NSA Away(Increase your privacy and security by exchanging short messages securely)

管理员语：

此设计在国外一个创客大赛中找到，设计的中心思想是保证在网络交流中的安全和隐私。

由于内容介绍全部是英文，很多是专业术语，作为硬件设计出身的我也不敢轻易翻译。先将设计内容以英文形式呈现，同时征集可以完整翻译的专业人士，可以通过发起讨论来交流。

首先给大家展示这个系统的工作示意图，整个项目介绍在附件里。

Example workflow

Before needing to send a private message:

Use the dedicated hardware key generator to populate two SD cards with identical one-time pad keys

Keep one copy of the key for your self and give the other copy to the message recipient

To send a message:

Type a message on the encryption device using the software keyboard

Choose the appropriate encryption key from an SD card to encrypt the message. You would choose a key that you pre-exchanged with the message recipient.

The encryption device encrypts the message using that key

Start composing an email to the message recipient on your PC and have the cursor active in the message compose window

Plug in the encryption device via USB and click send to have the encrypted message typed into your email. Your encrypted message will be typed into your email message by the encryption device sending keystrokes.

• Send the email on the PC

To receive a message:

• Open the email containing the encrypted message on your PC
• Point the encryption device’s camera at the encrypted message and take a picture of the encrypted message

• The encryption device performs optical character recognition (OCR) and interprets the data
• Choose an appropriate key from an SD card to decrypt the message. You would choose a key that you pre-exchanged with the message sender.
• The encryption device decrypts the message using that key
• You read the message displayed on the encryption device’s screen

As long as key exchange and management is done properly and the Android device remains physically secure this solution should provide very private and secure message transmission. The portion of the key used for encrypting or decrypting the message are deleted after use, thus also providing forward secrecy: the unencrypted message cannot be recovered from either the sender or the receiver once it is sent and read.