Decrypt a string encrypted on iOS with Python

Introduction

This cryptography includes a part of my study, so if you make a mistake and this will improve it, please leave a comment: bow:

environment

Xcode8.2.1
macOS Sierra
iOS10 (on Simulator)
Swift3
CocoaPods 1.1.1
Python3.6

encryption

This time we will use encryption using AES. No matter how much HTTPS communication is used, unless MITM measures are specified, sending and receiving of passwords etc. can be seen in plain text. Let's at least encrypt it.

Implementation is on the iOS side.

Library

CryptoSwift 0.6.7

Make a project appropriately Library installation

`python`


$ pod init

`Podfile`


pod 'CryptoSwift', '~> 0.6'

`python`


$ pod install

Sample source

`Hoge.swift`


import Foundation
import CryptoSwift  //At the time of writing here, "⌘+B "should be done

class Hoge: NSObject {
    func hoge(_ text: String) {
        let bytes = [UInt8](text.utf8)
        //Change each person according to the AES key method
        let key = [UInt8]("12345678901234567890123456789012".utf8)
        let iv: [UInt8] = AES.randomIV(AES.blockSize)

        do {
            let aes = try AES(key: key, iv: iv, blockMode: .CBC)
            let encrypted = try aes.encrypt(bytes)
            let encryptedData = Data(bytes: encrypted, count: encrypted.count)
            let sendData = NSMutableData(bytes: iv, length: iv.count)
            sendData.append(encryptedData)
            let sendDataBase64 = sendData.base64EncodedString(options: .lineLength64Characters)
            print("Encrypt: \(sendDataBase64)")
            // Encrypt: rLKCA1hNmqu2dq+08E9mK2lBlspQN0+CYBkWkCQz7IvHhh+qbfysc26Oh1SS4Adq
        } catch let error {
            print("Error: \(error)")
        }
    }
}

I think that encryption was possible for the time being. The character string used this time is "Lorem ipsum dolor sit amet". After that, Alamofire will fly to the server. I will omit it.

Decryption

Basically, I use Django when making a server side that seems to require encryption, but I do not touch the Django-specific part, so it is not bad ...

Library

Simple-AES-Cipher 1.0.0

It is recommended because you can write the encryption and decryption process very easily.

Sample source

`decrypt.py`


from simple_aes_cipher import AESCipher


encrypt = 'rLKCA1hNmqu2dq+08E9mK2lBlspQN0+CYBkWkCQz7IvHhh+qbfysc26Oh1SS4Adq'
cipher = AESCipher('12345678901234567890123456789012')
plain_text = cipher.decrypt(encrypt)

print(plain_text)  # Lorem ipsum dolor sit amet

It seems that it was successfully decrypted: clap :: clap :: clap ::