swift4 aes128 encode

    static let fixkey = Data(bytes: [171, 221, 144, 111, 79, 19, 231, 93, 101, 8, 84, 181, 85, 164, 105, 161]) // 16bytes

    static func encrypt(_ value: String) -> Data? {
        guard let src = value.data(using: .utf8) else { return nil }
        var dst = Data(count: kCCBlockSizeAES128 + src.count)
        let dstlen = dst.count
        var numBytes: size_t = 0

        let cryptStatus = dst.withUnsafeMutableBytes { dstBytes in
            src.withUnsafeBytes { srcBytes in
                fixkey.withUnsafeBytes { keyBytes in
                    CCCrypt(
                        CCOperation(kCCEncrypt), CCAlgorithm(kCCAlgorithmAES),
                        CCOptions(kCCOptionPKCS7Padding | kCCOptionECBMode),
                        keyBytes, fixkey.count, nil,
                        srcBytes, src.count,
                        dstBytes, dstlen, &numBytes)
                }
            }
        }
        if cryptStatus != kCCSuccess { return nil }
        return dst[0 ..< numBytes]
    }

    static func decrypt(_ src: Data) -> String? {
        var dst = Data(count: kCCBlockSizeAES128 + src.count)
        let dstlen = dst.count
        var numBytes: size_t = 0

        let cryptStatus = dst.withUnsafeMutableBytes { dstBytes in
            src.withUnsafeBytes { srcBytes in
                fixkey.withUnsafeBytes { keyBytes in
                    CCCrypt(
                        CCOperation(kCCDecrypt), CCAlgorithm(kCCAlgorithmAES),
                        CCOptions(kCCOptionPKCS7Padding | kCCOptionECBMode),
                        keyBytes, fixkey.count, nil,
                        srcBytes, src.count,
                        dstBytes, dstlen, &numBytes)
                }
            }
        }

        if cryptStatus != kCCSuccess { return nil }
        return String(data: dst[0 ..< numBytes], encoding: .utf8)
    }