
        else {
            data = NSData(base64Encoded: self, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)!
        }
        
        let dataLength = size_t(data.length)
        let dataBytes = UnsafeRawPointer(data.bytes)
        
        // 返回数据
        let cryptData = NSMutableData(length: Int(dataLength) + kCCBlockSize3DES)
        let cryptPointer = UnsafeMutableRawPointer(cryptData!.mutableBytes)
        let cryptLength = size_t(cryptData!.length)
        
        //  可选 的初始化向量
        let viData :NSData = (iv! as NSString).data(using: String.Encoding.utf8.rawValue)! as NSData
        let viDataBytes = UnsafeRawPointer(viData.bytes)
        
        // 特定的几个参数
        let keyLength = size_t(kCCKeySize3DES)
        let operation: CCOperation = UInt32(op)
        let algoritm: CCAlgorithm = UInt32(kCCAlgorithm3DES)
        let options: CCOptions = UInt32(kCCOptionECBMode + kCCOptionPKCS7Padding)
        
        var numBytesCrypted :size_t = 0
        
        let cryptStatus = CCCrypt(operation, // 加密还是解密
            algoritm, // 算法类型
            options,  // 密码块的设置选项
            keyBytes, // 秘钥的字节
            keyLength, // 秘钥的长度
            viDataBytes, // 可选初始化向量的字节
            dataBytes, // 加解密内容的字节
            dataLength, // 加解密内容的长度
            cryptPointer, // output data buffer
            cryptLength,  // output data length available
            &numBytesCrypted) // real output data length
        if UInt32(cryptStatus) == UInt32(kCCSuccess) {
            
            cryptData!.length = Int(numBytesCrypted)
            if op == CCOperation(kCCEncrypt)  {
                let base64cryptString = cryptData?.base64EncodedString(options: [])
                return base64cryptString
            }
            else {
                let base64cryptString = String.init(data: cryptData! as Data, encoding: String.Encoding(rawValue: String.Encoding.utf8.rawValue))
                return base64cryptString
            }
        }
        return nil
    }
}

测试数据：

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var key = "012438BF-4E53-458F-8A07-D7DDFC8FA1F8190808173932337_"
let keyStr = md5String(text: key)
key = String(keyStr.prefix(24))


let text = "1234qwer"
var encryptText:String?
var decrptText:String?
encryptText = text.tripleDESEncryptOrDecrypt(op: CCOperation(kCCEncrypt), key: key)
decrptText = "labWVwRfO4BSWJA2swHTOg==".tripleDESEncryptOrDecrypt(op: CCOptions(kCCDecrypt), key: key)
print("加密结果："+(encryptText ?? "加密失败"))
print("解密结果："+(decrptText ?? "解密失败"))